Number of surveys and GENPRES error

[rk1177]

Hi,

We are looking to use multi-season occupancy models to monitor an endangered squirrel population within various habitat types. We would like to estimate occupancy for each habitat type using remote cameras and observe changes in occupancy from year to year. Preliminary data shows that occupancy varies between habitat types (from 0.4 to 1.0) and that the species is reasonably detectable (p = 0.3 to 0.7).

We have placed 5 cameras in each habitat type and we believe this is the maximum number of locations possible if independence is to be maintained. We would like to obtain the most unbiased and accurate estimates of occupancy as possible, and are trying to determine the optimal number of survey days to do so. I have been using GENPRES to simulate the effect of various numbers of survey days on occupancy estimates, but the program gives me an error message when I attempt to go above 17 surveys (Error – No HIST = specified). Has anyone encountered this error before?

Given the rough estimates of occupancy and detection probability for this species, does anyone have a sense of how many surveys would be optimal to obtain the most unbiased estimates and to detect occupancy trends?

Thanks,
Becky