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Nest and chick survival and colony-site dynamics of least terns in the U.S. Virgin Islands

The Condor

By:
, , and
DOI: 10.1525/cond.2010.090042

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Abstract

We report nest and chick survival and colony-site dynamics of the Least Tern (Sternula antillarum). These results are the first for the Caribbean and were derived with likelihood-based approaches from 4640 nests and 44 chicks fitted with transmitters monitored in 52 colonies at St. Croix, U.S. Virgin Islands, 2003–2006. Managed colonies excluded, overall daily nest survival (±SE) was 0.92 ± 0.03 (period survival = 0.18). Daily nest survival of managed colonies (fenced) was significantly higher (0.97 ± 0.02; period survival = 0.51). Variation in nest survival was best explained by a negative linear trend in daily survival, influenced by year, rain, large colony size, and nesting habitat. Daily nest-survival rates at sandy beaches (0.94 ± 0.02), offshore cays (0.93 ± 0.005), and saltflats (0.91 ± 0.02) did not differ significantly. The period survival of chicks was 0.30 ± 0.11. Estimated fledglings per nest attempt were 0.06. Demographic assessments suggested that higher reproductive rates are required for maintenance (λ ≥ 1). Managed colonies could meet nest-survival thresholds, but complementary measures are needed to increase chick survival. Our findings suggest that management should target sites harboring large colonies because they had higher nest success and higher probability of use in subsequent seasons. The colonies' site dynamics suggested that immigration from other populations is plausible. This possibility relaxes breeding-productivity thresholds and advocates for coordinated conservation among populations on neighboring islands. Estimates of age-specific survival and connectivity are needed for the status of the species to be assessed appropriately and conservation priorities set.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Nest and chick survival and colony-site dynamics of least terns in the U.S. Virgin Islands
Series title:
The Condor
DOI:
10.1525/cond.2010.090042
Volume
112
Issue:
1
Year Published:
2010
Language:
English
Publisher:
Cooper Ornithological Society
Contributing office(s):
Coop Res Unit Atlanta
Description:
9 p.
First page:
56
Last page:
64
Country:
U.S. Virgin Islands
Online Only (Y/N):
N
Additional Online Files(Y/N):
N