Modelling the survival of British Lapwings Vanellus vanellus using ring-recovery data and weather covariates

Two sets of data are considered. One describes recovery data from Lapwings ringed as young in Britain in 1963-92. The other provides several weather covariates for the same period, and our objective is to try to relate these two data sets. We use score tests, provided by the computer package Eagle, to build a simple model which describes the data well. We first establish a need for time variation in the three basic elements of the model: first-year annual survival probability, adult annual survival probability and reporting probability. We then investigate the direct incorporation of covariates, using score tests, to give a limited set of models to compare. The final choice between these models is based on the Akaike information criterion (Alc). We find that adult annual survival is negatively related to measures of winter weather severity. In contrast to previous work, we have found a pronounced decline of reporting rate with time. Our methods produce appreciably higher estimates of adult survival than those previously obtained using methods which assumed reporting rates to be constant over time.