Dear all,
I am trying to run a multi-season model with Unmarked. There are a total of 16 sites, surveyed 9 days each for 4 years (some of the sites were not surveyed all the years and I inserted NAs for the corresponding dates).
It worked fine until I added the data for the last season (2021). Then, when I try to run a model selection for detection parameter
fmx1.1<-colext(~1,~year-1,~year-
1,~year+date+rain+air+hour+cow+ROCK+bush+log+veg,umf_RT)
it returns an error message: "
Error in optim(starts, nll, method = method, hessian = getHessian, ...) : non-finite finite-difference value [14]"
Could anyone provide any ideas?
Interestingly (or worringly), when I tried the same code for another species (same covariates, only different presence/absence values) it runs perfectly fine.
Best,
Michele Chiacchio