Estimation of contributions to population growth: A reverse-time capture-recapture approach

We consider methods for estimating the relative contributions of different demographic components, and their associated vital rates, to population gro wth. We identify components of the population at time i (including a compon ent for animals not in the population at i). For each such component we ask the following question: "What is the probability that an individual random ly selected from the population at time i + 1 was a member of this componen t at i?" The estimation methods for these probabilities (gamma (i)) are bas ed on capture-recapture studies of marked animal populations and use revers e-time modeling. We consider several different sampling situations and pres ent example analyses for meadow voles. Microtus pennsylvanicus. The relatio nship between these gamma (i) parameters and elasticities (and other parame ters based on projection matrix asymptotics) is noted and discussed. We con clude by suggesting that model-based asymptotics be viewed as demographic t heory and that direct estimation approaches be used to test this theory wit h data from sampled populations with marked animals.