The Effects of Unequal Catchability on Jolly-Seber Estimates

Abstract

If the number of immigrants per inter-sample period, and the probabilities of survival, capture and death on capture are all assumed constant in time, the asymptotic biases of the Jolly-Seber estimates arising from a failure of the hypothesis of equal catchability can be derived analytically. The dependence of these biases on the parameters of the model, and of the distribution of catchability, is discussed for stable populations with no deaths on capture, For smaller populations, simulation leads to conclusions consistent with these results and provides information on the suitability of Jolly's formulae for the estimated variances.