Pelecanus Erythrorhynchos Research Articles

Contaminant Levels in Eggs of American White Pelicans, <em>Pelecanus erythrorhynchos</em>, from Chase Lake, North Dakota

American White Pelicans (Pelecanus erythrorhynchos) are colonial nesters, making them susceptible to site-specific mortality factors. One of the largest known breeding colonies is at Chase Lake National Wildlife Refuge in North Dakota. In 2004, this colony suffered total reproductive failure. In 2005, we collected abandoned eggs from this colony to test for environmental contaminants. Nine eggs were analyzed for 28 organochlorine pesticides, total polychlorinated biphenyls, and 26 inorganic elements. Based on concentrations in this sample of eggs and levels linked to reproductive problems in birds, adult pelicans in the Chase Lake breeding colony are not at known risk from any of the environmental contaminants we measured.

Development and characterization of microsatellite loci from the Great White Pelican (Pelecanus onocrotalus) and widespread application to other members of the Pelecanidae

We describe the isolation of 10 microsatellite loci from the Great White Pelican using an enrichment protocol. All loci were variable with the number of alleles ranging from 2 to 19, and observed heterozygosity ranging from 0.261 to 0.913. Two loci were out of Hardy–Weinberg equilibrium, although in each case this was restricted to one of the two populations screened. None of the loci were linked. Eight to 10 loci PCR-amplified in three related species: Brown, American White and Pink-backed Pelicans. These loci should prove to be widely applicable to studies of phylogeography and demography in pelicans globally.

Feeding frequency influences crèching age in the Dalmatian pelican, Pelecanus crispus

Creching behaviour is common in colonial seabirds; nevertheless, the factors inducing chicks to aggregate remain relatively poorly understood. It has been proposed that brood size, laying date and nest attendance are important factors in the formation of a creche. Moreover, in most species of pelicans, chicks join creches following the development of homoeothermy and coincident with the end of the brooding behaviour. We studied effects of feeding rate, nest attendance, brood size, laying date and homoeothermy on the age at which chicks entered the creche at a colony of Dalmatian pelicans (Pelecanus crispus), in Srebarna, Bulgaria. Single chicks were fed more frequently than chicks from two-chick broods. Unlike American white pelicans (Pelecanus erythrorhynchos), Dalmatian pelicans maintained brooding behaviour a further 9 days after chicks had developed thermoregulation abilities. In contrast to nests with two chicks, nests with only one chick were never left unattended by the parents before the chick reached the creching stage. Laying date, nest attendance and brood size did not affect the age that the chick entered the creche. The age the chick entered the creche was not correlated with the age of homoeothermy acquisition, but chicks significantly joined the creche at younger ages when the mean number of feeds per chick per day during the rearing period in the nest was higher. This result suggests an implication of growth rate in the creching age. Joining the creche earlier can provide benefits that could have strong implications for the chicks’ future reproductive lives.

Impact of West Nile virus and other mortality factors on American white pelicans at breeding colonies in the northern plains of North America

American white pelicans (Pelecanus erythrorhynchos) are colonial-nesting birds and their breeding sites are concentrated in a few small areas, making this species especially vulnerable to factors that can influence productivity, such as disease, disturbance, predation, weather events and loss of nesting habitat. Nearly half of the American white pelican population breeds at four colonies in the northern plains: Chase Lake National Wildlife Refuge (NWR) in North Dakota, Bitter Lake (Waubay NWR) in South Dakota, Medicine Lake NWR in Montana, and Marsh Lake in Minnesota. Thus, sustained productivity at these colonies is crucial to the health of the entire species. During the latter half of the 2002 and 2003 breeding seasons, unusually high mortality of pelican chicks was observed at these colonies. West Nile virus (WNv) was identified as one source of these losses. In 2004–2007 we monitored three major colonies in the northern plains to assess mortality of chicks during the late breeding season. We documented severe weather events, disturbance, and WNv as factors contributing to chick mortality. Before WNv arrived in the region in 2002, chick mortality after mid-July was ⩽4%, and then jumped to as high as 44% in the years since WNv arrived. WNv kills older chicks that are no longer vulnerable to other common mortality factors (e.g., severe weather, gull predation) and typically would have survived to fledge; thus WNv appears to be an additive mortality factor. Persistence of lower productivity at American white pelican colonies in the northern plains might reduce the adult breeding population of this species in the region.

VISITS TO WHITE PELICAN NEST COLONIES AT NIGHT REDUCE RESEARCHER IMPACTS ON NESTING SUCCESS

Reproductive success of American White Pelicans (Pelecanus erythrorhynchos) was monitored at a nesting colony on Anaho Island, Pyramid Lake, Nevada in 1996 as part of an environmental contaminants study. Reproductive success was normal based on hatching rates of eggs (≥ 75% in undisturbed areas) and survival of nestlings. We entered 2 subcolonies after dark to reduce impacts of our egg collecting activities. Human disturbance from egg collection activities did not result in reduced production at one subcolony, where 80% of eggs in both sampled and unsampled nests resulted in 2-wk-old young. However, in a second subcolony only 60% of eggs in sampled nests and 30% in unsampled nests resulted in 2-wk-old young. Data from this study suggests colony visits for sample collection be done at night rather than the day to preclude gull predation and reduce heat stress on eggs and nestlings.

American White Pelicans Force Copulations with Nestlings

We observed 56 forced copulation (FC) events in a breeding colony of American White Pelicans (Pelecanus erythrorhynchos) in Saskatchewan, Canada during the 2005 nesting season. All FCs were directed at nestlings >21 days of age that were not continuously attended by an adult. The onset of FCs occurred in close synchrony with an unexpected late-season increase in adult copulation attempts. We suggest that FC directed at nestlings is not simply an aberrant and non-adaptive behavior. Rather, copulations with nestlings result from adult male pelicans being inappropriately stimulated to copulate with nestlings when actually seeking copulations with adult females.

Mercury and Selenium in American White Pelicans Breeding at Pyramid Lake, Nevada

Abstract American White Pelicans (Pelecanus erythrorhynchos) that breed on Anaho Island, Pyramid Lake, Nevada, are potentially exposed to a variety of contaminants. Therefore, the reproductive success of this colony was monitored in 1996 and eggs, blood and feathers from nestlings, livers from adults and nestlings, regurgitated fish from nestlings, and fish from representative feeding areas were collected and analyzed for mercury and selenium to determine exposure to the pelicans and sources of contamination. Additional samples were collected and analyzed in 1988, 1992, and 2004. Reproductive success at the Anaho Island colony was normal in 1996 based on hatching rates of eggs (≥75% in undisturbed areas) and survival of nestlings. Mercury and selenium concentrations in eggs were generally below known effect levels and did not appear to have an adverse impact on hatching success. Mercury and selenium concentrations in fish ranged widely, with mercury of greatest concern. Microscopic lesions characteristic ...

A nondamaging blood sampling technique for waterfowl embryos

Development of minimally invasive techniques to collect blood in free-living birds is desirable for both ethical and conservation reasons. We describe a new, simple technique for collecting blood samples from waterfowl eggs that involves recovering blood from a small hemorrhage after puncturing the shell of eggs showing the first signs of hatching. This technique allowed us to obtain a large number of blood samples from hatchling Greater Snow Geese (Chen caerulescens atlantica) and did not require the sacrifice or retention of any individuals, thus minimizing stress. High-quality blood samples for genetic studies were obtained, with no adverse effects on either embryos or the post-hatch survival of young geese. SINOPSIS. Una nueva t´ ecnica para obtener muestras de sangre de embriones de gansos Esy deseable, en aras de conservar, el desarrollar tpoco invasivas para tomar muestras de sangre de aves vivas. Describimos una tpara tomar muestras de sangre de huevos de gansos que consiste en tomar sangre de la pequehemorragia producida por una puncidel cascaron cuando se observan lo primeros signos de eclosionar. Este tpermiti´ o tomar una muestra considerable de sangre de huevos de ganso (Chen caerulescens atlantica) sin requerir sacrificar o retener a ning´ un individuo, minimizando de esta forma el estrcausando por lo ´ ultimo. Las muestras tomadas fueron de alta calidad para angensin que se observara efecto adverso alguno en los embriones o la supervivencia de los gansitos producto de los huevos manipulados y que eclosionaron.

HABITAT PREFERENCES OF SURFACE-DIVING WATERBIRDS AND AMERICAN WHITE PELICANS WINTERING IN REDFISH BAY, TEXAS

Habitat preferences were determined for a guild of surface-diving waterbirds wintering in Redfish Bay, Texas: common loon (Gavia immer), eared grebe (Podiceps nigricollis), pied-billed grebe (Podilymbus podiceps), double-crested cormorant (Phalacrocorax auritus), red-breasted merganser (Mergus serrator), and American coot (Fulica americana). American white pelican (Pelecanus erythrorhynchos) also was included because it occupies habitats similar to those of the surface divers. Between November 2001 and April 2002, the locations of 4,232 surface divers and American white pelicans using aquatic habitats in Redfish Bay were recorded and entered into a GIS that included a National Wetlands Inventory layer. Bird habitat preferences-avoidances were determined using a test based on Bonferroni's inequality. American coots, American white pelicans, and pied-billed grebes preferred shallower estuarine subtidal seagrass beds, whereas common loons, double-crested cormorants, and eared grebes preferred deeper estuarine subtidal unconsolidated bay bottom. Red-breasted mergansers showed no habitat preferences.

History and Breeding Ecology of the American White Pelican at Medicine Lake National Wildlife Refuge, Montana

The American White Pelican (Pelecanus erythrorhynchos) has been breeding at Medicine Lake National Wildlife Refuge (NWR) in northeastern Montana since 1939. We compiled information on the history and ecology of this breeding colony from U.S. Fish and Wildlife Service (USFWS) reports and narratives filed at Medicine Lake NWR. Nesting by American White Pelicans first occurred in 1939, and the recent 10-yr average size (1993-2002) is about 4,000 breeding pairs. Since 1990, the mean number of young fledged pair-1 was 0.51 ± 0.07 (SE, N = 56). Low temperatures, hailstorms, predation, and botulism have killed >50% of young pelicans in some years. American White Pelicans banded at Medicine Lake migrated south, mostly within the Central Flyway. They wintered predominately in Texas, Louisiana and Mexico. Protection of the Medicine Lake colony is important because the breeding colony is the largest in Montana and an important contributor to the eastern metapopulation.

An Overview of the American White Pelican

Comments on the American White Pelican (Pelecanus erythrorhynchos) in North America languished until Peter Ogden reported trapping one during his 1825 expedition to Utah. Brief accounts of the American White Pelican by ornithologists continued through the 1940s. In subsequent decades, scientific studies uncovered greater details of the species' biology and natural history, although documenting numbers has been difficult and tentative. Estimates of numbers of adults began at 30,000 in 1933, increased to over 100,000 by 1985, and by 1995 the total number of birds, then also including non-breeders, was estimated to be around 400,000. Beginning in the 1880s, their feeding and nesting sites were degraded by engineered water diversions and drainage of wetlands for agriculture. At the same time, pelicans were shot and clubbed, and eggs and young were intentionally destroyed largely because the birds were thought to compete with humans for fish. After the 1960s, hundreds of pelicans died yearly due to the ingestion of insecticides such as toxaphene, endrin, and dieldrin. As recently as winter 1998-99, 800 American White Pelicans died in Florida from poisoning by insecticides that were resuspended from flooded agricultural soils. In 1996 a disease pandemic at Salton Sea, California, killed over 7,500 pelicans in just several months. American White Pelicans have adapted to much persecution by simply moving. Overall, I do not believe that unusual mortalities have threatened their abundance.

The Impact of Disease in the American White Pelican in North America

Abstract Records of reported die-offs of the American White Pelican (Pelicanus erythrorhynchos) held by the U.S. Geological Survey National Wildlife Health Center from 1978 through 2003 indicate that type C botulism (caused by Clostridium botulinum) was the major cause of mortality. In 1996, over 15,000 birds, including 8,500 American White Pelicans, were estimated to have died from type C botulism at the Salton Sea in California. This was the largest documented die-off of any pelican species and was estimated to represent 15-20% of the western metapopulation. This event was also notable in that it was the first time that fish, specifically Tilapia (Oreochromis mossambicus), were implicated as the source of type C botulinum toxin for birds. Type C botulism has recurred in both North American species of pelicans at the Salton Sea every year since, although the magnitude of mortality is much lower. West Nile virus caused mortality in both adult and immature American White Pelicans, but may have a more signi...

Interactions Between the American White Pelican and Aquaculture in the Southeastern United States: an Overview

Abstract The eastern metapopulation of the American White Pelican (Pelecanus erythrorhynchos) breeds mainly in the Northern Great Plains, migrates through the Great Plains and along the Mississippi River and winters in the lower Mississippi River Valley and along the Gulf of Mexico. The production of farm-raised Channel Catfish (Ictalurus punctatus) in the southeastern United States has increased dramatically in the last 25 years. In 1990, U.S. Department of Agriculture Wildlife Services offices in Arkansas, Louisiana and Mississippi began receiving complaints concerning the foraging of pelicans in commercial Channel Catfish ponds. Because of the relatively shallow depth and high fish-stocking rates used by most catfish producers, these ponds provide an ideal foraging environment for the American White Pelican. Although the impact of foraging pelicans can be economically significant, the potential for pelicans to transmit trematode infections and other diseases to aquaculture facilities can be more destru...

The Use of Culmen Length to Determine Sex of the American White Pelican

Culmen length has been suggested as being diagnostic for sex in the American White Pelicans (Pelecanus erythrorhynchos). However, the literature on the use of culmen length to determine sex is inconsistent, with reported overlap in culmen lengths for males and females ranging from 1 mm to >120 mm. Morphological measurements from 188 American White Pelicans collected in Mississippi and Louisiana whose sex was determined by dissection and gonadal inspection were measured. The use of culmen length alone was used to determine gender for this sample by establishing the minimum observed culmen length for males and the maximum observed culmen length for females that provided the fewest incorrect determinations for each gender. A multivariate discriminant function model was developed to determine sex from our data and compared the diagnostic accuracy of the model with the accuracy based on culmen length alone. Both methods were validated using an independently collected sample of 22 pelicans from Florida. A culmen length of ≥310 mm for males and ≤309 mm for females from our data correctly classified sex for 99% of American White Pelicans from our Mississippi and Louisiana samples and 95% of AWPE for the Florida sample. Culmen length and wingcord length were significant variables in the discriminant function model. The resulting model correctly classified sex of 97% of the birds and 94% of the independent Florida sample. The culmen length alone predicted the sex of American White Pelicans as well as multivariate methods and provides an accurate simple, non-lethal method for sexing the species.

Historic and Current Status of the American White Pelican Breeding in California

The American White Pelican (Pelecanus erythrorhynchos) formerly bred the length of California on interior lakes and marshes of the Klamath Basin, Modoc Plateau and Great Basin desert of northeastern California, overflow lands of the Sacramento Valley, terminal lakes in the Tulare Basin of the San Joaquin Valley and at the Salton Sea in the Colorado desert. Historic data are sketchy but nesting is well documented for at least eleven sites. Though unknown, the number of pelicans breeding in the late 1800s and early 1900s may have exceeded 20,000 pairs. Decades of declining numbers and range retraction have left the American White Pelican breeding regularly in California at only two sites in the Klamath Basin (Sheepy Lake on Lower Klamath National Wildlife Refuge and Clear Lake National Wildlife Refuge), where very vulnerable to catastrophic losses. Variably obtained counts at these two sites combined appeared to decrease from about 4,500 nests in 1912 to reach an equilibrium, which fluctuated around 1,600-1,700 nests from the 1950s to present. Annual variation is presumably a response in part to prey availability mediated by water levels. Several high nest counts of 2,300-2,500 at Clear Lake since the early 1970s may partly reflect greater accuracy from aerial photo counts. Declines were caused by shooting, human disturbance and, particularly, habitat loss from water diversions and land reclamation for agriculture. The American White Pelican is currently limited in California by the availability of remote, undisturbed nesting sites and rich foraging habitats. Contaminant effects on breeding pelicans have lessened, but large numbers of pelicans have recently died from type C avian botulism outbreaks at the Salton Sea. Management and research should serve the protection and enhancement of breeding conditions in the Klamath Basin.

Biology and Conservation of the American White Pelican: Current Status and Future Challenges

Abstract The goals of this symposium were to foster exchange of information and to identify priorities for future research. The workshop, oral presentations, and poster session that comprised the symposium provided a broad overview of our knowledge of the biology and present status of the American White Pelican. Here, the workshop, the contributed papers at the symposium, and articles in this volume are summarized as they relate to the goals of the symposium.

Fifty Years of American White Pelican Breeding at Stum Lake, British Columbia

Abstract The only breeding colony of the American White Pelican (Pelecanus erythrorhynchos) in British Columbia is located at Stum Lake. The species in British Columbia. is designated “Endangered” and it is also included on the provincial “Red List.” As such, the Stum Lake colony has been monitored regularly since 1994, and older records of nest counts and pre-fledgling numbers date back as far as 1953. A marking program for pre-fledging American White Pelicans was conducted from 1968 to 1993. During recent surveys, censuses of nest depressions were obtained late in the breeding season; pre-fledged young were also enumerated. Based on nest counts, numbers at Stum Lake declined in the 1960s and remained more or less stationary throughout the 1970s and early 1980s. In the late 1980s and early 1990s, the number of nesting pairs increased dramatically; and in the past decade, numbers of breeding birds at Stum Lake has stabilized at the highest since monitoring began (1953). The mean number of pre-fledged youn...

Introduction: Biology and Conservation of the American White Pelican

Abstract Two separate, large-scale management units for the American White Pelican (Pelecanus erythrorhynchos) in North America are proposed: the eastern and western metapopulations, separated by the North American Continental Divide. The populations on either side of this barrier are subject to contrasting ecological conditions, movement patterns suggest strong geographic separation and each is likely demographically distinct. Subdivisions within these demographic units need to be more precisely defined in the future. Yet, because of the highly colonial nesting habits of the American White Pelican, conservation can still be effective if directed toward separate breeding colonies. Our intent is to provide a compilation of current knowledge regarding species status, distribution and ecology. Herein, further study is recommended: (1) to determine genetic characteristics and the degree of genetic separation of the various geographic divisions in the range of the species to help ultimately better define “evol...

Century-long Impacts of Increasing Human Water Use on Numbers and Production of the American White Pelican at Pyramid Lake, Nevada

Anaho Island, Pyramid Lake, Nevada supports the largest colony of the American White Pelican (Pelecanus erythrorhynchos) in western North America. Counts of adults, nests and chicks, from 1903 to the present, are positively correlated with flow volumes of the Truckee River in spring near Nixon, Nevada, 15 km from the lake. Upriver diversions of water have markedly reduced flows of the lower Truckee River and have likely depressed pelican production; for example, the Derby Dam, completed in 1906, diverts water from the Truckee River into the Truckee Canal and out of the Truckee River basin. American White Pelican production was negatively correlated with flows in the Truckee Canal. If water had remained in the river instead of being diverted, it is estimated that annual colony production would have averaged 8% higher. A more complete model, accounting for seasonal diversions of water from the river between the gage upriver at Farad and the gage near Nixon, predicted that colony production would have averaged as much as 58% higher if natural flow regimes had persisted in the Truckee River downriver from Farad. Human removals of water from the Truckee River, and thus simulated reductions on pelican colony production, were highest in drought years. Despite the likely reductions in production throughout the last century, particularly in drought years, numbers of adults and nests at this breeding colony demonstrated no long-term directional trends. Therefore, reductions in production apparently have been offset by higher survival or immigration from other colonies. Even so, higher production could be an important buffer against high mortality events, such as the disease die-offs of large numbers of American White Pelicans at Salton Sea, California, and even natural disasters described by other authors in this symposium.

Organochlorine Contaminants in the American White Pelican Breeding at Pyramid Lake, Nevada

Abstract Reproductive success of the American White Pelican (Pelecanus erythrorhynchos) was monitored at a breeding colony on Anaho Island, Pyramid Lake, Nevada in 1996. Eggs were collected in 1988 and 1996 and analyzed for organochlorine pesticides (OCs) and total polychlorinated biphenyls (PCBs). Muscle from adults found dead or debilitated and euthanized, fishes from representative feeding areas and regurgitated fish samples from nestlings were also analyzed for OCs and PCBs. Reproductive success at the breeding colony was normal in 1996 based on hatching rates of eggs (≥79% in undisturbed areas) and survival of nestlings. Organochlorine pesticide and PCB concentrations in eggs were below known effect levels on reproduction. DDE concentrations in eggs from Anaho Island declined between 1988 and 1996. Eggshell thickness for the Anaho colony was significantly lower (6%) than the pre-OC norm, but the level of thinning was less than that associated with population declines. OCs and PCBs were seldom detecte...