Developing Gyrfalcon Surveys and Monitoring for Alaska.

Abstract

ABSTRACT.-We developed methods to monitor the status of Gyrfalcons in Alaska. Results of surveys and monitoring will be informative for resource managers and will be useful for studying potential changes in ecological communities of the high latitudes. We estimated that the probability of detecting a Gyrfalcon at an occupied nest site was between 64% and 87% depending on observer experience and aircraft type (fixed-wing or helicopter). The probability of detection is an important factor for estimating occupancy of nesting areas, and occupancy can be used as a metric for monitoring species' status. We conclude that surveys of nesting habitat to monitor occupancy during the breeding season are practical because of the high probability of seeing a Gyrfalcon from aircraft. Aerial surveys are effective for searching sample plots or index areas in the expanse of the Alaskan terrain. Furthermore, several species of cliff-nesting birds can be surveyed concurrently from aircraft. Occupancy estimation also can be applied using data from other field search methods (e.g., from boats) that have proven useful in Alaska. We believe a coordinated broad-scale, inter-agency, collaborative approach is necessary in Alaska. Monitoring can be facilitated by collating and archiving each set of results in a secure universal repository to allow for statewide meta-analysis.

Use of Large-scale, Multi-species Surveys to Monitor Gyrfalcon and Ptarmigan Populations.

“…One of the strengths of this approach is that the stratification can be adapted to local needs as was done, for example, in the Mackenzie Delta in response to concerns about the effects of oil development on birds (Rausch and Johnston in press). Stratification in the PRISM surveys has not yet focused on cliff-nesting raptors, probably because raptor biologists have not been deeply involved with the designers of PRISM, yet this might be accomplished (e.g., Ritchie et al 2003, Booms et al 2010, Fuller et al 2011, Mossop 2011 for future PRISM surveys. Pilots and observers conducting aerial surveys must focus on the priority species (usually waterfowl), yet if reasons existed to distinguish falcons, it is possible that those workers would do so.…”