Anas fulvigula

Geographic Range

Mottled ducks are found only in North America and are year-round residents. They are found in high densities in the intermediate marshlands of Louisiana and Southern Texas. Their population is very dense in the state of Florida from Alachua County to Cape Sable. However, they are found in the highest numbers in the wetlands around Lake Okeechobee and the areas around the Upper St. Johns River. They are also found in small numbers around the Gulf of Mexico, Alabama and the Mississippi coastal borders (approximately one-eighth of the population). A very small population was found as far south as Vera Cruz, Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

In Florida, mottled ducks are found in freshwater wetlands, ditches, wet prairies and flooded marshes. In some seasons, mottled ducks are also found in rice and flooded fallow fields. In some cases, they have been found in small numbers in mosquito control areas. They stay in the same area year-round.

In Texas and Louisiana, mottled ducks are found fresh and saltwater marshes and brackish ponds. These areas are full of vegetation such as bulrush, long grasses, rice, cutgrass and bultongue.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools
• coastal coastal
• brackish water brackish water

• Wetlands
• marsh marsh

• Other Habitat Features
• estuarine estuarine

Physical Description

Mottled ducks are brown and are not easily distinguished from American black ducks ( Anas rubripes ). They have an iridescent blue speculum and buffy plumage, which makes them appear lighter than other species. They lack a few features that other ducks have such as white anterior edges on the speculum. These ducks appear to be uniformly dark from a distance. Mottled ducks are sexually dimorphic. The bills of males are bright yellow, but are drab colored in females. The females are grayer whereas the males are very brown in color. The tails of the males have a faint pattern but the tails of the females are patternless. Both sexes have blackish-brown upper sides and undersides. Both also have a smoke-gray U-shaped stripe on their undersides. They weigh from 810 to 1330 g and are 50 to 61 cm long with wingspans from 243 to 270 cm. Males tend to be larger than females.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful

Reproduction

Pair formation begins as early as March. Pairs usually break-up shortly after the eggs are laid and incubation begins. The ducks are monogamous during the breeding season. They are not monogamous for life, however. Each season new pairs are formed. They engage in many courtship displays which include: head-shakes (the male simply shakes his head in the females direction), intro-shakes (the male, to gain the female's attention, treads water then rises above the water and shakes his head), grunt-whistles (the male places his bill in the water, pulls it up while making noise and splashes the water in the air), inciting (the female performs this display for the male after the pair has formed), preen-behind-wing (fake preening).

This whole display takes only about three minutes. The ducks also have another courtship ritual in which the male swims around the female, pulling his head in and out of the water; this behavior is known as bridling.

• Mating System
• monogamous monogamous

Mottled ducks breed once yearly. Eighty percent have formed pairs by November and mating begins in January. The nests are made of matted grass and are on the ground or suspended over shallow water and are in dense grasses. Females lay 5 to 13 eggs per clutch. The eggs take 24 to 28 days to hatch. The ducks fledge after 45 to 56 days. They are independent adults in 65 to 70 days. Both males and females are sexually mature in one year.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

After the eggs hatch, the females lead the brood from the nest. The ducklings are precocial and are able to find their own food. They tend to eat invertebrate larvae when available. The mothers care for the young approximately 20% of the day. The mother spends 34% of her time feeding, 28% resting, 11% preening and 20% watching for predators. The females give alarm calls if an intruder approaches the nest or her young. Broods tend to gather together at night to keep safe. The females usually stay with the ducklings until they can fly (about 45 to 56 days).

• Parental Investment
• precocial precocial
• pre-hatching/birth
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Mottled ducks have relatively short lifespans, on average they live for only 2 years. They have an annual mortality rate of about 50%. The longest known lifespan in the wild is thirteen years. The expected lifespan in the wild is five years. The expected lifespan in captivity is twenty years.

Behavior

Mottled ducks have the ability to walk well on land (waddling) and are strong swimmers. They have strong, deep wing beats which result in direct and slow flight. In general, males are more aggressive than females, except when females have young. Their territories are usually 10 to 130 m^2, but are generally 40 m^2.

Mottled ducks have many behaviors to show aggression or fear, including: bill threats (the bird raises its beak to ward off predators and intruders), chasing, biting, inciting (when an unpaired female turns her head toward males to gain their attention), gesture-of-repulsion (a female holds her head close to her body and remains in a crouched position to ward off potential and unwanted mates), extra-pair copulation flights (a male tries to overtake/overpower a female that is not his usual mate) and pursuit flights (two males try to overtake one female in order to mate).

• Key Behaviors
• flies
• diurnal diurnal
• motile motile
• territorial territorial
• social social

Home Range

We do not have information on home range for this species at this time.

Communication and Perception

Mottled ducks communicate with each other by making noise and displaying (see Mating Systems and Behavior).

Their sounds resemble those of mallards. The males have a low raspy "“raeb"” call. A single call note is an alarm signal and two notes together signify either courtship or conversational calls. The females also have a low, raspy call. It starts out high pitched and lowers in pitch throughout the call. Female calls consist of six notes, the second one is the highest pitched. When the female is alerted, she lets out three or four quick quacks. The female uses a "gagg" note when she is inciting (attracting) her mate.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Mottled ducks are carnivors and herbivores. They eat aquatic invertebrates and small fish. They often eat snails, crayfish, beetles, dragonfly nymphs, fish and midge larvae. Invertebrates make up from 1 to 40 percent of their diet. They also eat seeds, grasses, aquatic vegetation and rice.

Mottled ducks usually feed in pairs in the fall and winter. During the summer, they may feed in small groups of about twenty. From August through October (especially in the rice fields) they often feed in flocks of around three thousand. When the ducks feed alone, they search the marshlands for seeds and invertebrates by sitting on the water and tipping their heads under water (a behavior called dabbling). They rarely dive for food, but when they do, it is for minnows.

• Primary Diet
• omnivore omnivore

• Animal Foods
• mammals
• fish
• eggs
• insects
• mollusks
• aquatic or marine worms
• aquatic crustaceans

• Plant Foods
• leaves
• seeds, grains, and nuts

Predation

To escape from predators, most adults fly away. If they are ducklings and molting adults and are unable to fly, they dive underwater or hide in brush. The adult females are very protective of their broods and quack loudly at any approaching intruders.

Mammalian predators feed on eggs, nesting females, ducklings and adults during molting season. Some of these predators include gray fox ( Urocyon cinereoargenteus ), red fox ( Vulpes vulpes ), American mink ( Mustela vison ), river otters ( Lontra canadensis ), striped skunks ( Mephitis mephitis ), ground squirrels (genus Spermophilus ) and raccoons ( Procyon lotor ). Northern harriers ( Circus cyaneus ) and peregrine falcons ( Falco peregrinus ) also prey on mottled ducks. In Florida, alligators ( Alligator mississippiensis ) eat the ducklings and some flightless adults. Snapping turtles ( Chelydra serpentina ), bullfrogs ( Rana catesbeiana ) and bass ( Micropterus salmoides ) also prey on ducklings.

Ecosystem Roles

Mottled ducks eat aquatic invertebrates and small fish, and help to regulate their populations. Mammals, birds of prey and other animals eat mottled ducks and help regulate their population. Their consumption of vegetation around their habitats prevents over-growth of these plants.

Economic Importance for Humans: Positive

Mottled ducks often help control mosquito populations and are hunted by humans for food. In addition, their feathers are used to make a good quality down.

• Positive Impacts
• food food
• body parts are source of valuable material
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse affects of mottled ducks on humans.

Conservation Status

In Florida, mottled ducks have lost 3.7 million acres of wetland habitat due to drainage for citrus orchards and improved pastures for cattle. In Texas and Louisiana, many of the wetlands have been depleted as a result of industrialization, urbanization, coastal erosion and drainage (approximately 102 to 150 sqaure kilometers are destroyed per year). Feral mallard ducks (which are kept as pets) mate with mottled ducks, which decreases the number of pure mottled ducks in the population. Mottled ducks also tend to breed with other species of ducks, which also decreases their genetic representation in the population. The effects of hunting are undetermined for this species.

Mottled ducks are protected under the US Migratory Bird Treaty Act.

Additional Links

Encyclopedia of Life

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Megan Shetney (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

References

CITES, 2004. "Convention on International Trade In Endangered Species of Wildlife Flora and Fauna" (On-line). CITES. Accessed April 28, 2004 at http://www.cites.org .

Florida Fish and Wildlife, 2004. "An Introduction to Florida's Mottled Duck" (On-line). Accessed April 28, 2004 at http://www.wildflorida.org/duck/Mottled_Ducks/mottled_duck.htm .

Moorman, T., P. Gray. 1994. Mottled duck (Anas fulvigula). Pp. 1-20 in The Birds of North America , Vol. 81. The Academy of Natural Sciences, Philadelphia, and The American Ornithologist's Union, Washington, D.C.

NatureServe, 2003. "Nature Serve Explorer" (On-line). Accessed April 28, 2004 at http://www.natureserve.org/explorer/statusus.htm .

Pranty, B. 2002. "Mottled Duck (Anas fulvigula)" (On-line). Florida's Breeding Atlas. Accessed April 28, 2004 at http://www.wildflorida.org/bba/modu.htm .

The American Ornithologists Union, 1992. Handbook of Birds of the World . Barcelona: Lynx Editions.

USGS, 2002. "Biological and Ecotoxicological Characteristics Of Terrestrial Vertebrate Species Residing In Estuaries" (On-line). Accessed April 28, 2004 at http://www.pwrc.usgs.gov/bioeco/mduck.htm .