Colonization definition

[ryan pienaar]

Hello,

I am using a dynamic occupancy model for the first time and just want to understand the interpretation properly.

I created my candidate models and my best model based on AIC used

psi ~ 1

gamma ~ years

epsilon ~ Forest

p ~ Forest*Fire

Years refers to years post-fire, and I have it as numeric, ranging between 2 and 5. Forest is a factor with 3 levels, and Fire is a factor with 2 levels.

When I predict colonization I get

Est                  SE                    LinComb      Int   Years
0.7027421 0.1468306 0.8603896 1 3
0.3773687 0.2016311 -0.5007320 1 4
0.1344871 0.1682102 -1.8618536 1 5

What I want to make sure I understand correctly is, colonization is defined as the probability that a site unoccupied at primary sampling period t is occupied by the species at t+1 (colonization). Is the colonization probability at t+2 calculated using the unoccupied sites at the primary sampling period t or at t+1? Because if it's defined off of t, my results are impossible, but it would make sense if it's t+1.

Thank you

[Marc Kery]

Dear Ryan

fortunately, there is order in the universe 😉 This is a Markov model, which means that the state at time t+1 is a function of the two parameters gamma and epsilon, and of the state at time t, for every t until t-1. That is, there is a "one-time-step-back dependency".

Best regards  – Marc

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[ryan pienaar]

Great! Thank you for the help!