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High Latitude Foraging in a Homeothermic Bird
This just in (has implications for high latitude cold weather
and cycle dinosaurs, et al.):
Systad, G.H. & Bustnes, J.O. 2001. Coping with darkness and low
temperatures: foraging strategies in Steller's eiders,
Polysticta stelleri, wintering at high latitudes. _Canadian
Journal of Zoology [Revue canadienne de zoologie]_ 79: 402-406.
[make sure the rest of the link that does not possess a
clickable interface is with the URL in the new window, or you
cann't follow it.]
Abstract: To examine how Steller's eiders, Polysticta stelleri,
wintering at 70°N cope with adverse winter conditions in terms
of darkness and low temperatures, we studied their feeding
behaviour during four periods between late autumn and early
spring. Steller's eiders were most likely to feed during
daylight and twilight, but they also fed during darkness. The
incidence of feeding was highest at low tide, and there was a
significant interaction between tidal cycle and winter period.
Hence, the birds fed more intensively at low tide in midwinter
(January) than during the other periods. Air temperatures were
between 8 and 10°C lower in midwinter than during the other
periods, and during this period the eiders also fed more by
means of nondiving techniques (up-ending, surface feeding). The
total estimated feeding time was highest in late autumn and
midwinter (5.9 and 6.3 h were spent actively feeding,
respectively) and lower in late winter and spring (5.1 and 4.6
h, respectively). Thus, as energy requirements increased as a
result of low temperatures, Steller's eiders increased their
feeding effort, but also reduced feeding costs by reducing
diving depth. The results of this study suggest that the
Steller's eider is behaviourally well adapted to survive winter
at high latitudes at relatively low stress.
Has implications for the Coleville River and Dinosaur Cove
faunas at high latitudes, but I've not read the paper.
Jaime A. Headden
Where the Wind Comes Sweeping Down the Pampas!!!!
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