two-species analysis of grid capture data

[jlehmkuhl]

A few questions on building 2-species occupancy models. I am studying habitat use and interactions of 2 chipmunk species (Neotamias amoenus, N. townsendii). They are parapatric species, and N. townsendii is a strong interference competitor of N. amoenus.

Mark-recapture analysis quantified demography in 12 stands representing 3 cover types. Each stand was sampled over an 8-day trap period on 64 grid stations (2 traps each station) for each of 4 years.

Several occupancy model questions: (1) I am uncertain what should be the occupancy "site" or sample unit – the grid point or the stand? If the grid point, then would stand be a covariate? (2) There are two scales of visits, within-sessions and years - how to deal with it? (3) The 2-species model can be done only in PRESENCE, but not in MARK, correct?

Another analysis option is to model N. amoenus demography using N. townsendii abundance as a covariate in MARK. Suggestions on either approach, or other methods, are welcome.

[darryl]

The big questions that only you can answer is at what scale do you expect biologically interesting interactions to occur, and how exactly would you like to quantify that.