Factors associated with survival of reintroduced riparian brush rabbits in California

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• 作者：Laurissa P. Hamilton ; Patrick A. Kelly ; Daniel F. Williams ; Douglas A. Kelt ; Heiko U. Wittmer
• 关键词：Survivorship ; Reintroduction ; Controlled propagation ; Program MARK ; Sylvilagus bachmani ; Endangered species
• 刊名：Biological Conservation
• 出版年：2010
• 出版时间：April 2010
• 年：2010
• 卷：143
• 期：4
• 页码：999-1007
• 全文大小：411 K

文摘

The riparian brush rabbit (Sylvilagus bachmani riparius) is an endangered species found in dense, brushy habitat in the California’s Central Valley. We implemented a reintroduction program to bolster populations at a Federal Wildlife Refuge and to assess factors influencing mortality and subsequent survival of released individuals. Between July 2002 and July 2005, we reintroduced 325 captive-bred individuals to unoccupied habitat within their historic range using a soft-release strategy and monitored their subsequent survival with radiotelemetry. Longer time in soft-release pens resulted in increased monthly survival. Rabbits were most susceptible to post-release mortality during the first 4 weeks following reintroduction and both body mass and length of time in the soft-release enclosure influenced this relationship. When we controlled for release mortality during this acclimation period, subsequent monthly survival probabilities were most strongly influenced by release year (year 1 vs. years 2 and 3) and by a catastrophic flooding event; length of time in the soft-release enclosure remained an important variable in longer-term survival. Cause of mortality was unknown for the majority of deaths (61.9 % ), but predation (including presumptive predation) was the greatest known cause of death in translocated rabbits (26.4 % ). Reintroduction programs should employ an adaptive management approach with ongoing monitoring of target animals and concurrent analysis to allow managers to adjust methods as conditions dictate.