seasonal occupancy (eps=1-gam) and detection model

[michael.hudson1989]

Hi,

I am trying to run a seasonal occupancy (eps=1-gam) and detection model however presence is only displaying a single phi estimate i.e. initial occupancy (psi1) rather than seasonal i.e. psi1, psi2, psi3 and psi4 as in all the other seasonal occupancy models I can run which all come up correctly (I have successfully run a seasonal occupancy, colonisation and detection model). Any suggestions?

Many thanks,

Mike

[jhines]

Mike,

If (1-extinction)=colonization, then occupancy in time t+1 = colonization in time t. Here's how it works:

psi(2) = psi(1)*(1-eps(1))+(1-psi(1))*gam(1).

Since (1-esp(i))=gam(i),

psi(2) = psi(1)*gam(1)+(1-psi(1))*gam(1), which reduces to:

psi(2) = gam(1).

Changing the subscripts, you get any psi(t+1) = gam(t). So, you don't need parameters for any psi's except the first one. Occupancy is changing over time, but it is equal to the colonization rate.

Jim

[michael.hudson1989]

Many thanks,

Obvious now!

Mike