American Peregrine Falcon Monitoring Along the Upper Yukon River, Yukon-Charley Rivers, Alaska, 2005

Guldager, Nikki; Ambrose, Skip; Florian, Chris

American peregrine falcons along the upper Yukon River, Alaska, have been monitored almost continuously since 1973. This and other local populations in interior Alaska have increased steadily since the late 1970s, following the ban of DDT in the United States in 1972, and their listing as endangered in 1973 under the Endangered Species Act. In August 1999, the American peregrine falcon was removed from the list of Threatened and Endangered Wildlife. Section 4(g)(1) of the Endangered Species Act requires that all species which have recovered and have been removed from the list are monitored for not less than five years following delisting. 2004 was the last year of this five-year monitoring program initiated by the Air Force, U.S. Fish and Wildlife Service, and National Park Service. In 2003, the upper Yukon River peregrine falcon population was identified as one of two index populations in Alaska for long-term monitoring beyond 2004 (USFWS 2003), and in 2005 by the Central Alaska Network (as part of the NPS Vital Signs Inventory and Monitoring Program) as an important vital sign in determining ecosystem health (MacCluskie and Oakley 2005). A monitoring protocol was prepared (Ambrose et al. 2005) following standards of Oakley et al. (2003), which is currently in the peer review process. In 2005, 265 kilometers of the upper Yukon River were surveyed. Fifty nesting territories were occupied by American peregrine falcons (48 pairs and 2 single adults on territory). Thirty-one of 48 pairs (64.6%) were successful, and produced 70 nestlings. Productivity was 1.46 nestlings per total pair and 2.26 nestlings per successful (≥1 nestling observed) pair. Between 1975 and 2005, the number of total and successful pairs nesting along the upper Yukon River has been steadily increasing, though the percentage of total pairs nesting successfully has been declining. This maybe attributable to increased competition for resources due to increased density and birds moving into sub-optimal territories (i.e. territories with insufficient resources and cover from predators). Recent contaminants analyses of Peregrine Falcon eggs from YUCH suggest that mercury is currently at levels that may affect reproduction, and trends suggest that mercury levels maybe increasing (Ambrose et al. 2000). Mercury is a persistent compound which bioaccumulates at high trophic levels causing toxic effects (similar to DDT). Additionally, DDT and other pesticides are still being used in wintering grounds, which may cause continued risk to the population. In response to these threats, addled eggs and nestling feathers are collected. In 2005, nestling feather samples were collected from 1 eyrie.

American Peregrine Falcon Monitoring Along the Upper Yukon River, Yukon-Charley Rivers, Alaska, 2005

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