Based on Travis Booms’ thesis research, we investigated gyrfalcon (Falco rusticolus) food habits in Central West Greenland near Kangerlussuaq, Greenland in 2000 and 2001. Our research was funded primarily by The National Science Foundation, The Peregrine Fund, Inc., and the Boise State University Raptor Research Center. We were assisted by many persons but especially in the field collecting data: Ryan Blaedow, Gregg Doney, Catherine Wightman, Jim Mussell, Kurt Burnham, Bill Burnham, Alberto Palleroni, and Ron Vander Velden. We thank Bent Brodersen, Robin Abbot, Tom Quinn, Diana Garcia-Novick, Ed Stockard, Kangerlussuaq International Science Support, and VECO Polar Resources for invaluable logistics support. Dotty Douglas, Bill Mattox, and Bob Rosenfield provided very helpful reviews and comments in preparing manuscripts.
We used three sources of data: time-lapse video (3 nests), prey remains (22 nests), and regurgitated pellets (19 nests) to study food habits. These sources provided different information describing the diet during the nesting period. Gyrfalcons relied heavily on rock ptarmigan (Lagopus mutus) and arctic hares (Lepus arcticus). Combined, these species contributed 79–91% of the total diet, depending on the data used. Passerines were the third most important group. Prey less common in the diet included waterfowl, arctic fox pups (Alopex lagopus), shorebirds, gulls, alcids, and falcons. All rock ptarmigan were adults, and all but one arctic hare were young of the year. Most passerines were fledglings. We observed two diet shifts, first from a preponderance of ptarmigan to hares in mid-June, and second to passerines in late June. The video-monitored gyrfalcons consumed 94–110 kg of food per nest during the nestling period, higher than previously estimated. Using a combination of video, prey remains, and pellets was important to accurately document gyrfalcon diet, and we strongly recommend using time-lapse video in future diet studies to identify biases in prey remains and pellet data.
From the time-lapse video cameras installed at three nests, we recorded 2677.25 hours of nestling video. Ptarmigan delivered to nests were usually plucked prior to delivery and included the breast and superior thoracic vertebrae. Arctic hare leverets were rarely plucked and often delivered in parts. The most commonly delivered leveret part was the hind legs attached to the lower back. Passerines were rarely plucked and usually delivered whole. After feeding, adults removed 20.9% of prey items including those with and without obvious muscle still attached. Prey delivery rates were similar among nests and increased as nestlings aged. Prey delivery frequency peaked in the morning and evening, with a distinct lull in the late evening and early morning hours. Male and female adults delivered a similar number of prey, though males typically delivered smaller prey than females. Gyrfalcons cached and re-delivered at least 9.1% of all items delivered and cached some items multiple times.
We used solar-powered time-lapse video photography to document food deliveries and feeding behavior at the nest. The 2,677.25 h of videotape from three nests, represented 94, 87, and 49% of the nestling period at each nest. The video recorded 921 deliveries of 832 prey items. We placed 95% of the items into prey categories. The image quality was good but did not reveal enough detail to identify most passerines to species. We found no evidence that gyrfalcons were negatively affected by the video system after the initial camera set-up. The video system experienced some mechanical problems but proved reliable. The system likely can be used to effectively document the food habits and nesting behavior of other birds, especially those delivering large prey to a nest or other frequently used site.
Booms, T.L. and M.R. Fuller. 2003. Gyrfalcon diet in central west Greenland during the nesting period. The Condor 105:528-537
Booms, T.L. and M.R. Fuller. 2003. Gyrfalcon feeding behavior during the nestling period in central west Greenland. Arctic 56:341-348
Booms, T.L. and M.R. Fuller. 2003. Time-lapse video system used to study nesting Gyrfalcons. Journal of Field Ornithology 74:416-422.
Publications since Boise State University graduate school:
Booms, T. 2012. Banded Alaskan Gyrfalcon discovered in Arabian falconry. Journal of Raptor Research 46:226-227.
Booms, T., L. Parrett, and M. Keech 2012. Use of a net-gun to safely capture Short-eared Owls in mid-flight from a helicopter. Journal of Raptor Research 46:208-211.
Booms, T., S. Talbot, G. Sage, B. McCaffery, K. McCracken, and P. Schempf. 2011. Nest site fidelity and dispersal of Gyrfalcons estimated by non-invasive genetic sampling. Condor 113:768-778.
Booms, T., M. Lindgren, and F. Huettmann. 2011. Linking Alaska’s predicted climate, Gyrfalcon, and ptarmigan distributions in space and time: A unique 200 year perspective. Pp. 177-190 in R.T. Watson, T.J. Cade, M. Fuller, G. Hunt, and E. Potapov (eds), Gyrfalcons and Ptarmigan in a Changing World, Vol. I, The Peregrine Fund, Boise, ID.
Matz, A., T. Swem, P. Johnson, T. Booms, and C. White. 2011. Contaminants and breeding Gyrfalcons: potential for climate change to increase exposure and effects. Pp. 161-175 in R.T. Watson, T.J. Cade, M. Fuller, G. Hunt, and E. Potapov (eds), Gyrfalcons and Ptarmigan in a Changing World, Vol. I, The Peregrine Fund, Boise, ID.
Fuller, M., P. Schempf, and T. Booms. 2011. Developing Gyrfalcon surveys and monitoring for Alaska. Pp. 275-282 in R.T. Watson, T.J. Cade, M. Fuller, G. Hunt, and E. Potapov (eds), Gyrfalcons and Ptarmigan in a Changing World, Vol. I, The Peregrine Fund, Boise, ID.
McCaffery, B., T. Booms, T. Doolittle, F. Broerman, J. Morgart, and K. Sowl. 2011. The ecology of Gyrfalcons on the Yukon-Kuskokwim Delta, Alaska. Pp. 191-220 in R.T. Watson, T.J. Cade, M. Fuller, G. Hunt, and E. Potapov (eds), Gyrfalcons and Ptarmigan in a Changing World, Vol. I, The Peregrine Fund, Boise, ID.
Rosenfield, R., T. Booms, K. Burnham, B. McCaffery, and R. Goodwin. 2011. The potential for long-term monitoring and research of Gyrfalcon and Peregrine Falcon breeding populations using undergraduate students: an apparent inexhaustible source of funding. Pp. 373-384 in R.T. Watson, T.J. Cade, M. Fuller, G. Hunt, and E. Potapov (eds), Gyrfalcons and Ptarmigan in a Changing World, Vol. I, The Peregrine Fund, Boise, ID.
Booms, T.L., P.F. Schempf, and M.R. Fuller 2011. Preening behavior of adult Gyrfalcons tagged with backpack transmitters. Journal of Raptor Research 45:264-267.
Booms, T.L. 2010. Gyrfalcon breeding biology in Alaska. PhD dissertation, University of Alaska Fairbanks, Fairbanks, AK.
Booms, T.L, P.F. Schempf, B.J. McCaffery, M.S. Lindberg, and M.R. Fuller. 2010. Detection probability of cliff-nesting raptors during helicopter and fixed-wing aircraft surveys in Western Alaska. Journal of Raptor Research 44:175-187.
Booms, T.L., J.S. Whitman, and C.L. Gardner. 2010. Utility of helicopters for Short-eared Owl nest searching and surveys. Journal of Raptor Research 44:247-248.
Booms, T.L., F. Huettmann, and P.F. Schempf. 2009. Gyrfalcon nest distribution in Alaska based on a predictive model. Polar Biology 33:347-358.
Rosenfield, R. N., J. Bielefeldt, L. J. Rosenfield, T. Booms, and M. A. Bozek. 2009. Survival rates and lifetime reproduction in breeding male Cooper’s Hawks in Wisconsin, 1980-2005. Wilson Journal of Ornithology 121:610-617.
Booms, T., B. J. McCaffery, and P. Schempf. 2008. Molted feather persistence and aging in a sub-Arctic environment. Condor 110:756-762.
Booms, T.L., N. J. Clum, and T. J. Cade. 2008. Gyrfalcon (Falco rusticolus). In The Birds of North America Online, No. 114 (A. Poole and F. Gill, Eds.). Ithaca: Cornell Laboratory of Ornithology.
Booms, Travis and B. J. McCaffery. 2007. A novel use of passive integrated transponder (PIT) tags as nest markers. Journal of Field Ornithology 78: 83-86.
Booms, Travis. 2006. The Gyrfalcon, a book review. Quarterly Review of Biology. 81:185-186.