A simultaneous survival rate analysis of dead recovery and live recapture data

In long term studies on birds one frequently encounters both dead recovery data, from birds marked as young, and live recapture data, typically from birds ringed as breeding adults. However the two types of data have usually been analysed separately, using different computer software. In this paper we show how related but independent sets of recovery and recapture data may conveniently be analysed simultaneously using just one computer package for model fitting by maximum likelihood. A weighted least squares analysis provides a direct way of assessing the relative contributions of the two types of information. Data on the Herring Gull Larus argentatus are used to illustrate the approach. By showing how recovery information can be analysed by the program SURGE, we provide a useful tool for the analysis of such data.