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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123. No. 3. September 2011 
TABLE 1. Annual breeding home range 
size of six Turkey Vultures in 
central Saskatchewan, Canada. 2005-2009. 
Estimates of 95% fixcd-kemel home ranges were based on a random subsample of 120 locations (all birds). ID - patagial 
tag and transmitter number. 
Vulture ID l Yean 
Dales 
M/F 
n 
95% MCP (km 5 ) 
95% Fixed kernel (km : ) 
H2 57952 (2005) 
19 Jun-13 Aug 
Unk 
945 
953 
1,992 
HO 57953 (2005) 
19 Jun-18 Aug 
Unk 
1,217 
502 
891 
H8 65544 (2007) 
18 Jun-18 Aug 
Unk 
1,342 
261 
316 
T2 65545 (2007) 
17 Jun-19 Aug 
F 
1,320 
416 
567 
T3 85753 (2009) 
22 May-28 Aug 
M 
331 
47 
49 
T4 85754 (2009) 
22 May-28 Aug 
F 
774 
47 
75 
Mean ± SD 
988 ± 392 
371 ± 340 
648 ± 731 
P = 0.98). Home ranges decreased in size from 
2005 to 2009 (fixed-kernel home range size vs. 
year, t = 3.98, P = 0.016, r = 0.80) (Table 1). 
We received good signal reception during early 
incubation, 23-30 May for the pair of adults 
captured at the same nest site (male # 85753 and 
female # 85754), and for the female during 
brooding, 30 June-4 July (Figs. 2, 3). Transmitter 
signals were not received from male # 85753 
throughout most of June and the entire brooding 
period in early July. Both adults took turns 
incubating until the eggs hatched between 25 
and 30 June (Fig. 2); brooding then became 
intensive by the female for about 18 hrs per day 
including each night through 4 July (Fig. 3). 
Brooding ceased entirely after 10 July and a daily 
feeding visit by each adult was so brief that it was 
rarely recorded near the nest house. All-night 
perch sites, rarely used more than once, after 
brooding ceased, were unexpectedly distant for all 
6 adults: up to 37.8, 38.8, 17.7. 29.7, 7.5, and 
15.9 km from the nest house with young 
(Table 2). Vultures ascended to 558, 902, 681. 
and 627 m above the altitude of the nest house 
when searching for carcasses (Table 3). 
DISCUSSION 
There was considerable variation in breeding 
home range size of the Turkey Vultures we 
tracked; we recorded some of the smallest and 
largest breeding ranges recorded for the species. 
What governs home range size can be complex 
(McLoughlin and Ferguson 2000, Peery 2000); 
however, a wide-ranging survey of home range 
size in birds (Rolando 2002) suggests food 
availability is the primary determinant of avian 
range size and all other factors are secondary. We 
suggest heterogeneity in food availability may 
explain variation in the breeding range size for the 
vultures we studied. For example, the small 
breeding range sizes of vultures # 85753 and # 
85754, a mated pair tracked in 2009. were in the 
North Saskatchewan River Valley (Fig. 1). a 
relatively productive riparian area; these vultures 
may have had greater access to food than the other 
four birds in our study. It also is possible that 
carrion availability changed among years, as we 
observed larger breeding ranges earlier in the 4- 
year study than in later years. Large home range 
sizes are made possible, in part, by the species' 
extremely low-cost soaring flight (cf Mandel et 
TABLE 2. Night perches of six Turkey Vultures occupying home ranges in central Saskatchewan. Canada, 2005-2009. 
Distances (km) are from the known nest house to all-night perch sites. 
Patagial tag 
HO 
H2 
H8 
T2 female 
T3 male 
T4 female 
Transmitter # 
Total days 
No. nights at roost 
No. nights at nest house 
Maximum distance (km) 
Mean distance (km) 
Minimum distance (km) 
57953 
61 
61 
0 
37.8 
8.2 
0.62 
57952 
52 
52 
0 
38.8 
21.0 
1.5 
65544 
61 
58 
0 
17.7 
5.6 
0.8 
65545 
64 
60 
0 
29.7 
8.1 
1.1 
85753 
99 
34 
5 
7.5 
2.3 
1.2 
85754 
99 
79 
20 
15.9 
2.4 
0.25 
