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Population development and recapture probabilities

Number of male individuals as estimated by the Jolly-Seber open population model.

In this population, only one generation was found. Most adult-recruitment took place in late-July, and the very last nymph was observed on the 14th of August. Survival was high, allowing the population to persist until mid-October.

Recapture probabilities were low, meaning that marked individuals known to be alive during a certain visit were not easy to recapture.
 

Simulated monitoring

Accuracy of population size estimates from simulated monitoring, where the main data set was downsampled to only two (circles, Petersen's method) or three (circles, Schumacher-Eschmeyer) visits. A value of one (horizontal line) would mean the estimate is the same as the best estimate based on the whole data set. A value of four means the estimate overestimates the population size by a factor of four.

Accuracy did not seem to depend on the time interval used. However, high recapture rates were vital for accuracy.

Habitat preferences

Male densities (observations / km searched) as predicted by a generalised linear model when varying the number of small junipers and area of cell covered by felled trees. All other habitat characteristics kept at median values.

I found that even when accounting for known preferences such as a southern aspect and the lack of tree cover, male individuals were found more often in cells with larger amounts of small junipers and felled trees.


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Last updated: 06/01/18