Nest Survival Issue

questions concerning analysis/theory using program MARK

Nest Survival Issue

Postby elise3b » Thu Jan 14, 2021 3:00 pm

I have a long-term data set that I last analyzed using Version 7.2 of Mark. I have an input files for estimating total mortality in a bighorn sheep population, and a second one that looks at cause-specific morality from cougar predation. In the second case, I replace the column where 1= Dead, with 1 = Killed by a cougar. This results in instances where the live/dead =0 but the last 2 times are not equal (because they died from something else). Version 7.2 (and earlier) seems to just ignore this anomaly as no warning messages were received and the mortality rates calculated were in line with % of radiocallar mortalities. After a hiatus, I took up this data set again and I recently downloaded the recent version of Mark and I am now getting errors and different results. The analysis still works fine if I use Version 7.2 so I think the issue is in the way the different versions are handling this anomaly. I have a very large data set at this point so making changes will be both time consuming and I could introduce mistakes along the way. My question is, would it be best to 1) keep using Version 7.2, or 2) bite the bullet and make the changes to the data set? If the latter, would I censor the animals that died from "other causes" and set the dates equal to the last live date? Thanks for your help.
elise3b
 
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Re: Nest Survival Issue

Postby Jochen » Fri Jan 15, 2021 7:10 am

Hi,

it seems to me you should have censored the animals that died from "other causes" already in your previous analysis, so it ist a good time to do it now.
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Re: Nest Survival Issue

Postby elise3b » Fri Jan 15, 2021 8:53 pm

Thanks for the advice, I appreciate it!
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