How to deal with inconsistent recapture events

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How to deal with inconsistent recapture events

Postby bootzies » Fri Jul 08, 2016 12:09 am

Hello all,

I have a data set of chick banding and adult recapture for a seabird colony. The whole data set covers a long period (over 20-years), during which chicks were banded in most years. However, adults were only recaptured in a few years (including in 2015). The reason for this is that chick banding only takes 1-day of field work and can be done by 1 or 2 people, whereas adult recapture takes nearly a week and requires more people. Unfortunately time and money limitations have meant that adult recaps could not be undertaken very often.

I know that I can change the time intervals between occasions when setting up my models. But I am not sure how to deal with data where there are occasions when marking occurred, but recapture effort did not. I don't want to exclude those occasions from the data set. But if I don't somehow 'tell the model' that recapture effort wasn't expended at each occasion, I feel like this will affect the model estimates (perhaps I am wrong?). Should I fix the recapture probability to 0 for the years when we didn't attempt to catch adults?

It's not directly relevant to my question, but in case it is of interest or makes a difference to specific advice on this issue, I use RMark for my analyses.

Any advice would be much appreciated.

Thanks,

Alice
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Re: How to deal with inconsistent recapture events

Postby jlaake » Mon Jul 11, 2016 3:43 pm

I presume you are using CJS or something similar.If so then yes that is exactly what you do. Set p=0 for those occasions at which there were releases (of chicks) but no recapture effort.

--jeff
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Re: How to deal with inconsistent recapture events

Postby bootzies » Tue Jul 12, 2016 9:07 pm

Yes that's correct, I am using a CJS.
Thanks very much for your helpful response.
Alice
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