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Factors influencing Soay sheep survival

Catchpole, Edward A., Morgan, Byron J. T., Coulson, Tim, Freeman, Stephen N., Albon, Steve D. (2000) Factors influencing Soay sheep survival. Journal of the Royal Statistical Society: Series C (Applied Statistics), 49 . pp. 453-472. ISSN 0035-9254. (doi:10.1111/1467-9876.00205) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:16246)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided.
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We present a survival analysis of Soay sheep mark recapture and recovery data. Unlike previous conditional analyses, it is not necessary to assume equality of recovery and recapture probabilities; instead these are estimated by maximum likelihood. Male and female sheep are treated separately, with the higher numbers and survival probabilities of the females resulting in a more complex model than that used for the males. In both cases, however, age and time aspects need to be included and there is a strong indication of a reduction in survival for sheep aged 7 years or more. Time variation in survival is related to the size of the population and selected weather variables, by using logistic regression. The size of the population significantly affects the survival probabilities of male and female lambs, and of female sheep aged 7 or more years. March rainfall and a measure of the North Atlantic oscillation are found to influence survival significantly for all age groups considered, for both males and females. Either of these weather variables can be used in a model. Several phenotypic and genotypic individual covariates are also fitted. The only covariate which is found to influence survival significantly is the type of horn of first-year female sheep. There is a substantial variation in the recovery probabilities over time, reflecting in part the increased effort when a population crash was expected. The goodness of fit of the model is checked by using graphical procedures.

Item Type: Article
DOI/Identification number: 10.1111/1467-9876.00205
Uncontrolled keywords: integrated analysis; logistic regression; mark recapture; mark recovery; maximum likelihood; Soay sheep; survival
Subjects: H Social Sciences > HA Statistics
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Mathematics, Statistics and Actuarial Science
Depositing User: P. Ogbuji
Date Deposited: 06 Apr 2009 08:18 UTC
Last Modified: 16 Nov 2021 09:54 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Catchpole, Edward A..

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Morgan, Byron J. T..

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