Appropriate model selection

[Eldad Elron]

Hello All,

I am wondering if some of you can suggest which MARK modeling approach we should select. We have three years of mark-recapture data (PIT tags) of green toads from five study sites. We are interested in the survivorship from year-to-year and the number of animals in the population (recapture).

Each year (trapping session), sampling lasted for about 5 months (until all individuals disappeared to their summer shelters), with unequal number of capture occasions (about 10-15 trapping events each year), and unequal time intervals between capture occasions.

I'm not sure what is important for survival but we have the following covariate: sex, body length (SVL) and weight. We can also try to incorporate habitat type (or disturbance).

From our data we assume that emigration and immigration happened rarely during the breeding season and between years but we can't ignore it, so we need to use an open population model. What is the appropriate MARK model design that we should use accordingly to the above data? It sounds like we may need to use a robust design in MARK and we have no experience with it.

Thanks in advance,

Eldad
[/b][/quote]