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Are declines of an endangered mammal predation‐driven, and can a captive‐breeding and release program aid their recovery?
Author(s) -
McCleery R.,
Oli M. K.,
Hostetler J. A.,
Karmacharya B.,
Greene D.,
Winchester C.,
Gore J.,
Sneckenberger S.,
Castleberry S. B.,
Mengak M. T.
Publication year - 2013
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/jzo.12046
Subject(s) - biology , predation , population , endangered species , captive breeding , zoology , population size , ecology , population growth , mark and recapture , demography , habitat , sociology
Declines of imperiled small mammals are often attributed to predation without investigating the relative influence of survival and reproductive parameters on population growth. Accordingly, declines in the endangered K ey L argo woodrat N eotoma floridana smalli ( KLWR ) population have been attributed to predation by feral cats F elis catus , Burmese pythons P ython molurus bivittatus and raccoons P rocyon lotor . We estimated survival, recruitment and realized population growth rates from four capture–mark–recapture studies to determine if the pattern of demographic variation was consistent with predation as the primary cause of KLWR declines. Additionally, we evaluated the KLWR captive‐breeding and release program by comparing survival of captive‐born and released KLWR s to wild‐born KLWR s. The realized population growth rate of wild‐born KLWR s had a strong pattern of covariation with recruitment; covariation between the realized population growth rate and apparent survival was negligible. Consistent with demographic theory, our results suggest that KLWR population dynamics were driven primarily by variation in recruitment, and that periodic reductions in recruitment led to population declines. We found that the survival curve and the first month ( S 1 ) and first 3‐month ( S 1–3 ) survival estimates for the wild‐born KLWR s [ S 1 = 0.929 (0.890–0.968); S 1–3 = 0.942 (0.919–0.965)] were considerably higher ( χ 2 = 33.9, 1 d.f., P < 0.001) than released KLWR s [ S 1 = 0.521 (0.442–0.600); S 1–3 = 0.561 (0.493–0.629)]. Low survival rates from predation limited the success of the captive‐breeding and release program. This study illustrates the importance of pre‐release conditioning of captive‐bred animals and the importance of considering reproductive parameters in conjunction with survival estimates to understand the drivers of population decline.