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Demographic features of a lapland longspur population near Barrow Alaska

Auk

By:
and

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Abstract

Breeding density, clutch size, hatching and fledging success, and survival of adult Lapland longspurs (Calcarius lapponicus) were monitored over a 7 yr period near the Naval Arctic Research Laboratory, Barrow, Alaska [USA]. Nesting begins as soon as the tundra starts to clear of snow and appears to be timed so that the young of the year reach independence before the end of adult insect emergence. Arthropod prey become abruptly scarce after the period of insect emergence and thus probability of success for late broods is low. Time of nesting is also discussed in relation to factors of predation and timing of molt. At least 42.9% of males and 45.4% of females survived the next season after 1 yr of age. Maximum longevity observed for both sexes was 6 yr. Mean clutch size for all years investigated was 5.06 eggs per clutch. Clutch size showed both yearly and seasonal variation. The data indicate that timing of nesting is the chief factor in the observed clutch size differences, further modified by habitat quality, second nesting attempts and probably age of female. Over a 4 yr period the longspur breeding population on a 17 ha study plot declined from 15 to 2 breeding females. Life-table analysis indicates that low fledgling success for 3 consecutive years apparently was the main cause of this decline. Overall mean egg success was 44.0%, but close to 60% in 4 yr is considered more normal. The low egg success was due to 3 consecutive years of high predation, which may have been related to the disrupted lemming cycle of the Barrow region.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Demographic features of a lapland longspur population near Barrow Alaska
Series title:
Auk
Volume
94
Issue:
3
Year Published:
1977
Language:
English
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
pp. 505-525
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Auk
First page:
505
Last page:
525
Number of Pages:
21