Trends in North American vulture populations

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

منو

" Trends in North American vulture populations "
Avery, Michael L.

Document Type	:	AL
Record Number	:	943416
Doc. No	:	LA66q02691
Language of Document	:	English
Main Entry	:	Avery, Michael L.
Title & Author	:	Trends in North American vulture populations [Article]\ Avery, Michael L.
Title of Periodical	:	Proceedings of the Vertebrate Pest Conference
Volume/ Issue Number	:	21
Date	:	2004
Abstract	:	In recent years, interactions between vultures and human activities have noticeably increased. These interactions include nuisance roosts, damage to homes and businesses, livestock depredation, and collisions with aircraft. One major factor contributing to the upsurge in vulture problems is higher numbers of these birds. Both turkey vultures and black vultures appear to be experiencing major population increases throughout much of their ranges in the United States. During 1990-2002, Christmas Bird Count (CBC) data revealed annual nationwide increases of 1.79% and 5.97% for turkey vultures and black vultures, respectively. Estimates from Breeding Bird Survey (BBS) data were 1.99% and 4.97% for the two species. Despite substantial differences in methodology associated with these two sets of data, they are consistent in charting overall increases in populations of both vulture species. Positive population trends are mostly confined to the eastern half of the country. The usefulness of survey data like the CBC and BBS is currently being seriously questioned, but for vultures I contend that the objections to the survey data are not critical. Nevertheless, suggestions for improved data collection procedures are offered.