A comparative analysis of population estimation methods for a burrow-nesting seabird: a novel ground-count method and closed population capture-recapture modelling

Abstract

Spatial variation in nesting patterns can cause variation in population size estimates. This thesis research shows that more accurate estimates can be made of population sizes of breeding burrow-nesting seabirds by mapping Bonin Petrel (Pterodroma hypoleuca) nesting colonies into low, medium, and high burrow densities and then randomly conducting burrow density and occupancy surveys, as compared to more traditional censusing methods. Results from closed population modelling, using the Program MARK, indicate that capture-recapture studies may be useful in estimating the total population size of Bonin Petrels. Capture-recapture studies are more time/cost-effective than ground-count studies, are less harmful to the study species, and can estimate both breeding and total population sizes of any burrow-nesting seabird species worldwide. Support for distinguishing breeding females from breeding males and non-breeding individuals through cloacal size is provided, and the importance of habitat (and Verbesina encelioides, an invasive species) to Bonin Petrel nesting patterns is discussed.