Raptor Population Index







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  Assessments:

Species Assessment:
Osprey (Pandion haliaetus)

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The 10-year migration count trends for Osprey suggest mostly stable numbers across North America with 64% of sites showing stable counts and 28% showing a decline. In the East, patterns are similar with 59% of sites showing stable counts in the last decade and 36% declining. Most of the Gulf sites reported stable counts, whereas 33% of Central Region sites had increasing trends and 100% if the West Region sites were stable (see pie charts and trend maps below). Declines during the past decade seem clustered in the Eastern Great Lakes and Appalachians and not along the Atlantic Coast or farther west. Twenty-year count trends (not shown) similarly show mixed trends varying among regions (East Region: 15 stable, 1 increase, 7 decrease; Central Region: 2 decrease; west region: 5 stable; Gulf Region: 2 stable, 1 increase, 2 decrease). Although the highest average counts occur at coastal sites such as Cape May, New Jersey, with 3,695 Osprey per year, notable declines have occurred at sites such as Quaker Ridge, Connecticut, averaging 525 osprey per year with a 3.3% per year decline in the recent decade. Some researchers suggest the increasing population of Bald Eagles at inland lakes may be limiting nesting sites for Osprey in inland lakes. Along coastlines, Osprey often cluster in colonies and maybe better able to stave off competition and predation by Bald Eagles. More research is needed to understand the reasons for the observed declines.

Winter survey data from the Christmas Bird Count (CBC) only records data on Osprey in southern coastal states from Carolinas to Florida and west to Texas and to California, Oregon, Washington. The trends for wintering Osprey show mostly increasing or stable 10-year trends for these coastal populations, except in Washington where declines are noted. The Osprey is listed as a species of Least Concern throughout its range by the IUCN Red List, but it is vulnerable to threats such as loss of habitat, increasing competition with bald eagles, bioaccumulation of heavy metals and contaminants, collisions, and entanglement.

Osprey<br>Photo by Bill Moses

Photo by Bill Moses







Please cite this page as:
    D. Oleyar, D. Ethier, L. Goodrich, D. Brandes, R. Smith, J. Brown, and J. Sodergren. 2021. The Raptor Population Index: 2019 Analyses and Assessments.