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1 August 2013 Reproductive Ecology of the Island Scrub-Jay
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Abstract

We investigated the reproductive ecology of the Island Scrub-Jay (Aphelocoma insularis), which is endemic to Santa Cruz Island, California, and is a species of conservation concern. We documented daily nest survival, probability of renesting, annual fledging success, and breeding behavior, and determined how these factors varied in relation to the habitat characteristics of the jays' home ranges. Clutch sizes, feeding rates, and nest attendance were not correlated with chaparral cover or with home-range size. In contrast, nest predation, which accounted for 92% of documented nest failures, was less likely at nests that were more concealed, at nests of breeding pairs with home ranges that were smaller and had a greater proportion of taller vegetation, and at nests that were initiated earlier in the breeding season. Researchers' activity near nests increased the likelihood of predation, although the effect diminished with a nest's age. Despite relatively low nest survival, the high frequency of renesting allowed pairs to fledge an average of 1.1 ± 0.1 young per year, or 1.8 ± 0.2 young after the effects of the observer were accounted for. Currently, chaparral habitats on Santa Cruz Island are regenerating following the removal of exotic herbivores. This regeneration could in turn increase and improve breeding habitat for this island endemic.

© 2013 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website, http://www.ucpressjournals.com/reprintInfo.asp.
Luke Caldwell, Victoria J. Bakker, T. Scott Sillett, Michelle A. Desrosiers, Scott A. Morrison, and Lisa M. Angeloni "Reproductive Ecology of the Island Scrub-Jay," The Condor 115(3), 603-613, (1 August 2013). https://doi.org/10.1525/cond.2013.120028
Received: 13 February 2012; Accepted: 1 December 2012; Published: 1 August 2013
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