Kirchman et al. • MIGRATION STOPOVER IN AN INLAND PINE BARREN 
551 
so results are comparable to 6 D { measured in 
olher major research laboratories. Feathers were 
handled only with fine forceps during washing 
and subsequent processing. 
A series of /-tests performed within each species 
indicated no significant differences in hydrogen 
isotope values from feathers collected in different 
years, and we pooled data from all 3 years in 
subsequent analyses. We regressed &D,- on capture 
date to examine possible trends with respect to 
liming of stopover of birds from different breeding 
localities. We converted 6D f to altitude-corrected 
growing-season precipitation values (5£) p ) using the 
equation 5£) p = 5D, - 25%o (Maze nolle et al. 2005) 
and compared these to the growing season SD V map 
for North America constructed by Meehan ct al. 
(2004). We used ArcGIS (9.3.1) to overly the 5D p 
map with digital maps of the breeding ranges for 
each species taken from Ridgely et al. (2007; 
downloaded from http://www.natureserve.org/ 
geiData/birdMaps.jsp). Area of origin maps were 
produced by highlighting the intersection of the 
breeding range with the observed range of 8D P 
values we calculated for each species. 
RESULTS 
We banded 244 migratory birds from 32 
species in 8,610 net/m/hrs over 3 years (Fig. 2). 
Both number of migrants captured per unit effort 
and species diversity peaked in mid- to late- 
Sepiember, weeks 2 and 3 of our 6-week survey 
period (Fig. 2). Most species pass through the 
APBP in 2 or 3 weeks, but Nashville Warbler and 
Yellow-rumped Warbler (Demlroka coronata) 
are present over the course of 5 weeks. No 
species was captured in both the first and last 
week of the survey period. The fall migration 
begins with a trickle of warblers, quickly builds to 
a diverse assemblage of songbirds from several 
passeriform families, and ends with a large influx 
°f cold-tolerant species, mostly sparrows that 
breed at very high latitudes and altitudes. 
Stable hydrogen isotope values from feathers 
'°Of) of six species ranged widely, indicating the 
birds came from breeding sites across the boreal 
forest (Table 1). Mapped W p calculated from 6D f 
measurements overlapped with known breeding 
ranges of all species. Slopes of regressions between 
date of capture and 6D, were not statistically 
different from zero for all species (all r 2 < 0.05, all 
p > 0.05). We found no correlations to indicate 
that individuals from more southerly breeding 
areas arrived earlier (chain migration) or that more 
FIG. 2. Autumn migrants captured on the Albany Pine 
Bush Preserve during 6-week mist-net surveys in 2007, 
2008. and 2009. Totals are for all 3 years combined. 
