Accounting for translocated individuals

[Melissa Taylor]

Morning,

I'm going to be doing some analyses on 10 years of cage trapping data in a large area that includes translocation harvest trapping throughout (some of which I'll have to remove from the analysis because not all traps have location data). So the plan is to use multi session openSCR, which I've already got code/advice for from someone. 

My question is, is there a way to explicitly tell the model when individuals have been removed between/during a session? Or would I just have to interpret the results keeping the known change in mind?

I swear I've read somewhere that it could be done but can't find it again. Though it might have been for spatial mark resight models?

Thank you so much in advance!

Mel

[Murray Efford]

Hello Mel

Most likely your harvest trapping can be treated as  'loss on capture' which is routinely allowed in 'secr' and 'openCR'. Removed animals are indicated by placing a minus sign before the number of the last occasion they were caught.

The _Microtus_ builtin dataset of openCR includes such losses, shown by the difference between n (number caught) and R (number released) in this table:

JS.counts(microtusCH)
    n   R  m  r z
1 108 105  0 89 0
2 127 121 84 76 5
3 102 101 73 68 8
4 103 102 73 63 3
5 102 100 61 84 5
6 149 148 89  0 0

So you could play with that to see how it works. As you imply, this gets a bit tricky if harvest happens outside structured trapping sessions.

Murray

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[Melissa Taylor]

Hi Murray,

Thank you so much! I'll have a go with that and look at the Microtis data 😊

Thank you again!

Mel