530 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol 123, No. 3, September 2011 
1.4 
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1 
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36 38 
40 
42 44 
46 
48 
y = 0.0061x + 0.5317 
^=0.0084 
Latitude bar(°N) 
F, |=0.085 
P = 0.78 
across eastern North America bSons". ° f SaW * Whc « ° wl events during fa 
America, based on 81.184 banding events. 1999-2008. grouped into 01 latitude bars. 
This type of tunneling may explain why 41% G f 
owls in our fidelity analysis were banded and 
recaptured at two stations west of Lake Michigan 
It may be argued this potential geographic 
funnelmg biases fidelity estimates. However 
similar circumstances of restricted movement’ 
would be required throughout the year to 
challenge migration route fidelity estimates. 
early, there was ample opportunity for these 
individuals to move southward along the other 
side of the lake or to take a different route void of 
the Great Lakes influence. Consistent repeated 
movement along the same corridor duriim fall 
migration, constricted or not. is a valid assessment 
of route fidelity. It is possible that some owls 
encountered at these two sites were residents, but 
similar fidelity measures were found in the Great 
Lakes Basin when these stations were removed. 
and in regions where few resident owls are present 
(Rasmussen ct al. 2008). The lack of significant 
difference in fidelity measures among the Great 
Lakes Basin and other regions suggests that 
geologic constraints do not fully explain the high 
route fidelity indicated by our analysis. High 
fidelity was observed in the Appalachian Moun¬ 
tains where movement is unlikely restricted by 
geologic features, but may be selected for 
structural and resource benefits, showing that 
Northern Saw-whet Owls may follow consistent 
routes where geographic bottlenecks are not 
present. 
Our study addresses migration route fidelity 
rather than nesting-site fidelity, but our results 
contribute to the ongoing discussion of nomadic 
behavior in Northern Saw-whet Owls (Marks and 
Doremus 2000. Bowman et al. 2010). Our 
each year. 1999-2008. tl0nship hctween adult-to-juvemle ratio (y) and latitude bar (x) for Northern Saw-whet Owls in 
1999 
2000 
2001 
2002 
2003 
2004 
2005 
2006 
2007 
2008 
0.009x 
- 0 . 
0 
0.012 
I46x + 8.124 
037x - 0.894 
054x + 3.386 
042x + 2.473 
026x + 2.542 
OI9x + 0.280 
039x + 2.373 
>27x - 0.556 
66 x + 36.943 
0.027 
0.268 
0.118 
0.233 
0.414 
0.058 
0.066 
0.398 
0.076 
0.740 
0.277 
3.657 
1.335 
3.04 
7.066 
0.617 
0.712 
5.950 
0.826 
29.770 
11 
11 
11 
11 
11 
II 
11 
0.61 
0.085 
0.275 
0.112 
0.024 
0.45 
0.419 
0.037 
0.385 
0.0003 
10,676 
5,873 
6.995 
6,114 
9,276 
8,192 
8,328 
7,185 
14,202 
4,343 
