HAS THE PORCUPINE POPULATION WANED IN BRITISH COLUMBIA? TRENDS IN QUESTIONNAIRES AND ROAD-MORTALITY DATA

Abstract

The Porcupine (Erethizon dorsatum) is considered ‘secure' in British Columbia, but as for many species with this status, there is a notable absence of quantitative data on population trends. In view of this issue, concerns about declining numbers of the species prompted us to conduct a preliminary survey using a questionnaire in 2005, targeting various sectors of government, industry, and the public across British Columbia. Ten years later, we distributed a nearly identical questionnaire to allow comparisons and identify changes over the intervening decade. Respondents in both surveys reported a perceived decline in Porcupine sightings, although there was no significant change in the overall combined level of concern of respondents for the population between the 2 surveys; however, the proportion of respondents reporting that they were “very” concerned about the population trend over time did increase from the 2005 to 2015 survey. We augmented this information with data from road-mortality datasets collected by the provincial government and Parks Canada. Both datasets provided further support for a decrease in Porcupine abundance in the province. We discuss possible causes for this apparent decline, including natural population dynamics and the impact of climatic variation on predator-prey dyads. Overall, a comprehensive field study on Porcupine populations is needed to accurately assess the status of this species in British Columbia to corroborate our survey results suggesting a decline.