13/07/2018
Understanding what environmental
cues birds use to time their annual migrations and decide where to settle is
crucial for predicting how they'll be affected by a shifting climate.
A new study from The Auk:
Ornithological Advances shows that for two species of tyrant flycatcher,
one of the key factors is rain – the more precipitation an area receives, the
more likely the birds are to be there during the non-breeding season.
Tulane University's Maggie
MacPherson and her colleagues combined field techniques with species
distribution models to investigate which environmental factors drove the
migrations of Eastern
Kingbirds and Fork-tailed
Flycatchers. Using geolocators, devices that record a bird's daily
location based on day length, they could track where individuals of each
species went. The two species share similar behaviour and habitat requirements,
but differ in their range and migration strategies, and these strategies were
compared to determine the influence of temperature, precipitation and
primary productivity (that is, the amount of 'green' vegetation). Precipitation
turned out to be one of the most important predictors of their distribution,
particularly in the non-breeding season.
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