ARCUS | Arctic Research Consortium of the United States

7th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Travis Booms
Authors   Travis L. Booms and M. R. Fuller
Category   Life Science
Title   Gyrfalcon Diet in Central West Greenland During the Nestling Period
Affiliation   Biology, Boise State University, Wausaukee, WI, USA

Abstract

We studied nesting Gyrfalcon (Falco rusticolus) food habits in central West Greenland during the 2000 and 2001 field seasons using time-lapse video (three nests), regurgitated pellets (19 nests), and prey remains (22 nests). Gyrfalcons relied heavily on Rock Ptarmigan (Lagopus mutus) and arctic hare (Lepus arcticus). Combined, these species contributed 79.2 – 90.6% of the total diet, depending on the method used. Passerines contributed the third most percent biomass and percent pellet composition. Three duck species contributed small amounts of biomass to the diet, as did arctic fox (Alopex lagopus) pups. All Rock Ptarmigan items observed were from adult individuals. All but one arctic hare item observed were from young of the year. Most of the passerines were Lapland Longspur (Calcarius lapponicus) fledglings. We observed two diet shifts. The first was a shift from ptarmigan to hare in mid-June, and the second was an influx of passerine fledglings in the diet in late June. The video-monitored Gyrfalcons consumed 94.0-110.1 kg of food per nest during the nestling period, higher than previously estimated. Video and prey remains data gave 1.47 and 1.28 Shannon Wiener H-values, respectively, similar to the mean of other Gyrfalcon diet studies. Using a combination of the three methods was important to accurately document Gyrfalcon diet, and we strongly recommend using time-lapse video in future diet studies to identify biases in traditional prey remains and pellet data.