The following information about waterfowl biology, ecology, physiology and behavior was obtained from:
(1) WATERFOWL ECOLOGY by Michael Owen and Jeff Black; and
(2) WILD GOOSE DILEMMAS by Jeff Black, Jouke Prop, and Kjell Larsson
Introduction
What is waterfowl?
The term "waterfowl" refers to birds that at some point of their lives depend on wetlands. Waterfowl are divided in three main families: (1) Anhimidae, (2) Anseranatidae, and (3) Anatidae. The family Anhimidae is distributed in the South American rainforest in Venezuela, Colombia, Ecuador, Brazil and Peru. Horned Screamers are birds that belong to this family. They have semi-webbed feet, but their main characteristic is the horned in their heads and sharpie spurs in their wings that used for self-defense. The family Anseranatidae is best represented by the Magpie goose which is the only living species of this family. This bird is found in Australia and New Guinea. Additionally, most of the waterfowl known by men belongs to the family Anatidae. This family has been subdivided in tribes that usually tell something in particular about the groups: dendrocygnini (whistling ducks), anserini (geese), cygnini (swans), merganettini (torrent ducks), tadornini (shelducks & sheldgeese), anatini (dabbling ducks), aythyini (diving ducks), mergini (sea ducks), and oxyurini (stiff-tailed ducks).
The term "waterfowl" refers to birds that at some point of their lives depend on wetlands. Waterfowl are divided in three main families: (1) Anhimidae, (2) Anseranatidae, and (3) Anatidae. The family Anhimidae is distributed in the South American rainforest in Venezuela, Colombia, Ecuador, Brazil and Peru. Horned Screamers are birds that belong to this family. They have semi-webbed feet, but their main characteristic is the horned in their heads and sharpie spurs in their wings that used for self-defense. The family Anseranatidae is best represented by the Magpie goose which is the only living species of this family. This bird is found in Australia and New Guinea. Additionally, most of the waterfowl known by men belongs to the family Anatidae. This family has been subdivided in tribes that usually tell something in particular about the groups: dendrocygnini (whistling ducks), anserini (geese), cygnini (swans), merganettini (torrent ducks), tadornini (shelducks & sheldgeese), anatini (dabbling ducks), aythyini (diving ducks), mergini (sea ducks), and oxyurini (stiff-tailed ducks).
Waterfowl and Man
The relationship between and waterfowl and men was initiated by the Native Americans and European centuries ago. Native had a different perspective about wildlife and nature in general; however, the overexploitation in the Americas began when the Europeans arrived to the new world. Back in the 1600s, people had an Anthropocentric view towards nature and all decisions were based on the benefits that humans will obtain from it. For this reason, many waterfowl species went extinct and some others were considered endangered for several years. Nowadays, waterfowl regulations and hunting seasons are monitored; however, the purpose of the conservation of waterfowl remains an anthropocentric idea because it mainly for the purpose of hunting rather than the intrinsic value of the individuals.
The relationship between and waterfowl and men was initiated by the Native Americans and European centuries ago. Native had a different perspective about wildlife and nature in general; however, the overexploitation in the Americas began when the Europeans arrived to the new world. Back in the 1600s, people had an Anthropocentric view towards nature and all decisions were based on the benefits that humans will obtain from it. For this reason, many waterfowl species went extinct and some others were considered endangered for several years. Nowadays, waterfowl regulations and hunting seasons are monitored; however, the purpose of the conservation of waterfowl remains an anthropocentric idea because it mainly for the purpose of hunting rather than the intrinsic value of the individuals.
Waterfowl and Wetlands
Waterfowl have a very close link to wetlands therefore the conservation of waterfowl is closely related to the conservations of wetlands and suitable habitats that swan, geese and ducks. Men are directly related to climate change and the warmer/colder temperature affects their behavior such as migration timing, direction, breeding areas, suitable areas, and other components that directly affect their population growth and population dynamics.
Waterfowl have a very close link to wetlands therefore the conservation of waterfowl is closely related to the conservations of wetlands and suitable habitats that swan, geese and ducks. Men are directly related to climate change and the warmer/colder temperature affects their behavior such as migration timing, direction, breeding areas, suitable areas, and other components that directly affect their population growth and population dynamics.
Food and Feeding
Adaptive Radiation
Evolution is evident in waterfowl because species share some common characteristics but they also differ in some others too.These similarities and differences are observed in all species such is the case of geese in North America and Europe. The barnacle goose has short bill for quick pecking when they feed on grasslands whereas the Brent is found on saltmarshes and feed on eelgrass. Another example of speciation is the Hawaiian goose (Nene) who spends most of their time in land and rarely gets their feet in the water.
Terrestrial vegetation:
-short serrated bill for cutting grass blades (Ross' Goose, wigeon).
-large gizzard for grinding up course vegetation.
-long cacae to facilitate hind-gut fermentation of cell-wall fractions.
-rapid ingesta throughput to facilitate high energy gain from low energy foodstuffs.
-spend more time feeding.
Aquatic vegetation:
-wider, spatulate bill (swans, Redheads)
-large gizzard for grinding.
-long intestines and cacae for digestion of large volumes of low energy food.
-long necks (swans) or diving ability (Redheads, coots).
-spend more time feeding (e.g. wintering Gadwalls feed 64% of the time; Mallards on waste grain feed 34%).
Tubers and rhizomes:
-robust bill, head, and neck for digging (swans, Snow Geese, Canvasbacks).
-long neck or diving ability (swans and Canvasbacks; aquatic tubers)
-small gizzard and GI tract (high carbohydrate, soft, easy to digest).
Seeds:
-dabbling type feeding method for windrowed seeds in shallow water
-lamellae allow water and seeds to be taken in, seeds retained, water expelled
-agile bills for picking up waste grain from fields.
-relatively large gizzard to grind up seed husk (up to acorn in size)
Aquatic invertebrates:
-lamellae for straining inverts from water.
-dabbling ability (long necks) or diving ability (Ruddy Duck, Lesser Scaup).
-minimal gizzard and GI tract needed (easy to digest)
Mollusks:
-stout bill for ripping sessile mollusks from attached rocks (Eiders, Scoters)
-strong, deep divers (Mergini use wings to dive, like Alcidae).
Oldsquaws are deepest divers; gillnet captures at depths down to 240 feet!
-big gizzard for breaking shells, small GI tract for easily digestible food. Fish:
-serrated bill for grabbing fish.
-strong, fast, agile divers.
-easy to digest, small gizzard and GI tract.
Note that bill and locomotory morphology are fixed; limiting a species dietary options.
Notes from Todd Arnold
Evolution is evident in waterfowl because species share some common characteristics but they also differ in some others too.These similarities and differences are observed in all species such is the case of geese in North America and Europe. The barnacle goose has short bill for quick pecking when they feed on grasslands whereas the Brent is found on saltmarshes and feed on eelgrass. Another example of speciation is the Hawaiian goose (Nene) who spends most of their time in land and rarely gets their feet in the water.
Terrestrial vegetation:
-short serrated bill for cutting grass blades (Ross' Goose, wigeon).
-large gizzard for grinding up course vegetation.
-long cacae to facilitate hind-gut fermentation of cell-wall fractions.
-rapid ingesta throughput to facilitate high energy gain from low energy foodstuffs.
-spend more time feeding.
Aquatic vegetation:
-wider, spatulate bill (swans, Redheads)
-large gizzard for grinding.
-long intestines and cacae for digestion of large volumes of low energy food.
-long necks (swans) or diving ability (Redheads, coots).
-spend more time feeding (e.g. wintering Gadwalls feed 64% of the time; Mallards on waste grain feed 34%).
Tubers and rhizomes:
-robust bill, head, and neck for digging (swans, Snow Geese, Canvasbacks).
-long neck or diving ability (swans and Canvasbacks; aquatic tubers)
-small gizzard and GI tract (high carbohydrate, soft, easy to digest).
Seeds:
-dabbling type feeding method for windrowed seeds in shallow water
-lamellae allow water and seeds to be taken in, seeds retained, water expelled
-agile bills for picking up waste grain from fields.
-relatively large gizzard to grind up seed husk (up to acorn in size)
Aquatic invertebrates:
-lamellae for straining inverts from water.
-dabbling ability (long necks) or diving ability (Ruddy Duck, Lesser Scaup).
-minimal gizzard and GI tract needed (easy to digest)
Mollusks:
-stout bill for ripping sessile mollusks from attached rocks (Eiders, Scoters)
-strong, deep divers (Mergini use wings to dive, like Alcidae).
Oldsquaws are deepest divers; gillnet captures at depths down to 240 feet!
-big gizzard for breaking shells, small GI tract for easily digestible food. Fish:
-serrated bill for grabbing fish.
-strong, fast, agile divers.
-easy to digest, small gizzard and GI tract.
Note that bill and locomotory morphology are fixed; limiting a species dietary options.
Notes from Todd Arnold
Exploitation of habitats
Waterfowl species take advantages of their unique characteristics to exploit their habitats effectively. Swans have a very long neck that allow them to reach over one meter under water, whereas geese and sheldgeese spend most of their time on land but always near water to protect themselves from predators. Some geese like the white-fronted goose feed 95% of the time during daylight. Most dabbling ducks and diving ducls feed at night and are difficult to observe with some exception like the Bufflehead who also feed during the day (Personal observation).
Waterfowl species take advantages of their unique characteristics to exploit their habitats effectively. Swans have a very long neck that allow them to reach over one meter under water, whereas geese and sheldgeese spend most of their time on land but always near water to protect themselves from predators. Some geese like the white-fronted goose feed 95% of the time during daylight. Most dabbling ducks and diving ducls feed at night and are difficult to observe with some exception like the Bufflehead who also feed during the day (Personal observation).
Interesting Facts:
"...barnacle geese forage for seven hours of an 8-hour winter day, and in spring, when daylight allows they may forage for 17 hours or more."
"Film records made by high-speed cameras show how exactly geese are harvesting vegetation. Each peak (taking less than 0.5 second) is composed of rapid movements by head, bill, and tongue..."
"...barnacle geese forage for seven hours of an 8-hour winter day, and in spring, when daylight allows they may forage for 17 hours or more."
"Film records made by high-speed cameras show how exactly geese are harvesting vegetation. Each peak (taking less than 0.5 second) is composed of rapid movements by head, bill, and tongue..."
Food selection and energy cycle
As in any other group, food selection does not occur randomly in waterfowl. They intensity in which they feed in also determine by the time of the year because breeding season plays a critical role in the feeding behavior of waterfowl. The following is an example of how some species gain and lose weigh in a short period f time:
-Female 110-200 lbs in 2 months then drop back to 100 lbs in a month
-Male 130 to 190 lbs to 150 lbs
-Juveniles 10 to 150 lbs in 2.5 months
Geese evolved vegetarian but their digestive system is poor at absorbing nutrients therefore they need to eat a lot to be in good shape. Waterfowl species can be endogenous or exogenous. The first one means that some species lay their eggs based on the fat (energy) stored in their bodies, the fatter, the better. Exogenous means females lay their eggs based on the food (energy) available in the area at that particular time.
As in any other group, food selection does not occur randomly in waterfowl. They intensity in which they feed in also determine by the time of the year because breeding season plays a critical role in the feeding behavior of waterfowl. The following is an example of how some species gain and lose weigh in a short period f time:
-Female 110-200 lbs in 2 months then drop back to 100 lbs in a month
-Male 130 to 190 lbs to 150 lbs
-Juveniles 10 to 150 lbs in 2.5 months
Geese evolved vegetarian but their digestive system is poor at absorbing nutrients therefore they need to eat a lot to be in good shape. Waterfowl species can be endogenous or exogenous. The first one means that some species lay their eggs based on the fat (energy) stored in their bodies, the fatter, the better. Exogenous means females lay their eggs based on the food (energy) available in the area at that particular time.
Ladin ZS, Castelli P, McWilliams S and Williams C. 2011. Time Energy Budget and Food Use of Atlantic Brant Across Their Wintering Range. The Wildlife Society 75(2):273–282.
This paper talks about the daily energy expenditure and food use of the Atlantic Brant. This study took place between Rhode Island and Virginia where 1441 independent behavioral scans were completed by measuring the average basal metabolic rate, behavioral activity, cost of thermoregulation and time engaged in behavioral activity. Results indicated that daily energy expenditure was the highest in January and lowest in May with numbers of 2018±173 kJ/day and 1049±137 kJ/day respectively. Flying activity was also the greater in January and lower in May. In addition, the results indicated that body condition index of birds were low from January, February, and March compared to November, December and April. With respect to food, different types of food were found on carcasses being macroalgae the most abundant with 40-60% followed by eelgrass with 45%.
This paper talks about the daily energy expenditure and food use of the Atlantic Brant. This study took place between Rhode Island and Virginia where 1441 independent behavioral scans were completed by measuring the average basal metabolic rate, behavioral activity, cost of thermoregulation and time engaged in behavioral activity. Results indicated that daily energy expenditure was the highest in January and lowest in May with numbers of 2018±173 kJ/day and 1049±137 kJ/day respectively. Flying activity was also the greater in January and lower in May. In addition, the results indicated that body condition index of birds were low from January, February, and March compared to November, December and April. With respect to food, different types of food were found on carcasses being macroalgae the most abundant with 40-60% followed by eelgrass with 45%.
Breeding Biology
Timing pair formation
Mating in waterfowl is different from other birds because they start pairing during the winter, months before breeding season. There are several reasons why waterfowl choose their mates months before the breeding season. First, females need to store energy by gaining weight for the egg laying and incubation period. In order for females to feed constantly, males need to be vigilant if a predator is approaching. Also early mating is beneficial because they can explore together the area for the best place to build their nest and the pair supports each other if intraspecific competition takes place.
Mating in waterfowl is different from other birds because they start pairing during the winter, months before breeding season. There are several reasons why waterfowl choose their mates months before the breeding season. First, females need to store energy by gaining weight for the egg laying and incubation period. In order for females to feed constantly, males need to be vigilant if a predator is approaching. Also early mating is beneficial because they can explore together the area for the best place to build their nest and the pair supports each other if intraspecific competition takes place.
Interesting Facts:
"58% of the females from the 1876-cohort eventually chose mates from the same natal origin even though they only had a 1 in 5 chance of doing so, assuming that most birds from different colonies mix together in the wintering colonies."
"Once the pair bond is established the Triumph Ceremony is still practiced by pair members throughout the year, with a peak in frequency occurring in the spring."
"58% of the females from the 1876-cohort eventually chose mates from the same natal origin even though they only had a 1 in 5 chance of doing so, assuming that most birds from different colonies mix together in the wintering colonies."
"Once the pair bond is established the Triumph Ceremony is still practiced by pair members throughout the year, with a peak in frequency occurring in the spring."
The timing of nesting and nest sites
The time when females start laying and incubation their eggs is not a random event. For example, ducks in northern Swedish lake synchronize the hatching event of their eggs with the time in which local bugs density are very high and more abundant. Additionally, geese nesting period varies with latitude and distance from the equator. In the tropics, there is little variation in the daylength, precipitation and weather in general; therefore, suitable habitat is available all year around. The nest site of ducks, swans and geese are related to their needs for nesting and foods (e.g. Mandarin and wood duck). It is not that all the individuals of a species migrate south/north to nest but they migrate where they know that food and nesting conditions are fulfilled.
Once they migrate to a place, then individuals have to look for the best available site to lay their egg and this depends on how safe their eggs are going to be from predators. Nests location varies in waterfowl and this variation can be in cliffs for brant and smaller species, nearby ponds for mallards and most ducks and forests for wood ducks and buffleheads. Egg, clutch size and incubation The clutch size (number of eggs laid by females) is usually correlated with the size of the species and because the bigger the egg and the more energy will be invested per egg usually results in the smaller the clutch size. It is important to remember that waterfowl chicks, compared to passerines, are precocials which means that they hatch from egg sufficiently developed to leave the nest almost immediately and get food on their own.
The following table shows the egg weight, clutch size, and clutch weight in relation to the body weight of the female.
The time when females start laying and incubation their eggs is not a random event. For example, ducks in northern Swedish lake synchronize the hatching event of their eggs with the time in which local bugs density are very high and more abundant. Additionally, geese nesting period varies with latitude and distance from the equator. In the tropics, there is little variation in the daylength, precipitation and weather in general; therefore, suitable habitat is available all year around. The nest site of ducks, swans and geese are related to their needs for nesting and foods (e.g. Mandarin and wood duck). It is not that all the individuals of a species migrate south/north to nest but they migrate where they know that food and nesting conditions are fulfilled.
Once they migrate to a place, then individuals have to look for the best available site to lay their egg and this depends on how safe their eggs are going to be from predators. Nests location varies in waterfowl and this variation can be in cliffs for brant and smaller species, nearby ponds for mallards and most ducks and forests for wood ducks and buffleheads. Egg, clutch size and incubation The clutch size (number of eggs laid by females) is usually correlated with the size of the species and because the bigger the egg and the more energy will be invested per egg usually results in the smaller the clutch size. It is important to remember that waterfowl chicks, compared to passerines, are precocials which means that they hatch from egg sufficiently developed to leave the nest almost immediately and get food on their own.
The following table shows the egg weight, clutch size, and clutch weight in relation to the body weight of the female.
Interesting Facts:
"It does not come as a surprise, therefore, that the proportion of pairs bringing one or more goslings to the wintering area in Scotland was only 0.17 (SE 0.02, n = 22 years)."
"Barnacle geese are physically capable of reproduction at the age of two years, though fewer than half of the birds bred at that young age."
"It does not come as a surprise, therefore, that the proportion of pairs bringing one or more goslings to the wintering area in Scotland was only 0.17 (SE 0.02, n = 22 years)."
"Barnacle geese are physically capable of reproduction at the age of two years, though fewer than half of the birds bred at that young age."
In addition, clutch size depends on several factors such as the experience of the female, food availability, population size, energy reserves and the time when the first egg was laid (proximity to the end of the breeding season). Besides, incubation periods last for up to a month in most species with most eggs hatching in the third and fourth week. This process has evolved and is different in swans, geese and ducks. In swans, the process of incubation involves both male and females, in geese this process involves mostly males, whereas in most duck incubation is a unique duty for females. Some species pluck down feathers leaving expose what is called “the brood patch” and some species like the Emperor goose do not pluck their down feather and their nests are composed of 99% of vegetation. The time that the female spends incubating her eggs (non-stopping) varies from 20 hours a day in the blue-winged teal to 48 consecutive hours in the Emperor goose.
Renesting
The process of renesting under the loss of their nest depends on the proximity to the end of the breeding season and the study provided by Arnold, Devries and Howeter shows the renesting process on Mallards. The study and data collection took place in 27 study sites throughout the Canadian Prairie Parklands. Approximately 135 female Mallards were radiomarked at each study site. Investigators took several bearings of nesting females and returned to the nesting location later that day when the female was absent and came back to determine clutch size when the nest failed (abandoned or destroyed) or until 18 days of incubation. Renesting propensity was the proportion of failed nests followed by a renesting attempt, whereas renesting interval is the number of days between nest destruction and laying the next nest. Nests were revised when females were absent to observe their fate. Renesting was considered when a female laid more eggs after her previous nest was destroyed or abandoned.
The process of renesting under the loss of their nest depends on the proximity to the end of the breeding season and the study provided by Arnold, Devries and Howeter shows the renesting process on Mallards. The study and data collection took place in 27 study sites throughout the Canadian Prairie Parklands. Approximately 135 female Mallards were radiomarked at each study site. Investigators took several bearings of nesting females and returned to the nesting location later that day when the female was absent and came back to determine clutch size when the nest failed (abandoned or destroyed) or until 18 days of incubation. Renesting propensity was the proportion of failed nests followed by a renesting attempt, whereas renesting interval is the number of days between nest destruction and laying the next nest. Nests were revised when females were absent to observe their fate. Renesting was considered when a female laid more eggs after her previous nest was destroyed or abandoned.
Arnold TW, Devries J and Howerter D. 2010. Factors that affect renesting in Mallards. The Auk 127(1):212-221.
The study and data collection took place in 27 study sites throughout the Canadian Prairie Parklands. Approximately 135 female Mallards were radiomarked at each study site. Investigators took several bearings of nesting females and returned to the nesting location later that day when the female was absent and came back to determine clutch size when the nest failed (abandoned or destroyed) or until 18 days of incubation. Renesting propensity was the proportion of failed nests followed by a renesting attempt, whereas renesting interval is the number of days between nest destruction and laying the next nest. Nests were revised when females were absent to observe their fate. Renesting was considered when a female laid more eggs after her previous nest was destroyed or abandoned. The paper showed that 44% of Mallards that lost their eggs during the laying process, re-nested within four days. On the other hand, only 2% of Mallards re-nested within four days when the loss of their eggs occurred after clutch completion. The renesting chance was high in the beginning of the breeding season in April and very low at the end of the breeding season in June. Most clutch sizes were 9 eggs for first and second attempts and 8 eggs for third and following attempts.
The study and data collection took place in 27 study sites throughout the Canadian Prairie Parklands. Approximately 135 female Mallards were radiomarked at each study site. Investigators took several bearings of nesting females and returned to the nesting location later that day when the female was absent and came back to determine clutch size when the nest failed (abandoned or destroyed) or until 18 days of incubation. Renesting propensity was the proportion of failed nests followed by a renesting attempt, whereas renesting interval is the number of days between nest destruction and laying the next nest. Nests were revised when females were absent to observe their fate. Renesting was considered when a female laid more eggs after her previous nest was destroyed or abandoned. The paper showed that 44% of Mallards that lost their eggs during the laying process, re-nested within four days. On the other hand, only 2% of Mallards re-nested within four days when the loss of their eggs occurred after clutch completion. The renesting chance was high in the beginning of the breeding season in April and very low at the end of the breeding season in June. Most clutch sizes were 9 eggs for first and second attempts and 8 eggs for third and following attempts.
Hatching, growth and development
Hatching is a synchronized event in which communication of the chicks (while still in the egg) is important so that they can all hatch almost at the same time. This is critical for the survival of the young because if a chick hatches too late he/she will be left behind. Ducklings leave the nest the same day after hatching by following their mother to the nearest wetland where they are safer from predation. Parents play an important role in the development of the young and some parents carry their chicks on their backs to protect them from predators whereas other species mix their chick forming big families. Ducklings take 2 months until they can fly and cygnets a little longer for up to 5 months.
Hatching is a synchronized event in which communication of the chicks (while still in the egg) is important so that they can all hatch almost at the same time. This is critical for the survival of the young because if a chick hatches too late he/she will be left behind. Ducklings leave the nest the same day after hatching by following their mother to the nearest wetland where they are safer from predation. Parents play an important role in the development of the young and some parents carry their chicks on their backs to protect them from predators whereas other species mix their chick forming big families. Ducklings take 2 months until they can fly and cygnets a little longer for up to 5 months.
Interesting Facts:
"...oldest birds became dominant over later hatched siblings even if the oldest was the smallest bird in the brood."
"When goslings grow to full size, parents may have to settle for second-best food... At this point parents must decide which goslings to exclude from the family and which to allow to remain."
"...oldest birds became dominant over later hatched siblings even if the oldest was the smallest bird in the brood."
"When goslings grow to full size, parents may have to settle for second-best food... At this point parents must decide which goslings to exclude from the family and which to allow to remain."
Age and reproductive success
The age in which some species start breeding is important for the success of the brood. For example, Mute swans show a positive correlation between age of the male and the number of young fledged. The fact that older individuals (with more experienced) have a higher reproductive success lead to the protection preference of population to be biased towards older members since they population growth depends mainly on them. This is not only the case of waterfowl but it also occurs on other birds like the Snowy Plover which is a endangered species in the coast of California that is struggling for survival and all hopes are placed on the older males (M. Colwell personal communication).
Flightless moult
Waterfowl species go under a period of moult in which all birds lose their primary and secondary feathers, also known as flight feathers, becoming flightless for a couple of weeks. This moulting process is synchronized with the hatching of their chicks so that the whole family is able to fly after a month in most ducks or two months in swans. In some cases this process is synchronized with the other parent like in Mute swans where at least one parent can always fly and protect the cygnets. This process is stressful for the birds, they lose weight because they are very vulnerable to predators and therefore they go under the process of moulting always nearby wetlands where they can run into if they feel that in danger
The age in which some species start breeding is important for the success of the brood. For example, Mute swans show a positive correlation between age of the male and the number of young fledged. The fact that older individuals (with more experienced) have a higher reproductive success lead to the protection preference of population to be biased towards older members since they population growth depends mainly on them. This is not only the case of waterfowl but it also occurs on other birds like the Snowy Plover which is a endangered species in the coast of California that is struggling for survival and all hopes are placed on the older males (M. Colwell personal communication).
Flightless moult
Waterfowl species go under a period of moult in which all birds lose their primary and secondary feathers, also known as flight feathers, becoming flightless for a couple of weeks. This moulting process is synchronized with the hatching of their chicks so that the whole family is able to fly after a month in most ducks or two months in swans. In some cases this process is synchronized with the other parent like in Mute swans where at least one parent can always fly and protect the cygnets. This process is stressful for the birds, they lose weight because they are very vulnerable to predators and therefore they go under the process of moulting always nearby wetlands where they can run into if they feel that in danger
Social and Sexual Behavior
Mating systems
Waterfowl does not follow a unique and standard mating system; however, most species practice monogamy. Most waterfowl are monogamous but this system varies considerably if we compare ducks and swans. Northern swans and geese form strong bonds that can last for many years and where the partners are together 24 hours a day the entire year. On the other side, ducks are seasonally monogamous because their bonding only last for the breeding season and some males even leave as soon as the female lay their eggs. Copulation usually occurs before they arrive to the breeding grounds and males protect their partners so that females can store the right amount of energy for the incubation period. In long-term monogamous species, males perform some others duties not observed in ducks. Geese and swan males raise their young and provide protection during their early lives. In Bewick’s Swans, the mean number of cygnets raised in a year was significantly correlated with pair-bond duration. On the other side, only three species from the tropics are known to be polygamous, the Magpie Goose, the African Comb Duck and the Maccoa Duck.
Waterfowl does not follow a unique and standard mating system; however, most species practice monogamy. Most waterfowl are monogamous but this system varies considerably if we compare ducks and swans. Northern swans and geese form strong bonds that can last for many years and where the partners are together 24 hours a day the entire year. On the other side, ducks are seasonally monogamous because their bonding only last for the breeding season and some males even leave as soon as the female lay their eggs. Copulation usually occurs before they arrive to the breeding grounds and males protect their partners so that females can store the right amount of energy for the incubation period. In long-term monogamous species, males perform some others duties not observed in ducks. Geese and swan males raise their young and provide protection during their early lives. In Bewick’s Swans, the mean number of cygnets raised in a year was significantly correlated with pair-bond duration. On the other side, only three species from the tropics are known to be polygamous, the Magpie Goose, the African Comb Duck and the Maccoa Duck.
Interesting Facts::
"Fighting can expensive in terms of energy and risk of injury, but the payoff of acquiring better food or mates may be worth the effort."
"About half the birds (51%) settled with the first mate they sampled, whilst the other half went through 1-6 potential partners or trial liaisons before settling with a consistent mate."
"Fighting can expensive in terms of energy and risk of injury, but the payoff of acquiring better food or mates may be worth the effort."
"About half the birds (51%) settled with the first mate they sampled, whilst the other half went through 1-6 potential partners or trial liaisons before settling with a consistent mate."
Other strategies
Parasitism is somewhat common in waterfowl. For example, female Wood Ducks and Lesser Snow Geese dump their eggs on other females’ nests due to the lack of experience and fail to obtain a territory. Nevertheless, the South American Black-headed duck is the only true parasite and it is well adapted to this strategy because the just-born chick is observed to leave the nest right after hatching. Additionally, some species like the Australian Magpie Geese cooperate in the incubation process by sharing the same nest and taking turns during the incubation period.
Parasitism is somewhat common in waterfowl. For example, female Wood Ducks and Lesser Snow Geese dump their eggs on other females’ nests due to the lack of experience and fail to obtain a territory. Nevertheless, the South American Black-headed duck is the only true parasite and it is well adapted to this strategy because the just-born chick is observed to leave the nest right after hatching. Additionally, some species like the Australian Magpie Geese cooperate in the incubation process by sharing the same nest and taking turns during the incubation period.
Family and flock behavior
According to Black and Owen, Barnacle geese have shown that dense flocks was the most important predictor of success. Family and flock behavior has been studied extensively especially in geese and swans. There was a study focused focused on the social support of primary families (parents raised concurrent young) and secondary families (parents did not raise concurrent young) of greylag goose by observing agonistics encounters and the extraction of corticosterone (CORT) in feces. Data collection took place in River Alm, Upper Austria, Austria. 45 individuals from a 150 non-migratory greylag goose flock were used in the study: 10 adult males, 10 adult females, and 25 subadults which were surviving offspring from the primary family units of the previous year. Behavioral protocols and fecal samples were collected during Aug’04-Feb’05 and Aug’05-Feb’06. The family was observed for 1 hour and all agonistic interactions were recorded whereas feces were collected from all the individuals within the family for 3 hours. Results indicated that primary family groups (PF) were more common than secondary families (SF). Active social support was 38% of 4474 interactions in PF and 1.5% of 965 interactions in SF. Additionally, subadult males were more likely to win agonistic encounters than subadult females. Adult females in SF excreted less CORT than females whose young had not rejoined. Subadult females excreted less CORT during social density stress when rejoining their parents; yet this passive social support was neither detectable in adult nor in subadult males. This paper is important to understand the importance of primary and secondary families; and how social support helps inexperience young adults to establish themselves in the area (Scheiber et al. 2009).
According to Black and Owen, Barnacle geese have shown that dense flocks was the most important predictor of success. Family and flock behavior has been studied extensively especially in geese and swans. There was a study focused focused on the social support of primary families (parents raised concurrent young) and secondary families (parents did not raise concurrent young) of greylag goose by observing agonistics encounters and the extraction of corticosterone (CORT) in feces. Data collection took place in River Alm, Upper Austria, Austria. 45 individuals from a 150 non-migratory greylag goose flock were used in the study: 10 adult males, 10 adult females, and 25 subadults which were surviving offspring from the primary family units of the previous year. Behavioral protocols and fecal samples were collected during Aug’04-Feb’05 and Aug’05-Feb’06. The family was observed for 1 hour and all agonistic interactions were recorded whereas feces were collected from all the individuals within the family for 3 hours. Results indicated that primary family groups (PF) were more common than secondary families (SF). Active social support was 38% of 4474 interactions in PF and 1.5% of 965 interactions in SF. Additionally, subadult males were more likely to win agonistic encounters than subadult females. Adult females in SF excreted less CORT than females whose young had not rejoined. Subadult females excreted less CORT during social density stress when rejoining their parents; yet this passive social support was neither detectable in adult nor in subadult males. This paper is important to understand the importance of primary and secondary families; and how social support helps inexperience young adults to establish themselves in the area (Scheiber et al. 2009).
Scheiber IB, Kotrschal K and Weib B. Social support in secondary graylag goose families. Hormones and Behavior 55:133-138.
This study was focused on the social support of primary families (parents raised concurrent young) and secondary families (parents did not raise concurrent young) of greylag goose by observing agonistics encounters and the extraction of corticosterone (CORT) in feces.
Data collection took place in River Alm, Upper Austria, Austria. 45 individuals from a 150 non-migratory greylag goose flock were used in the study: 10 adult males, 10 adult females, and 25 subadults which were surviving offspring from the primary family units of the previous year. Behavioral protocols and fecal samples were collected during Aug’04-Feb’05 and Aug’05-Feb’06. The family was observed for 1 hour and all agonistic interactions were recorded whereas feces were collected from all the individuals within the family for 3 hours. Results indicated that primary family groups (PF) were more common than secondary families (SF). Active social support was 38% of 4474 interactions in PF and 1.5% of 965 interactions in SF. Additionally, subadult males were more likely to win agonistic encounters than subadult females. Adult females in SF excreted less CORT than females whose young had not rejoined. Subadult females excreted less CORT during social density stress when rejoining their parents; yet this passive social support was neither detectable in adult nor in subadult males. This paper is important to understand the importance of primary and secondary families; and how social support helps inexperience young adults to establish themselves in the area.
This study was focused on the social support of primary families (parents raised concurrent young) and secondary families (parents did not raise concurrent young) of greylag goose by observing agonistics encounters and the extraction of corticosterone (CORT) in feces.
Data collection took place in River Alm, Upper Austria, Austria. 45 individuals from a 150 non-migratory greylag goose flock were used in the study: 10 adult males, 10 adult females, and 25 subadults which were surviving offspring from the primary family units of the previous year. Behavioral protocols and fecal samples were collected during Aug’04-Feb’05 and Aug’05-Feb’06. The family was observed for 1 hour and all agonistic interactions were recorded whereas feces were collected from all the individuals within the family for 3 hours. Results indicated that primary family groups (PF) were more common than secondary families (SF). Active social support was 38% of 4474 interactions in PF and 1.5% of 965 interactions in SF. Additionally, subadult males were more likely to win agonistic encounters than subadult females. Adult females in SF excreted less CORT than females whose young had not rejoined. Subadult females excreted less CORT during social density stress when rejoining their parents; yet this passive social support was neither detectable in adult nor in subadult males. This paper is important to understand the importance of primary and secondary families; and how social support helps inexperience young adults to establish themselves in the area.
Territoriality and Interspecific Interactions
The Golden Barrow’s Goldeneye is the only waterfowl species where both the male and female have been seen to defend their territories in summer and winter. In some places, the range of different species overlap and evolution has provided specializations of behavior and morphological adaptations which minimize the competition among two or more species. One of the most territorial and violent waterfowl is the Flying Steamer Duck. In1985, Neuchterlein and Storer saw male F. Steamer ducks killing Red shovelers and this behavior may be expressed not only due to the competition of food but also to show females their fighting abilities.
The Golden Barrow’s Goldeneye is the only waterfowl species where both the male and female have been seen to defend their territories in summer and winter. In some places, the range of different species overlap and evolution has provided specializations of behavior and morphological adaptations which minimize the competition among two or more species. One of the most territorial and violent waterfowl is the Flying Steamer Duck. In1985, Neuchterlein and Storer saw male F. Steamer ducks killing Red shovelers and this behavior may be expressed not only due to the competition of food but also to show females their fighting abilities.
Movements and Migrations
Monitoring migration
Monitoring birds has been challenge achieved by biologists in the last decades. The rapid evolution of technology has provided people with the right tools to track birds not only at a local scale but around the world. There are different ways to track waterfowl and the technique that has been commonly used among biologist is neck-collards and leg-bands. Other techniques such radio telemetry and radars have been use too but limited funding often make people to choose other cost-effective alternatives to answer their questions.
Monitoring birds has been challenge achieved by biologists in the last decades. The rapid evolution of technology has provided people with the right tools to track birds not only at a local scale but around the world. There are different ways to track waterfowl and the technique that has been commonly used among biologist is neck-collards and leg-bands. Other techniques such radio telemetry and radars have been use too but limited funding often make people to choose other cost-effective alternatives to answer their questions.
Interesting Facts:
"Since those initial days many new colonies have been established... In the 1950s there were only five known Barnacle geese colonies. By 1960 there were 11 colonies, increasing to 32 by 1980 and about 50 by 1996."
"Birds marked as goslings moved larger distances (mean 98.2 km) than those marked as adults (mean 69.8 km)
"Since those initial days many new colonies have been established... In the 1950s there were only five known Barnacle geese colonies. By 1960 there were 11 colonies, increasing to 32 by 1980 and about 50 by 1996."
"Birds marked as goslings moved larger distances (mean 98.2 km) than those marked as adults (mean 69.8 km)
Movement patterns
Arctic breeders: The typical waterfowl migration takes place from their breeding areas in the Arctic to more temperate areas in the United States and Mexico. Most species finish their journal in the Gulf Coast whereas some ducks such as Mallard move only until they find food.
Nomadic species: Some seasonal movements are related to rains and the flooding on wetlands in tropical species. In 1982, Frith studied the movement of the Australian Grey Teal and their response to floods in the area. Additionally, some other waterfowl species from tropical wetland show a very similar behavior towards these uncommon phenomena.
Changes in range: Most scientists agree that wildlife species are a good indicator of climate change and the response of waterfowl to these events in the shift in their migration routes and distribution ranges. A study by Kerbes in 1975 found out that the Lesser Snow Goose breeding distribution has extended South and West and this shift is attributed to the lack of food and agriculture in what is used to be their historic range.
Arctic breeders: The typical waterfowl migration takes place from their breeding areas in the Arctic to more temperate areas in the United States and Mexico. Most species finish their journal in the Gulf Coast whereas some ducks such as Mallard move only until they find food.
Nomadic species: Some seasonal movements are related to rains and the flooding on wetlands in tropical species. In 1982, Frith studied the movement of the Australian Grey Teal and their response to floods in the area. Additionally, some other waterfowl species from tropical wetland show a very similar behavior towards these uncommon phenomena.
Changes in range: Most scientists agree that wildlife species are a good indicator of climate change and the response of waterfowl to these events in the shift in their migration routes and distribution ranges. A study by Kerbes in 1975 found out that the Lesser Snow Goose breeding distribution has extended South and West and this shift is attributed to the lack of food and agriculture in what is used to be their historic range.
Timing and mechanisms of migration
Most birds travel very long distances in an exciting and amazing event better know as migration. As we already know, most waterfowl species migrate south from Canada to escape from the winter. Biologists have studied this behavior for many years but many questions about the mechanisms of migration still remain answered.
The moult migration: Moulting is an interesting characteristic in waterfowl because they become flightless usually at the end of the breeding season. Moult migration is the event in which waterfowl species congregate in numerous flocks to moult their primary and secondary flight feathers. This phenomenon is usually synchronized with the fledgling of their chicks.
Eclipse Plumage: Along with their moult migration, duck also go under a simultaneously mouit called Eclipse Plumage in which duck change their colorful plumage to a less conspicuous plumage similar to the females of their species. This process is seems to be an anti-predator behavior and last until the next breeding season.
Why they go North?
This question is being around for a long time and in late 1970s Drent and Owen (in two different studies) explained what they described as the "green wave" by studying Barnacle geese. The "green wave" concept suggests that geese follow the flush plant growth that can be up to three times their normal growth during the spring. By migrating northwards geese benefit from eating the most they can as they migrate north.
Most birds travel very long distances in an exciting and amazing event better know as migration. As we already know, most waterfowl species migrate south from Canada to escape from the winter. Biologists have studied this behavior for many years but many questions about the mechanisms of migration still remain answered.
The moult migration: Moulting is an interesting characteristic in waterfowl because they become flightless usually at the end of the breeding season. Moult migration is the event in which waterfowl species congregate in numerous flocks to moult their primary and secondary flight feathers. This phenomenon is usually synchronized with the fledgling of their chicks.
Eclipse Plumage: Along with their moult migration, duck also go under a simultaneously mouit called Eclipse Plumage in which duck change their colorful plumage to a less conspicuous plumage similar to the females of their species. This process is seems to be an anti-predator behavior and last until the next breeding season.
Why they go North?
This question is being around for a long time and in late 1970s Drent and Owen (in two different studies) explained what they described as the "green wave" by studying Barnacle geese. The "green wave" concept suggests that geese follow the flush plant growth that can be up to three times their normal growth during the spring. By migrating northwards geese benefit from eating the most they can as they migrate north.
Interesting Facts:
"As a consequence of seasonal fluctuation in food quality and abundance, high energy requirements can only be met during sharply demarcated periods of the year. By moving progressively North in spring, barnacle geese encounter a spring flush of plant growth three times. This supports the concept of the green wave."
"As a consequence of seasonal fluctuation in food quality and abundance, high energy requirements can only be met during sharply demarcated periods of the year. By moving progressively North in spring, barnacle geese encounter a spring flush of plant growth three times. This supports the concept of the green wave."
The Timing and mechanics of migration
Most waterfowl migrate south in the winter and north in the summer and the cues necessary for this massive event is due to different factors that the determine the best time for migration.
Photoperiod: Previous studies suggest that daylength is a determinant factor for birds to migrate. This hypothesis was supported through an accidental experiment at the Wildfowl and Wetlands Trust. Swans and other waterfowls are fed in the enclosure. This spectacle attracted a lot of people and the managers of this organization decided to extend the feeding hours by installing an external light source generator after sunset. Waterfowl were exposed to an extended daylength and therefore some birds started to migrating in the wrong time. The following picture describes the birds' departure under three different lighting regimes which was 6 weeks earlier that under normal light.
Most waterfowl migrate south in the winter and north in the summer and the cues necessary for this massive event is due to different factors that the determine the best time for migration.
Photoperiod: Previous studies suggest that daylength is a determinant factor for birds to migrate. This hypothesis was supported through an accidental experiment at the Wildfowl and Wetlands Trust. Swans and other waterfowls are fed in the enclosure. This spectacle attracted a lot of people and the managers of this organization decided to extend the feeding hours by installing an external light source generator after sunset. Waterfowl were exposed to an extended daylength and therefore some birds started to migrating in the wrong time. The following picture describes the birds' departure under three different lighting regimes which was 6 weeks earlier that under normal light.
Lehikoinen A. and Jaatinen K. 2012. Delayed autumn migration in northern European waterfowl. Journal of Ornithology 153:563-570
This is a long-term study that took place in the Hanko Bird Observatory in Finland from 1979 to 2009. Scientists studied the autumn migration of 15 northern European waterfowl species. Beginning, median, and end of migration were calculated annually for the 15 species from July to November. Years where less than 20 individuals where observed in the autumn were discarded, and mean migration distances were estimated by measuring the distance of the breeding areas to the wintering areas. They found that seven species showed significant changes in their autumn migration in the last decades. The graylag goose and the Eurasian wigeon delayed their autumn migration entirely. The Eurasian teal delayed the end of its migration, whereas, the Bean goose showed and advancement in the beginning of its migration. This paper supports the idea that global warming causes negative effects, and that waterfowl migration is a good indicator of this current event.
This is a long-term study that took place in the Hanko Bird Observatory in Finland from 1979 to 2009. Scientists studied the autumn migration of 15 northern European waterfowl species. Beginning, median, and end of migration were calculated annually for the 15 species from July to November. Years where less than 20 individuals where observed in the autumn were discarded, and mean migration distances were estimated by measuring the distance of the breeding areas to the wintering areas. They found that seven species showed significant changes in their autumn migration in the last decades. The graylag goose and the Eurasian wigeon delayed their autumn migration entirely. The Eurasian teal delayed the end of its migration, whereas, the Bean goose showed and advancement in the beginning of its migration. This paper supports the idea that global warming causes negative effects, and that waterfowl migration is a good indicator of this current event.
The extend of body reserves
Birds migrate for very long distances, some birds stop in their way and some do not; but in order to have a successful migration they need to have the right amount to energy and weight that allow them to complete their journey. Barnacle geese need about 250-300 grams of fat to use as fuel and differences in migration conditions ca have a substantial impact.
Birds migrate for very long distances, some birds stop in their way and some do not; but in order to have a successful migration they need to have the right amount to energy and weight that allow them to complete their journey. Barnacle geese need about 250-300 grams of fat to use as fuel and differences in migration conditions ca have a substantial impact.
Philopatry and Home ranges
In waterfowl usually the female return to her natal area to breed whereas the male follows. Female Buffleheads usually return to the same lake she was born and sometimes also uses the same tree to nest every year. This is behavior is also shown in some geese females that take their broods to feed in the sames pastures they were fed for the first time. Additionally, Ress (1987) studied Bewick's Swan and found that in swan's partners, males usually choose the are and the timing of the migration to the wintering grounds. She also found that during pre-flight behavior, males initiated and lead most movements while females began to led in the spring. The selection breeding grounds and migration is critical for the survival of the brood and the parents since the suitability of the areas change every year in north america. The figure on the right represents the Breeding Waterfowl Habitat Condition survey in 2011.
In waterfowl usually the female return to her natal area to breed whereas the male follows. Female Buffleheads usually return to the same lake she was born and sometimes also uses the same tree to nest every year. This is behavior is also shown in some geese females that take their broods to feed in the sames pastures they were fed for the first time. Additionally, Ress (1987) studied Bewick's Swan and found that in swan's partners, males usually choose the are and the timing of the migration to the wintering grounds. She also found that during pre-flight behavior, males initiated and lead most movements while females began to led in the spring. The selection breeding grounds and migration is critical for the survival of the brood and the parents since the suitability of the areas change every year in north america. The figure on the right represents the Breeding Waterfowl Habitat Condition survey in 2011.
Population Dynamics
Monitoring techniques
Monitoring waterfowl in North America is perhaps the most effective monitoring event in the world. Every year different crews in the United States and Canada go out and count waterfowl species. They spend a big amount of hours into this activity because the population size of each species is very important mainly for the new rules to be set for the upcoming hunting season. These population estimates (as any other estimate) are very sensitive to error with could result in the new listing of an endangered species if the error is constant. One of the main problem is the report species that were hunted because only a small portion of hunters report their game properly. A more effective way to track population growth is by leg bands and neck collars which are readable from large distance.
The estimates of waterfowl populations can be watched in the following video:
Monitoring waterfowl in North America is perhaps the most effective monitoring event in the world. Every year different crews in the United States and Canada go out and count waterfowl species. They spend a big amount of hours into this activity because the population size of each species is very important mainly for the new rules to be set for the upcoming hunting season. These population estimates (as any other estimate) are very sensitive to error with could result in the new listing of an endangered species if the error is constant. One of the main problem is the report species that were hunted because only a small portion of hunters report their game properly. A more effective way to track population growth is by leg bands and neck collars which are readable from large distance.
The estimates of waterfowl populations can be watched in the following video:
Peron G, Nicolai CA, and Koons DN. Demographic response to perturbations: the role of compensatory density dependence in a North American duck under variable harvest regulations and changing habitat. Journal of Animal Ecology 81:960-969.
This study on redheads (Aythya americana) was focused on the analysis of a 50+ years of data obtained from the GameBirds data base (Bird Banding Lab, USGS Patuxent Wildlife Research Center). Biologists were looking at the population density response to changes in breeding habitat availability (# ponds) and changes in harvest regulations (bag limit). The combination of capture-recovery, population surveys and age/sex ratios were integrated into population models to study the interaction between perturbations and density dependence. The results suggests that redhead population increased after wet years but decreases the following year suggesting that during the successful breeding year, the population size was above carrying capacity. Additionally, biologists did not find any significant pattern in population numbers and harvest regulations. This study is relevant for management implications because it shows that waterfowl populations are more impacted by habitat availability than by hunting.
This study on redheads (Aythya americana) was focused on the analysis of a 50+ years of data obtained from the GameBirds data base (Bird Banding Lab, USGS Patuxent Wildlife Research Center). Biologists were looking at the population density response to changes in breeding habitat availability (# ponds) and changes in harvest regulations (bag limit). The combination of capture-recovery, population surveys and age/sex ratios were integrated into population models to study the interaction between perturbations and density dependence. The results suggests that redhead population increased after wet years but decreases the following year suggesting that during the successful breeding year, the population size was above carrying capacity. Additionally, biologists did not find any significant pattern in population numbers and harvest regulations. This study is relevant for management implications because it shows that waterfowl populations are more impacted by habitat availability than by hunting.
Interesting Facts:
Only 16 foreign-marked individuals were detected in the wintering range of the Svalbard population, which is a small number given the 400,000 leg-band sightings during the study."
"In 42 of the 68% cases of emigration, the Svalbard-banded (Barnacle) geese returned in the same year (38%), following year (38%) or a subsequent year (24%).
Only 16 foreign-marked individuals were detected in the wintering range of the Svalbard population, which is a small number given the 400,000 leg-band sightings during the study."
"In 42 of the 68% cases of emigration, the Svalbard-banded (Barnacle) geese returned in the same year (38%), following year (38%) or a subsequent year (24%).
Recruitment
Recruitment is considered the stage at which the young of a duck, goose or swan begin to breed themselves. Animals when to start breeding and even when they are "capable" to breed, biologically speaking, they may decide not to if they consider that they are not ready to nest. Most geese and swan breed for the first time at age 3-5 or sometimes at the age of two as the earliest. Ducks usually breed for the time at age 2 and rarely 1 year. In order to reproduce successfully, geese need to gain experience and be vigilant for predator in the area. Waterfowl species have evolved and adopted different nesting strategies to avoid predation. These strategies include nesting in extreme sites such as cliffs, tree holes and sometimes in the present of larger predators. For example,one of the main predators of red-breasted goose is the arctic fox. Therefore, red-breasted geese (Branta ruficollis) nest nearby peregrine falcons' breeding areas up in Siberia because these raptors prey on arctic foxes.
One the eggs have survived the incubation process and hatched, the now have to face new challenge until they can finally fledged. Even though most ducklings spend most of the time on water they remain vulnerable to predators . For example, eiders broods suffer the loss of approximately 80% of duckling taken by gulls during the first two weeks from hatching.
Weather plays a critical factor on the breeding areas of waterfowl and stochastic environmental events can have a negative impact in the breeding success of all waterfowl.
Recruitment is considered the stage at which the young of a duck, goose or swan begin to breed themselves. Animals when to start breeding and even when they are "capable" to breed, biologically speaking, they may decide not to if they consider that they are not ready to nest. Most geese and swan breed for the first time at age 3-5 or sometimes at the age of two as the earliest. Ducks usually breed for the time at age 2 and rarely 1 year. In order to reproduce successfully, geese need to gain experience and be vigilant for predator in the area. Waterfowl species have evolved and adopted different nesting strategies to avoid predation. These strategies include nesting in extreme sites such as cliffs, tree holes and sometimes in the present of larger predators. For example,one of the main predators of red-breasted goose is the arctic fox. Therefore, red-breasted geese (Branta ruficollis) nest nearby peregrine falcons' breeding areas up in Siberia because these raptors prey on arctic foxes.
One the eggs have survived the incubation process and hatched, the now have to face new challenge until they can finally fledged. Even though most ducklings spend most of the time on water they remain vulnerable to predators . For example, eiders broods suffer the loss of approximately 80% of duckling taken by gulls during the first two weeks from hatching.
Weather plays a critical factor on the breeding areas of waterfowl and stochastic environmental events can have a negative impact in the breeding success of all waterfowl.
Mortality
The three major natural causes of mortality in animals are disease, starvation and predation.
Disease: Almost 1.8 million of waterfowl mortality has been granted to disease, especially outbreaks of botulism which is the main cause and fowl cholera the second main cause but way behind botulism.
Work TM, Klavitter JL, Reynolds MH and Blehert D. 2010. Avian Botulism: A case study in translocated endangered Laysan Ducks (Anas laysanensis) on Midway Atoll. Journal of Wildlife Diseases 46:499-506.
This study took place in Midway Atoll which is a National Wildlife Refuge located 1,930 kilometers from Honolulu, Hawaii. In an effort to increase the population Laysan ducks, 42 birds were translocated in 2005 and their population increased to 200 individuals by 2007. In August 2008, a large number of Laysan ducks were observed death in the area. The bodies were collected and necropsies were performed including external and internal examination of the carcasses. Botulism type C was confirmed in 81% of the examined carcasses. Results suggest that the outbreak of Botulism type C started 2-3 weeks earlier and lasted for less than 2 months. The most common lesions were diffuse red discoloration of the lungs, and mild bruising of the pectoral musculature. This study is a great example of the risks that endemic animals experience when they are introduced in other areas. Additionally, this epidemic point out that wildlife is still vulnerable even after some years that they were introduced, bringing up questions such as whether the benefit of conservation plan outweighs the costs.
Starvation: This mortality factor is difficult to measure because birds tend to fly further distances and explore other areas when food is scarce. The winter of 1962-1963 was one of the coldest in Europe and this event is the main explanation of the declines of hundreds of swans and other waterfowl species.
Predation: Less than 2% of waterfowl mortality is thought to be by the presence of predators. Most of the predator are mammals (nearly 70%) such as foxes, and others who prey more on dabbling ducks than geese and swans.
Sex and Age: Mortality differs in both sex and age. One of the main causes of males mortality is hunting because males are instrumentally considered "less valuable" for reproduction and also because their plumage make them an easy target. Females mortality is also high due to a greater stress exposure during the breeding season. Young are very vulnerable and therefore they become an easy target for predators. Adults have a higher survival rate and are only vulnerable few weeks a year during their moulting period.
The three major natural causes of mortality in animals are disease, starvation and predation.
Disease: Almost 1.8 million of waterfowl mortality has been granted to disease, especially outbreaks of botulism which is the main cause and fowl cholera the second main cause but way behind botulism.
Work TM, Klavitter JL, Reynolds MH and Blehert D. 2010. Avian Botulism: A case study in translocated endangered Laysan Ducks (Anas laysanensis) on Midway Atoll. Journal of Wildlife Diseases 46:499-506.
This study took place in Midway Atoll which is a National Wildlife Refuge located 1,930 kilometers from Honolulu, Hawaii. In an effort to increase the population Laysan ducks, 42 birds were translocated in 2005 and their population increased to 200 individuals by 2007. In August 2008, a large number of Laysan ducks were observed death in the area. The bodies were collected and necropsies were performed including external and internal examination of the carcasses. Botulism type C was confirmed in 81% of the examined carcasses. Results suggest that the outbreak of Botulism type C started 2-3 weeks earlier and lasted for less than 2 months. The most common lesions were diffuse red discoloration of the lungs, and mild bruising of the pectoral musculature. This study is a great example of the risks that endemic animals experience when they are introduced in other areas. Additionally, this epidemic point out that wildlife is still vulnerable even after some years that they were introduced, bringing up questions such as whether the benefit of conservation plan outweighs the costs.
Starvation: This mortality factor is difficult to measure because birds tend to fly further distances and explore other areas when food is scarce. The winter of 1962-1963 was one of the coldest in Europe and this event is the main explanation of the declines of hundreds of swans and other waterfowl species.
Predation: Less than 2% of waterfowl mortality is thought to be by the presence of predators. Most of the predator are mammals (nearly 70%) such as foxes, and others who prey more on dabbling ducks than geese and swans.
Sex and Age: Mortality differs in both sex and age. One of the main causes of males mortality is hunting because males are instrumentally considered "less valuable" for reproduction and also because their plumage make them an easy target. Females mortality is also high due to a greater stress exposure during the breeding season. Young are very vulnerable and therefore they become an easy target for predators. Adults have a higher survival rate and are only vulnerable few weeks a year during their moulting period.
The control of numbers
The numbers of swans, geese and ducks fluctuate naturally. However, this fluctuation can be also attributed to humans' lack of accuracy when they survey populations and also for the impact of hunting on waterfowl. Hunting pressure has increased around the world in the last centuries but we still a low impact on waterfowl because we also increased our crops that are also feeding birds. In North America, the levels of hunting are low; therefore, compensatory mortality (the taken of an individual that would have died by other circumstances anyways) is probably the rule in this case.
The numbers of swans, geese and ducks fluctuate naturally. However, this fluctuation can be also attributed to humans' lack of accuracy when they survey populations and also for the impact of hunting on waterfowl. Hunting pressure has increased around the world in the last centuries but we still a low impact on waterfowl because we also increased our crops that are also feeding birds. In North America, the levels of hunting are low; therefore, compensatory mortality (the taken of an individual that would have died by other circumstances anyways) is probably the rule in this case.
Conservation and Management
Problems with agriculture and fisheries
Conflicts between waterfowl and humans has increased in the last decades due to the increase of both humans and birds populations. They both demand more space but humans have decided that they have a priority over these lands. Thousands of hectares of suitable waterfowl habitat has been converted to crops, and cattle pastures.
Assessing damage: It is difficult to account for the monetary losses of farmers. In Canada, payments to farmers have reached up to 1.5 million dollars and 1.0 million dollars in management prevention plans. Here in Humboldt county, farmers have declared war to Aleutian geese. This once endangered species has increased in numbers from a few thousands in the early 80's to almost 100,000 birds in the last decade.
Preventing damage: Different alternatives have been proposed, some were applied but only few have worked. The US Fisheries and Wildlife Service has extended some hunting seasons and they have also increased bag limits of some geese and ducks. Some people and organizations have proposed a monetary discount/incentive for farmers in the areas where these species feed; like occurs in Canada and some countries in Europe.
Damage in fisheries: Waterfowl are accused for the decline of salmon and mollusks however, their impact is minimal compared to human industrialized fishing activity. Some waterfowl like mergansers prey on salmon and trout but their impact is hard to interpret because it overlaps with human harvest.
Conflicts between waterfowl and humans has increased in the last decades due to the increase of both humans and birds populations. They both demand more space but humans have decided that they have a priority over these lands. Thousands of hectares of suitable waterfowl habitat has been converted to crops, and cattle pastures.
Assessing damage: It is difficult to account for the monetary losses of farmers. In Canada, payments to farmers have reached up to 1.5 million dollars and 1.0 million dollars in management prevention plans. Here in Humboldt county, farmers have declared war to Aleutian geese. This once endangered species has increased in numbers from a few thousands in the early 80's to almost 100,000 birds in the last decade.
Preventing damage: Different alternatives have been proposed, some were applied but only few have worked. The US Fisheries and Wildlife Service has extended some hunting seasons and they have also increased bag limits of some geese and ducks. Some people and organizations have proposed a monetary discount/incentive for farmers in the areas where these species feed; like occurs in Canada and some countries in Europe.
Damage in fisheries: Waterfowl are accused for the decline of salmon and mollusks however, their impact is minimal compared to human industrialized fishing activity. Some waterfowl like mergansers prey on salmon and trout but their impact is hard to interpret because it overlaps with human harvest.
Interesting Facts:
"The change in vegetation on the traditional islands had a dramatic effect on goose distribution by geese being pushed towards low elevation salt marshes."
"If the geese were free to choose, no doubt they would spend most of the winter months at the farms offering the best food and least disturbance."
"The change in vegetation on the traditional islands had a dramatic effect on goose distribution by geese being pushed towards low elevation salt marshes."
"If the geese were free to choose, no doubt they would spend most of the winter months at the farms offering the best food and least disturbance."
Threatened Waterfowl
Waterfowl species usually migrate long distances and therefore their range tend to be very large. However, some species are endemic to islands like the Hawaiian goose their conservation is important. In the last century, 4 waterfowl species have become extinct mainly due to habitat loss: the Crested Shelduck, the Pink-headed duck, the Labrador duck, and the Auckland Islands Merganser.
There has been success stories in which some species were able to stabilize in numbers and saved from extinction. The Hawaiian goose (also known as Nene) is an endangered species whose population declined to less than 50 individuals in the wild in the 1940s. Nowadays, the nene population has increased to approximately 1200 individuals thanks to an intense breeding in captivity and reintroduction program implemented in the last 40 years. Also, the North American wood duck is another example of recovery thanks to the participation of federal organization and the public. The population of wood ducks was impacted primarily because this species nest in tree cavities in the forest. Deforestation impacted directly their reproduction success in the last decades but now their numbers are increasing again thanks to the nest boxes that are successfully replacing the tree cavities. Another success story is the Aleutian goose that was thought to be extinct by the early 1970s. One population of less than 800 hundred individuals was discovered in the Aleutian islands in the late 70s and the species was listed and protected under the Endangered Species Act (ESA). Today, the Aleutian goose population is estimated to be approximately 90,000 individuals.
Waterfowl species usually migrate long distances and therefore their range tend to be very large. However, some species are endemic to islands like the Hawaiian goose their conservation is important. In the last century, 4 waterfowl species have become extinct mainly due to habitat loss: the Crested Shelduck, the Pink-headed duck, the Labrador duck, and the Auckland Islands Merganser.
There has been success stories in which some species were able to stabilize in numbers and saved from extinction. The Hawaiian goose (also known as Nene) is an endangered species whose population declined to less than 50 individuals in the wild in the 1940s. Nowadays, the nene population has increased to approximately 1200 individuals thanks to an intense breeding in captivity and reintroduction program implemented in the last 40 years. Also, the North American wood duck is another example of recovery thanks to the participation of federal organization and the public. The population of wood ducks was impacted primarily because this species nest in tree cavities in the forest. Deforestation impacted directly their reproduction success in the last decades but now their numbers are increasing again thanks to the nest boxes that are successfully replacing the tree cavities. Another success story is the Aleutian goose that was thought to be extinct by the early 1970s. One population of less than 800 hundred individuals was discovered in the Aleutian islands in the late 70s and the species was listed and protected under the Endangered Species Act (ESA). Today, the Aleutian goose population is estimated to be approximately 90,000 individuals.
The Conservation of Wetlands
Wetlands are becoming more scarce in the last decades. Wetlands are usually very productive lands; therefore, most wetlands are being transformed into agriculture lands for the benefit human and for the disgrace of waterfowl and wildlife in general. It is very hard to stop economic growth in developing countries especially when agriculture is the best choice to escape from poverty. The first National Refuge was establishes in 1903. In order to maintain wetlands in North America, Canada, USA and Mexico signed the Migratory Bird Treaty to establish regulations in migratory waterfowl that spend time in these countries at some point of their lives. This treaty was very beneficial for waterfowl since only three countries had to agreed in order to protect all North America. This is something more complicated to achieve in Europe because countries are smaller and therefore migratory flocks visit many different nations.
Remaining threats
The world population has increased from 2 billion to 7 billion in the last century. This exponential growth makes almost impossible to stop agriculture expansion especially in developing countries.
In Africa, activities like burning and over grazing causes the declining of numbers of wetlands in many area. In Europe, the depletion of wetlands started hundred of years ago and became more intense in the last part of the century with the industrialization revolution making wetlands to almost disappear in the continent.
Furthermore, pollution has become a severe threat to wetlands. Pesticides are one of the main pollution factors for waterfowl population in the world because pesticides are washed off by rain and chemicals end up in the main streams that ultimate poison waterfowl and degrade their habitats. Another source of pollution is lead pellets. This type of ammunition is being slowly replaced by other less toxic alternatives, although is still used in some parts of the world. Poisoning from the ingestion of lead pellets is very common problem in waterfowl.
Wetlands are becoming more scarce in the last decades. Wetlands are usually very productive lands; therefore, most wetlands are being transformed into agriculture lands for the benefit human and for the disgrace of waterfowl and wildlife in general. It is very hard to stop economic growth in developing countries especially when agriculture is the best choice to escape from poverty. The first National Refuge was establishes in 1903. In order to maintain wetlands in North America, Canada, USA and Mexico signed the Migratory Bird Treaty to establish regulations in migratory waterfowl that spend time in these countries at some point of their lives. This treaty was very beneficial for waterfowl since only three countries had to agreed in order to protect all North America. This is something more complicated to achieve in Europe because countries are smaller and therefore migratory flocks visit many different nations.
Remaining threats
The world population has increased from 2 billion to 7 billion in the last century. This exponential growth makes almost impossible to stop agriculture expansion especially in developing countries.
In Africa, activities like burning and over grazing causes the declining of numbers of wetlands in many area. In Europe, the depletion of wetlands started hundred of years ago and became more intense in the last part of the century with the industrialization revolution making wetlands to almost disappear in the continent.
Furthermore, pollution has become a severe threat to wetlands. Pesticides are one of the main pollution factors for waterfowl population in the world because pesticides are washed off by rain and chemicals end up in the main streams that ultimate poison waterfowl and degrade their habitats. Another source of pollution is lead pellets. This type of ammunition is being slowly replaced by other less toxic alternatives, although is still used in some parts of the world. Poisoning from the ingestion of lead pellets is very common problem in waterfowl.
Creative conservation
Carrying capacity (k) is a term defined by the maximum number of individuals that a population can reach. This number (k) is reached in nature by different factors such as population size, predation, environmental events, etc. This number can be increased by wildlife managers if humans manage the factors that limit the population. In most cases, food is the limiting factor and this can be increased if biologists provide extra food to waterfowl through crops and large fields. Also, carrying capacity can be increased by removing predator of an islands of breeding areas to increase the probability of survival of juveniles.
Habitat creation: the creation of artificial wetlands is very important for conservation of waterfowl in our planet. A good example of wetlands creation takes us to Humboldt County, in the city of Arcata in northern California. The Arcata Marsh and Wildlife Sanctuary is chain of ponds and marshes created in the 1980s to treat the sewage that ends up in Humboldt bay. By creating this natural water treatment, waterfowl gained habitat rich in vegetation that allowed them not only to feed but also to nest and reproduce. This marsh have been very beneficial for the sake of and recreation of regular citizens and hunters.
Carrying capacity (k) is a term defined by the maximum number of individuals that a population can reach. This number (k) is reached in nature by different factors such as population size, predation, environmental events, etc. This number can be increased by wildlife managers if humans manage the factors that limit the population. In most cases, food is the limiting factor and this can be increased if biologists provide extra food to waterfowl through crops and large fields. Also, carrying capacity can be increased by removing predator of an islands of breeding areas to increase the probability of survival of juveniles.
Habitat creation: the creation of artificial wetlands is very important for conservation of waterfowl in our planet. A good example of wetlands creation takes us to Humboldt County, in the city of Arcata in northern California. The Arcata Marsh and Wildlife Sanctuary is chain of ponds and marshes created in the 1980s to treat the sewage that ends up in Humboldt bay. By creating this natural water treatment, waterfowl gained habitat rich in vegetation that allowed them not only to feed but also to nest and reproduce. This marsh have been very beneficial for the sake of and recreation of regular citizens and hunters.