Hello!
I'm relatively new to MARK, started using it for survival and abundance estimates using a robust design Poisson-log-normal mixed-effects mark–resight (RDPNE) model through RMARK
However, there's something I'm having trouble with, which is using these data along age structure.
Let me explain:
I have camera trap data of an agouti population, with a sample of the population that is marked (both adults and juveniles). I also have unmarked registers of both adult and juvenile individuals.
In concern to 'Phi', so far so good. I'm supposed to be able to modify the PIMs to reflect an age effect.
However, I'd like to model the effect of age on the resighting rate (alpha) as well, and this parameter doesn't have a release-cohort strucutre, so I'm having trouble grasping how to model the effect of age on it.
Reading the RMARK help file, I've found a reference to emulating cohort structure by creating a group variable 'cohort' and since RPDNE asks for the
number of 'Unmarked Seen' for each interval*group, it makes no sense use a cohort grouping variable of Unmarked individuals (because the cohort is 'time marked')
Probably there's some obvious solution for this, but I've been brewing this thing over in my head for days and still couldn't figure anything out.
Did anybody run into a similar issue, or otherwise have any ideas on how to get around this?
Thanks in advance!