American white pelicans breeding in the northern plains: productivity, behavior, movements, and migration (original) (raw)
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Historic and Current Status of the American White Pelican Breeding in California
Waterbirds, 2005
Chase Lake National Wildlife Refuge currently supports the largest breeding colony of the American White Pelican ( Pelecanus erythrorhynchos ) in North America. The first written account of the colony's status was in 1905, when approximately 500 pelicans nested on two islands in Chase Lake. The colony grew to nearly 34,000 breeding birds by 2002. Surveys of breeding pelicans in the colony were sporadic from 1905 until 1972. Because the availability of foraging areas affects recruitment, pond counts from south-central North Dakota were used as an index of the relative availability of foraging areas. Pond counts varied widely in the 1970s and 1980s. In 1993, pond numbers increased dramatically, reached a peak in 1997, then declined but remained relatively high through 2002. Pelican numbers also increased in the mid-to late-1990s, possibly in response to increased and stable foraging opportunities. Because rising water in Chase Lake inundated the original nesting islands during that period, pelicans were forced to relocate nesting areas. Relocation provided more nesting space than the original islands, and nesting pelicans seemed to be gradually filling these areas. Threats to the Chase Lake breeding colony include disease, predation, and human disturbance. Research is needed to better understand the mechanisms that underlie the dynamics of AWPE metapopulations and their sub-units, including factors that influence nest-site selection, productivity, and survival of adults and young in large colonies.
Introduction: Biology and Conservation of the American White Pelican
Waterbirds, 2005
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 "evolutionarily significant units" for American White Pelican conservation, (2) to study movements and genetic exchange among and between these divisions, and to study movement patterns and genetic mixing among these divisions during long-and short-term changes in environmental conditions.
Waterbirds, 2005
Chase Lake National Wildlife Refuge currently supports the largest breeding colony of the American White Pelican ( Pelecanus erythrorhynchos ) in North America. The first written account of the colony's status was in 1905, when approximately 500 pelicans nested on two islands in Chase Lake. The colony grew to nearly 34,000 breeding birds by 2002. Surveys of breeding pelicans in the colony were sporadic from 1905 until 1972. Because the availability of foraging areas affects recruitment, pond counts from south-central North Dakota were used as an index of the relative availability of foraging areas. Pond counts varied widely in the 1970s and 1980s. In 1993, pond numbers increased dramatically, reached a peak in 1997, then declined but remained relatively high through 2002. Pelican numbers also increased in the mid-to late-1990s, possibly in response to increased and stable foraging opportunities. Because rising water in Chase Lake inundated the original nesting islands during that period, pelicans were forced to relocate nesting areas. Relocation provided more nesting space than the original islands, and nesting pelicans seemed to be gradually filling these areas. Threats to the Chase Lake breeding colony include disease, predation, and human disturbance. Research is needed to better understand the mechanisms that underlie the dynamics of AWPE metapopulations and their sub-units, including factors that influence nest-site selection, productivity, and survival of adults and young in large colonies.
Waterbirds
Satellite telemetry was used to investigate summer and winter home ranges for resident and migrant American White Pelicans (Pelecanus erythrorhynchos) captured in the southeastern United States between 2002 and 2007. Home range utilization distributions were calculated using 50% and 95% kernel density estimators with the plug-in bandwidth selector. Mean summer home ranges (95%) varied from 177 to 4,710 km 2 and mean winter home ranges (95%) ranged from 185 to 916 km 2. Mean 50% and 95% home ranges of adult American White Pelicans during summer tended to be larger than those during winter, whereas mean 50% and 95% home ranges of immature pelicans during summer tended to be smaller than those during winter. Home ranges for all American White Pelicans encompassed the latitude range of 24°-55° N, including wintering, stop over, and nesting habitat. These data provide baseline movement and home range data for future studies of American White Pelican ecology.
Status of a Northern Population of California Brown Pelicans
The Condor, 1983
In the Southern California Bight (SCB), Brown Pelican (P&anus occidentalis californicus) breeding populations were apparently historically stable. They are again increasing after pollution-related declines in the late 1960' s and early 1970' s. This increase has been bolstered by recruitment into the breeding population of pelicans fledged outside the SCB area, but populations did not increase significantly until after improvements in reproduction of the SCB population itself. Nesting chronology is apparently related to food availability. Earlynesting, whether at Anacapa Island or Islas Los Coronados, usually confers a reproductive advantage. This advantage varies at each location; breeding populations reassort each year, apparently in response to variable food supplies. Shifting between two major breeding colonies in the SCB is apparently a response to a changing food supply distribution. Annual variations in normal (as opposed to pollution-affected) breeding population size result partly from changing proportions of the available adult population that actually breeds.