Censoring individuals within Nest Survival Module

[djohns]

Hello,

I am interested if it is possible to censor "missing" individuals during ragged telemetry using the nest survival module?

I am studying juvenile survival rates in a precocial bird in which we marked the attending female prior to nest hatch and monitored juvenile survival weekly to brood fledge. One of the assumptions for the analysis is that if the attending female disappears (via radio loss, mortality, emigration) prior to fledging then the offspring are considered dead (fate=1). My question arises on how to best represent these cases within the nest survival framework.

For example: A bird is found on day 1, is last seen alive and young are counted on day 14 but disappears prior to the next count on day 21. Typically the encounter history would read; found=1, last present=14, last checked=14, fate =1. However, this would technically be an error since the bird cannot be present and dead in the same encounter occasion. Could one in theory censor those records only up to day 14 and indicate the bird was alive (i.e. found=1, last present =14, last alive =14, fate=0)? Will this bias survival estimates?

This case could also apply when incomplete counts have been made. Ideally in that case it is probably better to model survival using the Marked Young module and be able to account for periods where no count has been made and get estimates of detection. However from my understanding the young survival module works best when the number of offspring per brood is < 5 (will not work for our species) nor can Bootstrap methods be employed to estimate overdispersion.

Thanks for your consideration!

[Jochen]

Hi,

In your example, if your female bird is known (!) to be dead/emigrated before fledging it must be
found=1, last present=14, last checked=21, fate =1

If the female lost/shed its transmitter (or if your last check was after the expected fledging date) and chick fate is therefore uncertain you could use censoring as described.