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Empirical validation of closed population abundance estimates and spatially explicit density estimates using a censused population of North American red squirrels Open Access


Other title
program DENSITY
empirical validation
closed population abundance estimation
Kluane Red Squirrel Project
program MARK
North American red squirrel
spatially explicit capture-recapture
Type of item
Degree grantor
University of Alberta
Author or creator
Van Katwyk, Kristin E
Supervisor and department
Boutin, Stan (Biological Sciences)
Examining committee member and department
Derocher, Andrew (Biological Sciences)
Bayne, Erin (Biological Sciences)
Department of Biological Sciences
Date accepted
Graduation date
Master of Science
Degree level
Capture-mark-recapture (CMR) data is widely used to estimate a range of population parameters including abundance and density. Closed population estimators have gained wide acceptance and have become increasingly sophisticated. More recently, spatially explicit capture-recapture (SECR) models implemented have gained popularity. Although model accuracy has been tested via simulation studies there have been few empirical tests of either method. I took advantage of a fully enumerated population of red squirrels (Tamiasciurus hudsonicus) to test the accuracy of closed population abundance estimator and the maximum likelihood SECR density estimator. I found abundance estimates were positively biased by 45%, largely due to trapping grid edge effects. Adjusting for edge effects via the boundary strip method decreased bias to -22%. With the addition of inter-trap movements, SECR models produced density estimates that were negatively biased by only 4.6%. These empirical validations support the use of SECR models for density estimates or derived population abundance.
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