The Wilson Journal of Ornithology 123(3):472-478, 2011 
BREEDING HOME RANGES OF MIGRATORY TURKEY VULTURES 
NEAR THEIR NORTHERN LIMIT 
C. STUART HOUSTON,' 7 PHILIP D. McLOUGHLIN. 2 JAMES T. MANDEL, 3 
MARC J. BECHARD, 4 MARTEN J. STOFFEL, 25 
DAVID R. BARBER, 6 AND KEITH L. BILDSTEIN 6 
ABSTRACT.—We used Global Positioning System (GPS) satellite transmitters to estimate the breeding home ranges of 
Turkey Vultures (Cathartes aura) in Saskatchewan. Canada from 2005 to 2009. Breeding ranges calculated using 95% 
Minimum Convex Polygons (MCP) ranged from 47 to 953 km’ and averaged (± SD) 371 ± 340 km 2 . Fixed-kernel home 
ranges (95%) ranged from 49 to 1,992 kin* and averaged 648 ± 731 knr. These ranges include both the smallest and largest 
summer ranges reported tor the species. Spatial variation in range si/e may have been due to differences in availability of 
food and the quality of the home ranges involved, amplified by the species' extremely low-cost soaring flight. Adults used 
all-nighr porches in varying locations up to 38 knt front their nest house while traveling substantial distances to available 
carcasses to obtain food for their young. Identifying home range si/es for Turkey Vultures is a first step toward 
understanding how the species is increasing and expanding its distribution in Saskatchewan and elsewhere in Canada. 
Received 2H May 2010. Accepted 17 January 2011. 
Both Old and New World vultures are obligate 
scavenging birds (Rea 1983, Kirk and Mossman 
1998). The scavenging niche has ecological 
requirements that differ from those of more 
predatory raptors (Wilbur and Jackson 1983. 
Mundy et al. 1992). Feeding on carcasses, which 
can be highly ephemeral and unpredictable (Kelly 
et al. 2007), often requires breeding vultures to 
range widely in search of food for their develop¬ 
ing young (e.g.. Kirk and Mossman 1998). Turkey 
Vultures (Cathartes aura) exhibit considerable 
variation in size of home ranges, both within and 
among geographic areas. Home ranges of non¬ 
breeding vultures captured at communal roosts 
varied from 128 to 1.227 km 2 in southeastern 
Minnesota (Tenney 1986). 91 to 482 km 2 in South 
Carolina (DeVault et al. 2004). 149 knr in Ohio 
to 627 knr in Indiana (Arrington 2003). and 149 
to 371 km 2 at Gettysburg in southern Pennsylva¬ 
nia and northern Maryland (Coleman and Fraser 
1989). 
Turkey Vultures breed from Canada to southern 
South America, adapt well to grasslands, deserts, 
' 863 University Drive, Saskatoon, SK S7N 0J8, Canada. 
-Department of Biology. University of Saskatchewan 
112 Science Place. Saskatoon. SK S7N 5E2. Canada. 
3 Department of Ecology and Evolutionary Biology, 
Corson Hall, Cornell University, Ithaca, NY 14853, USA. 
4 Raptor Research Center. Department of Biological 
Sciences. Boise Slate University. Boise. ID 83725, USA. 
ioiS l ^o, addreSs: 2322 Lombard Street, Philadelphia. PA 
<yi46, LSA. 
Acopian Center for Conservation Learning. Ha 
ountain Sanctuary, Orwigsburg, PA 17961. USA 
Corresponding author; e-mail: stuart.houston@usask 
deciduous and mixcd-deciduous forests, and open 
and forested tropical lowlands: they are the most 
widely distributed scavenging bird in the world 
(Wilbur 1983. Ferguson-Lees and Christie 2001). 
Individuals can be found year-round in the 
southern United States, hut more northerly 
breeders migrate from breeding areas to overwin¬ 
ter in the southern United Slates, Central America, 
and northern South America (Chapman 1933. 
Stewart 1977, Kirk and Mossman 1998. Mandelet 
al. 2011). The most northern breeding populations 
are in western Canada, including central Sas¬ 
katchewan. This recent expansion of vulture 
distribution coincided with an increase in use of 
long-abandoned farm buildings as nesting sites 
(Houston et al. 2007). 
We have few data on the breeding ecology of 
Turkey Vultures, apart from locations and char¬ 
acteristics of nest sites, near the northern limits of 
their range. In particular, we know little concern¬ 
ing size of iheir breeding home ranges. Our 
objectives were to: (I) document the size of 
breeding home ranges of Turkey Vultures in 
central Saskatchewan, and (2) test the hypothesis 
that size of home ranges near the periphery of 
their range would be larger than farther south. 
Macro-ecological theory suggests that, unless 
there are abrupt changes in habitat types at the 
limits of a species’ range, individuals should be 
more concentrated at the center of the range than 
near its boundaries (Brown 1984, 1995), possibly 
because of higher competition for food (Gross and 
Price 2000). Thus we initially predicted larger 
home range sizes for Turkey Vultures than 
previously reported. 
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