White Pelican Research Articles

Demographics of Piscivorous Colonial Waterbirds and Management Implications for ESA-listed Salmonids on the Columbia Plateau

We investigated colony size, productivity, and limiting factors for five piscivorous waterbird species nesting at 18 locations on the Columbia Plateau (Washington) during 2004–2010 with emphasis on species with a history of salmonid (Oncorhynchus spp.) depredation. Numbers of nesting Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus) were stable at about 700–1,000 breeding pairs at five colonies and about 1,200–1,500 breeding pairs at four colonies, respectively. Numbers of American white pelicans (Pelecanus erythrorhynchos) increased at Badger Island, the sole breeding colony for the species on the Columbia Plateau, from about 900 individuals in 2007 to over 2,000 individuals in 2010. Overall numbers of breeding California gulls (Larus californicus) and ring-billed gulls (L. delawarensis) declined during the study, mostly because of the abandonment of a large colony in the mid-Columbia River. Three gull colonies below the confluence of the Snake and Columbia rivers increased substantially, however. Factors that may limit colony size and productivity for piscivorous waterbirds nesting on the Columbia Plateau included availability of suitable nesting habitat, interspecific competition for nest sites, predation, gull kleptoparasitism, food availability, and human disturbance. Based on observed population trends alone, there is little reason to project increased impacts to juvenile salmonid survival from tern and cormorant populations. Additional monitoring and evaluation may be warranted to assess future impacts of the growing Badger Island American white pelican colony and those gull colonies located near mainstem dams or associated with Caspian tern colonies where kleptoparasitism is common.

West Nile Virus Transmission in Winter: The 2013 Great Salt Lake Bald Eagle and Eared Grebes Mortality Event

West Nile Virus (WNV) infection has been reported in over 300 species of birds and mammals. Raptors such as eagles, hawks and falcons are remarkably susceptible, but reports of WNV infection in Bald Eagles (Haliaeetus leucocephalus) are rare and reports of WNV infection in grebes (Podicipediformes) even rarer. We report an unusually large wild bird mortality event involving between 15,000-20,000 Eared Grebes (Podiceps nigricollis) and over 40 Bald Eagles around the Great Salt Lake, Utah, in November-December 2013. Mortality in grebes was first reported in early November during a period when the area was unseasonably warm and the grebes were beginning to gather and stage prior to migration. Ten out of ten Eared Grebes collected during this period were WNV RT-PCR and/or isolation positive. This is the first report of WNV infection in Eared Grebes and the associated mortality event is matched in scale only by the combined outbreaks in American White Pelican (Pelecanus erythrorhynchos) colonies in the north central states in 2002-2003. We cannot be sure that all of the grebes were infected by mosquito transmission; some may have become infected through contact with WNV shed orally or cloacally from other infected grebes. Beginning in early December, Bald Eagles in the Great Salt Lake area were observed to display neurological signs such as body tremors, limb paralysis and lethargy. At least 43 Bald Eagles had died by the end of the month. Nine of nine Bald Eagles examined were infected with WNV. To the best of our knowledge, this is the largest single raptor mortality event since WNV became endemic in the USA. Because the majority of the eagles affected were found after onset of below-freezing temperatures, we suggest at least some of the Bald Eagles were infected with WNV via consumption of infected Eared Grebes or horizontal transmission at roost sites.

Indirect Cannibalism by Crèche-aged American White Pelican (<em>Pelecanus erythrorhynchos</em>) Chicks

At nesting colonies of American White Pelicans (Pelecanus erythrorhynchos), many chicks die from siblicide, severe weather, and disease; this results in carcasses available for scavenging by conspecifics (i.e., indirect cannibalism). Indirect cannibalism has not been reported previously for this species. We describe five cases of crèche-aged American White Pelican chicks consuming or attempting to consume dead younger chicks at two nesting colonies in the northern plains of North America. Cannibalism in the American White Pelican appears to be rare and likely plays no role in the species’ population ecology or dynamics; however, it might be an important survival strategy of individual chicks when food resources are limited.

Evaluation of Methods for Collecting Blood-Engorged Mosquitoes from Habitats Within a Wildlife Refuge

Mortality of American white pelican (Pelecanus erythrorhynchos) chicks attributed to West Nile virus (WNV) prompted field studies on the bionomics of mosquitoes on a wildlife refuge in northern Montana. One component of these studies was to identify blood meal sources for Culex tarsalis, the primary vector of WNV in the region, and the potential bridge vectors Aedes vexans and Culiseta inornata. To accomplish this, 3 methods were evaluated to collect bloodfed mosquitoes: a gasoline powered aspirator, CO2-baited light traps, and fiber pots in shelterbelts consisting of stands of deciduous trees and shrubs and marshes along the lake edge. Fiber pots were also deployed in open fields of prairie grasses. Overall, fiber pots were the most efficient method for collecting engorged Cx. tarsalis and Cs. inornata, largely due to shorter sampling and processing times. Aedes vexans was not collected in fiber pots but was more abundant in aspiration samples than the other 2 species. The optimal location for collecting Cx. tarsalis was dependent on trapping method. Aspirations and fiber pot placements collected more Cx. tarsalis in shelterbelts, while CO2-baited light traps collected more Cx. tarsalis in the marsh habitat. Sixteen avian and 4 mammalian hosts were identified from bloodfed Cx. tarsalis with 46 blood meals derived from birds and 49 from mammals. Aedes vexans and Cs. inornata fed predominantly on white-tailed deer (Odocoileus virginianus) and cattle (Bos taurus), respectively. Humans were identified as hosts in 33% of engorged Cx. tarsalis, 4% of engorged Ae. vexans, and 18% of engorged Cs. inornata.

Hepatitis and splenitis due to systemic tetratrichomoniasis in an American white pelican (Pelecanus erythrorhynchos)

A free-ranging, young adult, female American white pelican (Pelecanus erythrorhynchos), found dead on the grounds of the San Diego Zoo Safari Park in Southern California, had severe multifocal to coalescing necrotizing hepatitis and splenitis on postmortem examination. Histologically, within the large areas of necrosis were myriad pleomorphic, 5-20 µm in diameter, protozoal organisms with 1 to multiple nuclei. Ultrastructurally, the organisms were consistent with a trichomonad flagellate. Polymerase chain reaction and sequencing of the small subunit ribosomal RNA gene identified nucleotide sequences with 99% identity to Tetratrichomonas gallinarum, which is a common inhabitant of the intestinal tract of galliform and anseriform birds that has occasionally been associated with disease, including typhlitis and hepatitis. Damage to the cecal mucosa in the pelican from trematodes and secondary bacterial infection could have allowed invasion and systemic dissemination of the organism. Exposure of the pelican to a variety of native and exotic anseriform and galliform birds at the zoological institution could have led to cross-species infection and severe manifestation of disease in a novel host.

Mosquito and West Nile virus surveillance in northeast Montana, U.S.A., 2005 and 2006

Mosquito and West Nile virus (WNV) surveillance was conducted on a national wildlife refuge in northeast Montana in 2005 and 2006, during which outbreaks of WNV in a colony of American white pelicans (Pelecanus erythrorhynchos Gmelin) (Pelecaniformes: Pelecanidae) resulted in juvenile mortality rates of ∼ 31%. Both years, floodwater species Ochlerotatus dorsalis (Meigen) (Diptera: Culicidae), Aedes vexans (Meigen) (Diptera: Culicidae) and Ochlerotatus flavescens (Muller) (Diptera: Culicidae) comprised 78% of the total collection and heightened host-seeking activity was observed from mid-June to mid-July. Culex tarsalis Coquillett (Diptera: Culicidae) was most active from mid-July to mid-August and comprised 18% of the collection in 2005 and 20% in 2006. However, fewer than 10% of the Cx. tarsalis females collected in 2006 were obtained adjacent to the pelicans' nesting grounds. Minimum infection rates per 1000 Cx. tarsalis tested for WNV were 1.36 in 2005 and 1.41 in 2006. All pools in which WNV was detected in 2006 were composed of females collected 10 km from the nesting grounds. Substantial juvenile pelican mortality in 2006 despite reductions in the population of the primary vector and in mosquito infection rates near the colony suggests that the methods used to detect the introduction of WNV were too coarse and that amplification of the virus within the colony may reflect causes other than mosquito infection.

West Nile Virus in American White Pelican Chicks: Transmission, Immunity, and Survival

West Nile virus (WNV) causes significant mortality of American White Pelican chicks at northern plains colonies. We tested oropharyngeal/cloacal swabs from moribund chicks for shed WNV. Such shedding could enable chick-to-chick transmission and help explain why WNV spreads rapidly in colonies. WNV was detected on swabs from 11% of chicks in 2006 and 52% of chicks in 2007; however, viral titers were low. Before onset of WNV mortality, we tested blood from < 3-week-old chicks for antibodies to WNV; 5% of chicks were seropositive, suggesting passive transfer of maternal antibodies. Among near-fledged chicks, 41% tested positive for anti-WNV antibodies, indicating that they survived infection. Among years and colonies, cumulative incidence of WNV in chicks varied from 28% to 81%, whereas the proportion of chicks surviving WNV (i.e., seropositive) was 64-75%. Our data revealed that WNV kills chicks that likely would fledge in the absence of WNV, that infection of chicks is pervasive, and that significant numbers of chicks survive infection.

МОДЕЛЮВАННЯ ЕНЕРГЕТИЧНИХ ПАРАМЕТРІВ, ШВИДКОСТІ ТА МІГРАЦІЙНИХ ДИСТАНЦІЙ ПТАХІВ

&lt;p&gt;The results of the preliminary analysis carried out by &lt;em&gt;Flight&lt;/em&gt; software for White Stork and Pelican that migrate within the Mediterranean-Black Sea Migratory Route were presented. Obtained results practically coincide with experimental results and data of radar observations. Optimum speed allows the birds to fly with a higher grade soaring and shorter distance between the thermal flows. Time to find the next effective thermals (thermal flux) is reduced by increasing the speed, which in turn reduces the average rise in thermal flows, increases the risk not to find appropriate thermal. Soaring birds reduce wingspan and wing area by bending the joints of the extremities at high speeds. This reduces profile resistance and increases the inductive reactance. Profile resistance increases and the inductive reactance decreases with increasing of bird speed. Under ideal conditions the birds try to find a position of wingspan, which reduces the difference between the values ​​of profile and inductive resistance.&lt;/p&gt; &lt;p&gt;&lt;em&gt;Key words: Flight software, migration, birds, energetic parameters, prognosis, modeling.&lt;/em&gt;&lt;/p&gt;

The phylogenetic relationships of the extant pelicans inferred from DNA sequence data

The pelicans are a charismatic group of large water birds, whose evolutionary relationships have been long debated. Here we use DNA sequence data from both mitochondrial and nuclear genes to derive a robust phylogeny of all the extant species. Our data rejects the widespread notion that pelicans can be divided into white- and brown-plumaged groups. Instead, we find that, in contrast to all previous evolutionary hypotheses, the species fall into three well-supported clades: an Old World clade of the Dalmatian, Spot-billed, Pink-backed and Australian Pelicans, a New World clade of the American White, Brown and Peruvian Pelicans, and monospecific clade consisting solely of the Great White Pelican, weakly grouped with the Old World clade. We discuss possible evolutionary scenarios giving rise to this diversity.

Shifts in breeding phenology as a response to population size and climatic change: A comparison between short- and long-distance migrant species

ABSTRACT. Although changes in the mean arrival and breeding dates of some species are expected in response to climate change, other species may respond to direct or indirect climate effects by modifying the duration of their breeding period. We used a 20-year database for two closely related species that breed in sympatry in Europe, the short-distance migrant Dalmatian Pelican (Pelecanus crispus) and the long-distance migrant Great White Pelican (P. onocrotalus), to test for changes in breeding phenology over the past two decades. Median laying dates of the species covaried over time, indicating that the same or similar environmental factors probably influenced both species at their breeding sites. However, direct climate effects were revealed only for the short-distance migrant species, which showed a rapid advancement in its median laying dates (1.4 days year-1). This shift was associated with (1) an increase in population size and (2) weather variation following warmer and wetter winters. Earlier breed...

Systemwide Evaluation of Avian Predation on Juvenile Salmonids from the Columbia River Based on Recoveries of Passive Integrated Transponder Tags

AbstractWe recovered passive integrated transponder (PIT) tags from nine piscivorous waterbird colonies in the Columbia River basin to evaluate avian predation on Endangered Species Act (ESA)‐listed salmonid Oncorhynchus spp. populations during 2007–2010. Avian predation rates were calculated based on the percentage of PIT‐tagged juvenile salmonids that were detected as passing hydroelectric dams and subsequently were consumed and deposited by birds on their nesting colonies. Caspian terns Hydroprogne caspia (hereafter, “terns”) and double‐crested cormorants Phalacrocorax auritus (hereafter, “cormorants”) nesting on East Sand Island in the Columbia River estuary consumed the highest proportions of available PIT‐tagged salmonids, with minimum predation rates ranging from 2.5% for Willamette River spring Chinook salmon O. tshawytscha to 16.0% for Snake River steelhead O. mykiss. Estimated predation rates by terns, cormorants, gulls of two species (California gull Larus californicus and ring‐billed gull L. delawarensis), and American white pelicans Pelecanus erythrorhynchos nesting near the confluence of the Snake and Columbia rivers were also substantial; minimum predation rates ranged from 1.4% for Snake River fall Chinook salmon to 13.2% for upper Columbia River steelhead. Predation on ESA‐listed salmonids by gulls and American white pelicans were minor (&lt;2.0% per ESA‐listed salmonid population) relative to predation by terns and cormorants. Cumulative impacts were greater for Snake River and upper Columbia River salmonids than for salmonids originating closer to the estuary because upriver salmonids must migrate past more bird colonies to reach the ocean. Predation rates adjusted for colony size (per capita rates) were significantly higher for terns and cormorants nesting at inland colonies (upstream of Bonneville Dam) than for those nesting in the estuary, suggesting that inland colonies have a greater reliance on salmonids as a food source. Management actions to increase salmonid survival by reducing avian predation in the estuary could be offset if birds that disperse from the estuary relocate to inland nesting sites on or near the Columbia River.

Autumn migration of soaring birds through the Gebel El Zeit Important Bird Area (IBA), Egypt, threatened by wind farm projects

SummarySystematic bird observations were performed during autumn 2006 in the migration bottleneck area of Zeit Bay, Egypt (27.73°N, 33.51°E), situated on the coast of the Gulf of Suez, opposite southern Sinai. Owing to the strong northerly winds in that area, considerable pressure exists to construct wind farms. A total of 145,432 soaring birds, including 134,599 storks and 9,376 raptors over a period of 453.6 hours were observed between 20 August and 29 October by two teams working daily in two shifts. White Stork Ciconia ciconia and European Honey Buzzard Pernis apivorus were the most numerous species (91.4% and 5.7% respectively) of all soaring birds observed. As both species migrate early, relatively few birds were recorded passing through in October. A total of 57,179 soaring birds were observed within a range of 2.5 km from the observers, and of these 32,248 were flying at heights up to 200 m. Few individuals of the rapidly declining breeding populations of Egyptian Vulture Neophron percnotperus (‘Endangered’) and Lesser Kestrel Falco naumanni (‘Vulnerable’) passed (8 and 33 respectively). Pallid Harriers Circus macrourus (‘Near Threatened’) however, were more numerous (100) than at other migration sites along the East African-West Asian Flyway (Israel, southern tip of Sinai, Suez and Bab-el-Mandeb). Western Marsh Harrier Circus aeruginosus and Montagu’s Harrier Circus pygargus were also more numerous than at these sites. Some other large migrant species, observed at Suez, Bab el-Mandeb or in Israel, were seen only in small numbers or not at all at Zeit Bay in autumn. Among them, the Steppe Eagle Aquila nipalensis being the best known example of loop migration, entering Africa at Suez and Bab el-Mandeb, is for this reason not expected in autumn at Zeit Bay, while in spring it is a regular migrant. The number of Black Storks Ciconia nigra observed accounted for 4.8% of the flyway population, that of White Storks for 33.3%, Great White Pelicans Pelecanus onocrotalus for a further 3.5% and European Honey Buzzards for 0.8%. The extrapolation of the number of birds passing through the study area during the migration season, suggests that it was used by 92% of the White Stork, 12% of the Black Stork, 5% of the Great White Pelican, 4% of the European Honey Buzzard and 2% of the Pallid Harrier flyway populations in autumn 2006.

American White Pelicans Feeding on Large Fish in Lanigan Creek, Saskatchewan

American White Pelicans Feeding on Large Fish in Lanigan Creek, Saskatchewan

Infestations of Piagetiella titan (Menoponidae: Mallophaga) on juvenile white pelicans (Pelecanus nocrotalus, L.) in Urmia Lake National Park, northwest Iran.

Pelecaniformes are large water birds feeding by hunting fish and living usually in the sea and in fresh water. Ectoparasitic lice of the genus Piagetiella are interesting from an ecological standpoint as they are found in the pouches of pelicans. Unlike chewing lice, which live on the body surface of the host, P. titan lives in the oral cavity of white pelicans (Pelecanus nocrotalus, L.). This study aimed to determine the infestation of white pelicans with P. titan in Urmia Lake, Northwest Iran, between June and August from 2004 to 2006. Sixty-two juvenile white pelicans at three different age groups of < 1 (n = 8), 1-2 (n = 23) and 3-7 (n = 31) weeks were investigated and 59 birds were found infested with lice. A total of 1637 lice were collected from the oral cavity and body of the birds, with the number of lice ranging from one to 112 per bird. P. titan were identified according to the criteria described by Price (1970), including the number of setae in various parts of body, the structures of prosternal, mesosternal and metasternal plates, the structures of female and male genitalia, presence of two ventral stout subapical setae on tibia II-III and the number of the ctenidia on femur III. This report describes P. titan on pelicans for the first time from Iran.

Nutrient Utilization and Diet Preference of American White Pelicans Consuming Either a Mono- or Multi-Species Diet

Abstract. American White Pelicans (Pelecanus erythrorhynchos) are reported to consume large quantities of commercial catfish in Alabama, Arkansas, Louisiana and Mississippi, negatively impacting aquaculture production. If pelicans consume a single item diet, such as catfish, nutritional deficiencies may result. Therefore, effects of mono-and multi-species diets were examined to determine nutritional impacts on pelicans in addition to determining if preferences for certain fish species exist. Twelve American White Pelicans captured in northwest Mississippi were used for a seven day metabolism trial followed by a two day preference trial. In the metabolism trial, pelicans were assigned to one of three treatment diets (four birds/diet): catfish only, carp only, or both (50% catfish and 50% carp). Pelicans consuming only catfish metabolized less dry matter, organic matter and energy than those consuming only carp or both. Four pelicans were used to determine preference for carp or catfish. Pelicans ate more (...

Interactions Between Double-crested Cormorants and Other Ground-Nesting Species

Increasing populations of Double-crested Cormorants (Phalacrocorax auritus; hereafter cormorants) are of concern regarding the displacement of other species from breeding colonies, but little is known about such interactions. Agonistic interactions between ground-nesting cormorants and American White Pelicans (Pelecanus erythrorhynchos; hereafter pelicans) were investigated and compared to those involving cormorants and Herring Gulls (Larus argentatus). Also, a survey of cormorant eggs in nests of other ground-nesting species was conducted. Of 158 agonistic interactions between cormorants and pelicans, 83% were threat displays, 9% attempts to steal nest material and 8% involved some form of physical contact. Pelicans defended their nests less frequently and engaged in fewer physical contacts (8%) in colonies mixed with cormorants compared to areas with only pelicans (33%). Herring Gulls engaged in more physical contact (26%) with cormorants in a mixed colony than when nesting only with other gulls (4%). Cormorant eggs were found in 1–26% of Herring and Ring-billed Gull (L. delawarensis) nests searched in the Great Lakes, and 0.3% of Caspian Tern (Hydroprogne caspia) nests at one location. The results indicate cormorants routinely engage in agonistic interactions with other ground-nesting birds; however, the type and importance of interactions varies. Site- and species-specific evaluation of interactions involving cormorants and other birds is recommended before taking management steps to reduce nest site competition.

Vector Competence of the Stable Fly (Diptera: Muscidae) for West Nile Virus

In 2006-2007, stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), were suspected of being enzootic vectors of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) during a die-off of American white pelicans (Pelecanus erythrorhynchos Gmelin) (Pelecanidae) in Montana, USA. WNV-positive stable flies were observed feeding en masse on incapacitated, WNV-positive pelicans, arousing suspicions that the flies could have been involved in WNV transmission among pelicans, and perhaps to livestock and humans. We assessed biological transmission by infecting stable flies intrathoracically with WNV and testing them at 2-d intervals over 20 d. Infectious WNV was detected in fly bodies in decreasing amounts over time for only the first 6 d postinfection, an indication that WNV did not replicate within fly tissues and that stable flies cannot biologically transmit WNV. We assessed mechanical transmission using a novel technique. Specifically, we fed WNV-infected blood to individual flies by using a cotton swab (i.e., artificial donor), and at intervals of 1 min-24 h, we allowed flies to refeed on a different swab saturated with WNV-negative blood (i.e., artificial recipient). Flies mechanically transmitted viable WNV from donor to recipient swabs for up to 6 h postinfection, with the majority of the transmission events occurring within the first hour. Flies mechanically transmitted WNV RNA to recipient swabs for up to 24 h, mostly within the first 6 h. Given its predilection to feed multiple times when disturbed, these findings support the possibility that the stable fly could mechanically transmit WNV.

Panmixia on a continental scale in a widely distributed colonial waterbird

Many highly mobile species, such as migratory birds, can move and disperse over long distances, yet exhibit high levels of population genetic structuring. Although movement capabilities may enable dispersal, gene flow may be restricted by behavioural constraints such as philopatry. In the present study, we examined patterns of genetic differentiation across the range of a highly mobile, colonial waterbird. American white pelicans (Pelecanus erythrorhynchos) breed across continental North America and are currently experiencing a range expansion, especially on the eastern range limit. To assess patterns of genetic structuring, we sampled 333 individuals from 19 colonies across their North American range. The use of ten variable microsatellite markers revealed high levels of allelic richness with no population differentiation. Both Bayesian and frequentist approaches to examining genetic structuring revealed a single panmictic population. We found no evidence of genetic structuring across the Continental Divide or between migratory and non-migratory colonies. The lack of any genetic structure across the range indicates that, unlike other waterbirds with similar life-history characteristics, extensive gene flow and presumably low philopatry appear to preclude genetic differentiation. The lack of population genetic structure in American white pelicans provides an example of range-wide panmixia, a rare phenomenon in any terrestrial species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 583‐592.

Diversity of the Cuticle Layer of Avian Eggshells

The structure and mineral composition of eggshell cuticles were studied in 5 species of birds. The approximate thickness of the cuticle layer at the top of shell columns was about 1μm in the Red Junglefowl (Gallus gallus), about 130μm in the White Pelican (Pelecanus onocrotalus), about 10μm in the Japanese quail (Coturnix japonica), about 110μm in the Greater Flamingo (Phoenicopterus ruber roseus) and about 45μm in the Humboldt Penguin (Spheniscus humboldti). The matrix of the cuticle layer decalcified with EDTA was composed of vesicles in a variety of sizes in all birds. Major elements in cuticle materials detected by X-ray microanalysis were O, C, Ca and P, and their percentage numbers of atoms decreased in this order. The concentration of P was significantly higher in the cuticles of the quail, flamingo, and penguin than in those of the junglefowl and pelican. Ca mapping on electron-microscopic images showed strong signals in the shell layer and weaker ones in the cuticle layer, whereas P mapping showed that signals were mostly confined in the cuticle layer. X-ray diffraction analyses on the inside of the shell layer showed a profile of calcite crystals of calcium carbonates in all birds. In the cuticle materials, the profile was of calcite in the junglefowl, and a mixture of calcite and vaterite in the pelican. The profiles in cuticle materials of the quail, flamingo and penguin showed no specific signals, indicating that mineral compounds are amorphous in these forms. It was suggested that the diversity of mineral structures in the cuticle layer is caused by the presence of phosphorous, in addition to the structure of the cuticle matrix.

Mitochondrial Evidence for Panmixia despite Perceived Barriers to Gene Flow in a Widely Distributed Waterbird

We examined the mitochondrial genetic structure of American white pelicans (Pelecanus erythrorhynchos) to: 1) verify or refute whether American white pelicans are panmictic and 2) understand if any lack of genetic structure is the result of contemporary processes or historical phenomena. Sequence analysis of mitochondrial DNA control region haplotypes of 367 individuals from 19 colonies located across their North American range revealed a lack of population genetic or phylogeographic structure. This lack of structure was unexpected because: 1) Major geographic barriers such as the North American Continental Divide are thought to limit dispersal; 2) Differences in migratory behavior are expected to promote population differentiation; and 3) Many widespread North American migratory bird species show historic patterns of differentiation resulting from having inhabited multiple glacial refugia. Further, high haplotype diversity and many rare haplotypes are maintained across the species' distribution, despite frequent local extinctions and recolonizations that are expected to decrease diversity. Our findings suggest that American white pelicans have a high effective population size and low natal philopatry. We suggest that the rangewide panmixia we observed in American white pelicans is due to high historical and contemporary gene flow, enabled by high mobility and a lack of effective physical or behavioral barriers.