Selected Birds of the Boreal Forest of North America



American White Pelicans
© Chuck Gordon



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Arrows represent general migration routes.
The arrows do not necessarily link specific
breeding and wintering grounds.
American White Pelican
Pelecanus erythrorhynchos

Few can fail to be impressed by the sight of this spectacular species, one of the largest boreal birds, soaring overhead or feeding in synchronized groups.  This species is something of a conservation success story, with major population declines and range contractions before 1980 largely reversed.

Habitat
The American White Pelican is dependent on wetlands for its survival, and the boreal forest provides plenty.  It nests on islands in freshwater and saline lakes, foraging in shallow waters up to 50 kilometers (30 miles) or more away.  It uses similar foraging sites during migration to its largely coastal wintering sites.  Preferred winter habitats are shallow bays, inlets, and estuaries containing suitable prey and loafing sites; it also can be seen on man-made ponds and lagoons. 

Diet/Feeding Behavior
Like all pelicans, the American White Pelican is primarily a fish eater.  Its usual prey species are  small schooling fish, but it also eats some bottom feeders; within the preferred size range, it is non-selective, taking prey purely on the basis of availability.  It also takes salamanders and crayfish opportunistically.  The species often uses a characteristic group feeding strategy wherein a flock will form a circle or semi-circle and, using coordinated bill dipping and wing beating, drive prey toward shore where it is more easily caught.  It also forages individually but with lower success; foraging behavior tends to shift toward cooperation when prey aggregations are located.  It commonly forages at night during the breeding season, using tactile means of locating prey; daytime foraging is probably more visual.  This species never plunge-dives like the Brown Pelican (Pelecanus occidentalis).  Daily food intake of breeding adults may reach 40 percent of body mass.  White Pelicans often steal prey from one another and from other species, especially diving birds in deeper waters.

Breeding
The American White Pelican breeds in a dozen or so disjunct areas.  The largest of these extends from the southern fringes of the boreal forest in the Canadian prairie provinces south through the prairies and high plains to Montana and South Dakota.  Other populations are scattered through the Great Basin, Intermountain, and Plains regions from British Columbia and Ontario to California and Colorado.  Non-migratory populations occur in Texas and Mexico.  This species is seasonally monogamous, pairing quickly after arrival at breeding sites.  Courtship consists of circular flights over the nesting site, often with other individuals, and a variety of displays on the ground, including strutting, bowing, and head swaying.  Sub-colonies form and grow as individuals are attracted and stimulated by the breeding activities of their neighbors.  The nest is merely a shallow depression, the rim often barely sufficient to keep eggs and chicks from rolling out.  Two eggs are laid; incubation is by both parents equally, in two-day shifts, and lasts about 30 days.  The young are born naked and blind, but their eyes open within a day.  Parents regurgitate food for the young, onto the ground or their feet at first; thereafter the parents regurgitate the food to their own bill tip, then only within their pouch, and finally only into their own throat, whence the young remove it.  The first-hatched chick usually harasses its younger sibling until the latter dies of starvation.  The parents alternate between brooding and foraging, switching daily, for about 17 to 25 days, after which the surviving young begin leaving the nests and forming  creches while both parents forage.  Initially, the young return to their nests from the creches to eat and to be brooded at night, but as they get older they become less attached to the nest. The young take their first flights at about 9 to 10 weeks of age and leave the colony soon thereafter.

Migration/Winter Range
American White Pelicans segregate well into two separate geographic groups.  Populations breeding east of the Rocky Mountains migrate south and east, mostly along river valleys, to winter along the Gulf of Mexico.  Populations west of the Rockies migrate over deserts and mountains to the Pacific coast.  Migration occurs mainly during daylight in flocks sometimes numbering in the hundreds, often flying in the familiar V-formation and using thermals when available.  Fall migration is protracted, with individuals lingering on southerly breeding grounds as late as December in mild winters.  Spring arrival on breeding grounds is as early as February in Nevada, March in Utah, and April in Wyoming and Manitoba, usually before lakes but after rivers have thawed, providing some foraging sites even if nest sites are inaccessible.  Large numbers of migrating pelicans can be seen in fall at Horicon National Wildlife Refuge in Wisconsin; in spring at Deer Flat National Wildlife Refuge in Idaho; and in both seasons at Cheyenne Bottoms Wildlife Area in Kansas and Sand Lake National Wildlife Refuge in South Dakota.

Conservation Issues and Status
American White Pelican populations declined and  the species' breeding range contracted markedly during much of the  20th century, due to a combination of shooting, disturbance of nesting colonies, fluctuations in water levels, and perhaps pesticides.  The species was a popular sport- and trophy-shooting object and also was persecuted misguidedly as a competitor for valuable fish.  Hydroelectric projects flooded many nesting sites, and droughts made others vulnerable to predation.  Increases in water-oriented recreation caused many colonies to be abandoned.  Organochlorine pesticides such as DDT caused eggshell thinning.  Most of these problems have been addressed, and populations have recovered in most areas in recent decades, allowing many abandoned breeding sites to be re-colonized and new ones to be established, though the species has not returned to some historic nesting areas.  Breeding Bird Survey data show a 4.8 percent annual increase survey-wide since 1980, with the largest increase in the Midwest and no significant declines anywhere.  The boreal population may be increasing slightly.  The Christmas Bird Count also has shown a strong increase, especially in Texas.  However, the species is still vulnerable because breeding colonies are so sensitive to disturbance and vulnerable to changes in water levels.  Large-scale fish die-offs, often caused by water pollution, and outbreaks of diseases such as avian cholera and botulism, a frequent result of over-crowding due to habitat loss, also take heavy tolls.

References

Evans, R. M., and K. J. Cash.  1985.  Early spring flights of American White Pelicans: Timing and functional role in attracting others to the breeding colony.  Condor 87:252-255.

Evans, R. M., and F. L. Knopf.  1993.  American White Pelican (Pelecanus erythrorhynchos).  In The Birds of North America, No. 57 (A. Poole and F. Gill, Eds.).  Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.

Evans, R. M., and B. F. McMahon.  1987.  Within-brood variation in growth and condition in relation to brood reduction in the American White Pelican.  Wilson Bull. 99:190-201.

Knopf, F. L.  1979.  Spatial and temporal aspects of colonial nesting of White Pelicans.  Condor 81:353-363.

National Audubon Society.  2002.  The Christmas Bird Count Historical Results [Online]. http://www.audubon.org/bird/cbc.

Sauer, J. R., J. E. Hines, and J. Fallon.  2003.  The North American Breeding Bird Survey, Results and Analysis 1966-2002, Version 2003.1, USGS Patuxent Wildlife Research Center, Laurel, MD.

Sidle, J. G., W. H. Koonz, and K. Roney.  1985.  Status of the American White Pelican: an update.  Amer. Birds 39:859-864.

Birding content provided by National Wildlife Federation/eNature with support from Ducks Unlimited/The Pew Charitable Trusts

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