Individual covariates – nest survival

[Rebecca]

Hi all,

I have a query regarding the use of individual covariates that change over time using the nest survival model. The covariate I’m interested in is water depth. Nests are distributed across plots with differing water depths that change daily. I was going to use an approach similar to the example “observer effects on DSR” in the online MARK manual. Instead of using 89 individual covariates coding for whether a nest was checked or not I would use 89 (or the length of my observation period) individual covariates for each daily water level.

example
day1 day2 day3 day4…………..day89
Nest1 0.12 0.13 0.33 0.15 …………..0.18
Nest2 0.14 0.14 0.41 0.24… ………0.80

My question is should I use a 0 until the nest enters the observation period, and zeros once it fails/succeeds? Or doesn't matter?

Example Nest1 found on day 3 and only observed for 4 days.
Nest1 0 0 0.33 0.15 0.18 0.22 0 0 0 0

thank you
Rebecca