Hello everyone,
I am facing a problem that I cannot solve at the moment. I want to calculate a population size (small mammals) and my choice fell on the Jolly-Seber model. Everything is clear as far as the calculation is concerned. My problem at the moment is the data. The season is from April to October. During this time, traps are set and nest boxes are checked at undefined intervals (but the nest boxes are always checked monthly). The animals are tagged and released. My data range from 2019 to 2022.
The problem at the moment is the data base. Do I calculate the population size from survey to survey, e.g. April 2019 to May 2019, then from May to June, from June to July and so on, or can I calculate from year to year? Then I could look at how many individuals were captured and tagged in 2019, how many of those individuals were recaptured in 2020, how many were added in 2020 and so on until 2022.
Then I could theoretically calculate the population size from year to year or based on 2019 (which individuals from 2019 were also captured in 2022?).
My question is whether this calculation is possible from year to year or whether I have to calculate from session to session within a season? Between the seasons is winter, during which the animals hibernate. An individual caught in 2019 could be caught again in 2022!
Calculating from year to year seems to make more sense to me and is much more bearable, especially when preparing the data - although this plays a subordinate role.
Thanks in advance.
Cheers
Hi,
Some good references;
Measuring Abundance:Methods for the Estimation of Population Size and Species Richness by Graham J. G. Upton, 2020
Steven C. Amstrup, Trent L. McDonald, Bryan F. J. Manly, "Handbook of Capture-Recapture Analysis" | 2005
Handbook of capture–recapture analysis / edited by Steven C. Amstrup, Trent L. McDonald, and Bryan F. J. Manly.
Perhaps calculate population size both ways -- estimates from monthly data, estimates from annual data. Then one can see the variation of the estimates, reflecting either sampling limitations, variations in the animals' behavior, or actual population variations.
The Jolly-Seber model is used to estimate population size from season to season. It is a capture-recapture method that is used to estimate the size of a population based on the number of individuals that are captured and marked in one season and then recaptured in another season.
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