Status of breeding colonies of white pelicans Pelecanus erythrorhynchos, in the U.S.A. through 1979.




Sloan, N.F.

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The 1979 survey of white pelicans in the USA indicated that the overall population was down slightly. When an examination is made of population on a state-by-state basis some definite changes in population levels can be seen. California appeared to have a large increase in population, but it may not be a real increase; some birds may have been counted twice. The 1963-1964 population figures represent a different nesting population from the 1971-1972 and 1979 surveys. But between these last two surveys, a group of refuges in California and Oregon were united under a single management unit, the Klamath Basin National Wildlife Refuge. Birds counted in Oregon in 1963 were now included in the California figure. No work is currently being conducted on the colony of Pelican-Crump Lake in Oregon, so no data are available on the population there. Montana is having serious problems with its pelicans. There, numbers have dropped from a high of 10107 in 1953-1964 to 3500 in 1979. Much of this loss was from water level fluctuation. Nevada also experienced a similar population decline going from 6500-3600. Other colonies showed either a constant level or increased, as did those in Utah, Wyoming, Colorado, and South Dakota. The Chase Lake colony, the largest in the USA, appeared to be dispersing. Its population declined from a high of 10000 to approximately 8000. Some of the Chase Lake birds moved to Minnesota and established new colonies there. Minnesota had no breeding birds in 1963-1964 and now in 1979 had approximately 1000. Color-banded birds from Chase Lake have been seen nesting in the Minnesota colonies. Several 3 year old pelicans were seen incubating. In addition to the sightings in Minnesota, 9 color marked pelicans were reported at Pelican Island, Lake Newell in Alberta, Canada during the summer of 1978 and 1979. Breeding-age birds left the Chase Lake area and established new colonies in other locations. The population of non- migratory pelicans in Texas had decreased significantly from a high of 1750 in the 1960's to only 200 in 1979. Overall figures indicated the white pelican population in the USA may be down from previous surveys. The white pelican should be considered threatened under the Federal Endangered Species program so that funds would be available to have a nationwide study to examine each colony and determine what is limiting the colony or what factors are allowing others to increase. Reproductive success is definitely better at the smaller nesting locations than at the large colonies. Perhaps an attempt should be made to colonize from some of the larger colonies and establish colonies at new locations. The white pelican is currently on the Blue List of American Birds as a species of special concern (Tate and Tate 1982), and should continue on that listing of potential problem species.


p. 250-254.


ornithology, white pelican, Pelecanus erythrorhynchos, population dynamics, reproduction