Date: September 5, 2018
Source: American Ornithological Society Publications
Office
Animals' lives tend to follow a
quicker tempo as they get farther from the equator -- birds at more northern
latitudes mature faster, start reproducing younger, and live shorter lives,
probably as a way of dealing with seasonal variation in resources. A new study
from The Auk: Ornithological Advances shows for the first time that this
pattern also plays out in birds' feathers, with northern birds completing their
annual molt faster to keep up with the demands of life far from the tropics.
Louisiana State University's Ryan
Terrill looked at museum specimens of four bird species with ranges that span a
wide swath of latitude in both the Northern and Southern Hemispheres. Slight
differences in feather growth between day and night during birds' annual molt
produce visible pairs of light-colored bars, each pair representing 24 hours'
growth. Terrill could determine the rates at which individual feathers grew by
measuring their spacing. He found that for all four species, individuals
collected at higher latitudes had grown their feathers faster.
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