Redheads are diving ducks, with even small ducklings capable of diving to obtain most of their food. During the breeding and post-breeding seasons Redheads gather submerged freshwater vegetation and supplement this diet with aquatic invertebrates. In wihter in coastal lagoons and bays these ducks feed on the rhizomes of emergent grasses, with added nutrition from mollusks (Woodin and Michot 2002).
Female Redheads commonly lay eggs in other Redhead nests and less frequently in nests of other duck species as well as nests in which a number of Redhead females lay eggs. A female may adopt one of 3 strategies: laying a clutch, parasitizing other nests before laying a clutch , or parasitizing other duck nests without producing a clutch (Woodin and Michot 2002).
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, observers found 5 confirmed, 16 probable and 11 possible records for Redheads, primarily on the High Plains, plus a few in El Paso County in the extreme west Trans-Pecos (see the region map in Lockwood and Freeman ). North American Breeding Bird Survey (BBS) volunteers found Redheads on 3 routes in the Panhandle at a relative abundance of <1 duck per 40 km (25 mi) route (Sauer et al. 2008). In Oklahoma atlasers found 14 probable breeding locations in the western part of the state (Versaw 2004).
BBS observers found most Redheads breeding on the Canadian prairies and in the United States in the Dakotas, eastern Washington, southern and eastern Oregon, northern California, central Nevada and northern and western Utah (Sauer et al. 2008). Some Redheads are present year-round in the central volcanic belt of Mexico. Most Redheads winter along the Gulf Coast with others scattered from southwest Canada through the lower 48 United States, most of Mexico and some Caribbean islands (Howell and Webb 1995, Am. Ornithol. Union 1998, Woodin and Michot 2002).
SEASONAL OCCURRENCE. Redheads are uncommon to common migrants throughout Texas, arriving as early as September 3 with most present by mid-October. In winter they are common to abundant along the central and lower coast, especially in the Laguna Madre. They are also locally common in the rest of the state. Across North America most Redheads depart between late January and mid-March. Most breeding occurs from mid-May through Augus (Oberholser 1974,Woodin and Michot 2002, Lockwood and Freeman 2004).
BREEDING HABITAT. In Colorado more than half of breeding evidence for Redheads came from the presence of fledged young on lakes with the rest from sightings of young on wetlands with floating or emergent vegetation (Boyle 1998). Breeding evidence was obtained in similar habitats in Arizona (Bradley 2005).
Nests of Redheads are usually placed in tall, dense emergent vegetation over standing water. The female starts building the nest one to several days before laying the first egg. She gathers dead cattail blades and similar materials near the nest site, then breaks them into sections and weaves them into a neat basket supported by live plants (see photo in Harrison ). The nest is lined with bits or emergent plants mixed with down feathers (Harrison 1979, Woodin and Michot 2002).
In this basket the female lays an egg a day until a clutch of about 10-11 (range 7-14) creamy white to pale olive buff eggs is complete. Determining accurate clutch sizes is extremely difficult due to a strong tendency of female Redheads to lay eggs in nests of other Redheads. Females also lay in nests of other ducks or “dump nests,” visited by as many as 13 females. These nests are rarely incubated, but a female Redhead sat on a nest with 44 eggs, only one of which hatched successfully. In a normal nest the female incubates the eggs for 24-25 (range 22-28) days. Newly hatched precocial ducklings begin feeding before departing with their mother for a larger body of water. Here they grow and develop until they can fly, about 6-8 weeks after the ducklings hatched. Most hens abandon their broods before then (Woodin and Michot 2002).
STATUS. Before 1974 only one nest of a Redhead had been reported in Texas (Oberholser 1974). These ducks are now fairly rare breeders in the western Trans-Pecos and Panhandle although they are uncommon to locally common summer residents in the later region (Lockwood and Freeman 2004).
BBS data from 3 routes in Texas are inadequate to provide a biologically meaningful trend, but data from 341 routes across North America suggest little change in Redhead populations has occurred since 1980 (Sauer et al. 2008). This information and the extent of the wintering population in the :Laguna Madre suggests Redheads will be a part of the Texas avifauna for many years.
Text by Robert C. Tweit (2008)
American Ornithologists’ Union. 1998. Checklist of North American birds, 7th ed. Am, Ornithol. Union, Washington, DC.
Boyle, S.. 1998. Redhead (Aythya americana). In Colorado breeding bird atlas, pp. 90-91 (H. E. Kingery, ed.), Colorado Bird Atlas Partnership, Denver.
Bradley, B. 2005. Redhead (Aythya americana). In Arizona breeding bird atlas. pp. 68-69 (T. E. Corman and C. Wise-Gervais, eds.), University of New Mexico Press, Albuquerque.
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, New York.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Sauer, J. R., J. E. Hines, and J. Fallon. 2008. The North American breeding bird survey, results and analysis 1966-2007. Version 5.15.2008. USGS Patuxent Wildlife Research Center, Laurel MD < http://www.mbr-pwrc.usgs.gov/bbs>
Versaw, A. E. 2004. Redhead (Aythya americana). In Oklahoma breeding bird atlas, pp. 78-79 (D. L. Reinking, ed.). University of Oklahoma Press, Norman.
Woodin, M. C. and T. C. Michot. 2002. Redhead (Aythya americana), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from: http://bna.birds.cornell.edu/bna/species/695