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The influence of morphological variation on migration performance in a trans-hemispheric migratory songbird
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For long-distance migratory songbirds,
morphological traits such as longer wings and a smaller
body size are predicted to increase migration efficiency.
Due to previous limitations in our ability to track the
long-distance journeys of small-bodied birds, the
relationship between morphology and start-to-finish
migration performance has never been fully tested in
free-living songbirds. Using direct-tracking data obtained
from light-level geolocators, we examined the effects of
morphological factors (wing and body size) on spring
and fall migration performance (flight speed, duration of
stopovers, total stopovers taken) of a widely distributed,
trans-hemispheric migratory songbird, the purple martin
(Progne subis) (n = 120). We found that smaller-bodied
birds spent fewer days at stopovers along fall migration,
but larger-bodied birds spent fewer days at stopover and
took fewer stopovers during spring migration. More of the
variation in fall migration performance was explained
by morphology, as compared to spring migration,
possibly indicating a larger influence of environmental
conditions on spring performance. Overall, our results
partially support long-standing and previously untested
predictions regarding the influence of intrinsic factors on
migration performance. Future research should examine
the influence of environmental variation on migration
performance as well as additional morphological traits
that may contribute to migration performance. -
- Date created
- 2015-01-01
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- Subjects / Keywords
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- Type of Item
- Article (Published)