I am working with camera trap data of the rodent Cuniculus paca. I have five sampling months, each one divided in five secondary intervals. I am using the closed population model with heterogeneity (FullHet), through RMark. I am considering each sampling month a separate group.
When I run the simplest model (p and c are equal and constant, f0 varies between groups), I get bad estimates for the first group/sampling month. Which is strange, because it is the interval with most recaptures. If it was the other way around (the first month was the only one with an estimable N) I would understand, but this got me really confused. Does anyone know what could be happening?
Input data
- Code: Select all
ch group freq
00010 1 1
01000 1 4
01001 1 2
11010 1 2
11111 1 2
00010 2 2
01000 2 2
10110 2 1
00010 3 2
00100 3 2
01000 3 3
10000 3 1
10111 3 1
11011 3 1
00111 4 1
01000 4 1
10000 4 4
11110 4 1
00001 5 2
00010 5 2
00100 5 1
01000 5 1
01101 5 1
10000 5 1
Code
- Code: Select all
test<-RMark::mark (paca.data,paca.ddl,
model.parameters=list(
pi=list(formula=~1),
p=list(formula=~1,share=T),
f0=list(formula=~group)
),
options="SIMANNEAL",
threads=-1)
Results:
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> test $results$derived
$`N Population Size`
estimate se lcl ucl
1 11.000003 0.0000000 11.000003 11.00000
2 5.091734 0.9248441 5.001351 11.22845
3 11.937425 1.9811715 10.369055 20.17090
4 9.478182 2.5067593 7.478165 19.84365
5 13.112574 4.5145513 9.154381 30.64280
> test$results$beta
estimate se lcl ucl
pi:(Intercept) -16.543780 0.0000000 -16.5437800 -16.5437800
p:(Intercept) 0.067066 0.3567744 -0.6322119 0.7663440
p:group -0.341798 0.1364858 -0.6093101 -0.0742859
f0:(Intercept) -12.603484 0.0000000 -12.6034840 -12.6034840
f0:group2 10.214624 0.0000000 10.2146240 10.2146240
f0:group3 13.264843 0.0000000 13.2648430 13.2648430
f0:group4 13.511009 0.0000000 13.5110090 13.5110090
f0:group5 14.235187 0.0000000 14.2351870 14.2351870
Thank you in advance!