Modeling and estimation of stage-specific daily survival probabilities of nests

In studies of avian nesting success, it is often of interest to estimate st age-specific daily survival probabilities of nests. When data can be partit ioned by nesting stage (e.g., incubation stage, nestling stage), piecewise application of the Mayfield method or Johnson's method is appropriate. Howe ver, when the data contain nests where the transition From one stage to the next occurred during the interval between visits, piecewise approaches are inappropriate. In this payer, I present a model that allows joint estimati on of stage-specific daily survival probabilities even when the time of tra nsition between stages is unknown. The model allows interval lengths betwee n visits to nests to vary, and the exact time of failure of nests does not need to be known. The performance of the model at various sample sizes and interval lengths between visits was investigated using Monte Carlo simulati ons, and it was found that the: model performed quite well: bias was small and confidence-interval coverage was at the nominal 95% rate. A SAS program for obtaining maximum likelihood estimates of parameters, and their standa rd errors, is provided in the Appendix.