A Distribution Free Nesting Survival Model

In nesting survival studies nests are not found until after incubation has begun and therefore nests which fail are of unknown age while nests which succeed can be aged afterwards. Typically ornithologists have considered the survival time to be from first encounter and have used the Mayfield method (Mayfield 1961, 1975) or variations of it. Here we consider a new discrete survival model which allows estimation of the survival distribution from the time of nest initiation. Nests which succeed are used to estimate the proportions of nests being found (encountered) in each time interval. Assuming that these encounter probabilities also apply to the nests which fail it is possible to estimate a series of discrete failure time probabilities for all the nests. We present maximum likelihood estimators and computer programs to calculate them. Our methodology is illustrated by a real example on mourning doves. We conclude with some suggestions for future research.