Wildlife Management and Climate Change: How to Adapt Harvest Rates of Wild Turkey According to Extreme Weather Events.

Abstract

Climate change is forcing many species to shift their distribution north. Managing these expanding species is a challenge because the factors that influence population dynamics vary with weather. The challenge is even greater for game specie, as other human factors must be considered. The wild turkey naturally expanded its distribution northward into southern Quebec, without humans transplanting turkeys from other regions. However, the northern expansion is currently limited by extreme weather events. We used matrix modelling to explore the respective and interactive effects of weather and harvest levels on demographic parameters of three populations at different expansion stages but all at the northern edge of the species distribution. Our results suggest that populations at the expansion front (fast-paced life history) can sustain higher hunting rates than well-established populations (slow-paced life history), but that the proportion of adult males declines more rapidly in response to a given level of harvest. Furthermore, populations at the expansion front under harsh to extreme conditions could not tolerate any level of harvest. Finally, fall hunting had the greatest influence on population dynamics mainly because harvesting of all females is permitted, while spring hunting is restricted to bearded birds only (<1% of turkeys harvested in spring are bearded hen). Optimal hunting regimes for populations at the limit of their distribution vary with weather and expansion stages. A conservative solution would be to allow fall hunting only in well-established populations, but adaptive management where fall harvest at the expansion front would be implemented during more mild winters. Our model approach is relatable to the very many populations currently expanding poleward in response to climate change by considering different adaptive management policies in established and expanding populations.