The development of a habitat suitability index model for burrowing owls in southwestern Manitoba and southeastern Saskatchewan

Abstract

Recent efforts aimed at sustaining burrowing owl (' Athene cunicularia') populations in Manitoba have been unsuccessful, and the species is now verging upon extirpation from the province. Degradation of suitable habitat may be a major contributor to the decline of the burrowing owl population, although specific causes remain unknown. An HSI model was developed for use in determining the suitability of burrowing owl nesting habitat in southwestern Manitoba and southeastern Saskatchewan. Model parameters were obtained using a modified Delphi technique to solicit expert opinion as population sizes from which to sample were insufficient and quantitative, geographically specific habitat requirements of the species were absent from published literature. Burrowing owl experts from southwestern Manitoba and southeastern Saskatchewan identified 19 habitat components required by burrowing owls, 9 of which were determined to be critical in the identification of burrowing owl habitat suitability and were identified as model parameters. An interactive, adaptive learning approach was used in model development, iteratively refining the model until acceptable levels of accuracy and robustness were achieved. The resulting HSI model was verified using an interactive computer program then validated using known optimal burrowing owl habitat in Saskatchewan and historic burrowing owl breeding sites in Manitoba. Application of the burrowing owl HSI model on Manitoba's historic burrowing owl breeding sites determined that habitat suitability is slightly sub-optimal relative to burrowing owl habitat available in southeastern Saskatchewan due to a presence of tall vegetation at nest burrows. The suitability of burrowing owl breeding habitat in southwestern Manitoba could therefore be improved if grassland management efforts were directed toward limiting vegetation height proximal to the nest burrow.