Boreal caribou: Science to inform critical habitat idenfication in Canada

Background/Question/Methods

The Woodland Caribou (Rangifer tarandus caribou), Boreal Population, is listed as a species Threatened with the risk of extinction under the Canadian Species at Risk Act (SARA) in 2001. The Minister of the Environment must prepare a Recovery Strategy for this species under SARA that includes an identification of its critical habitat where possible. In 2008, Environment Canada published a report that provided a scientifically defensible description of critical habitat for boreal caribou. The critical habitat description assessed whether the current conditions of each of the 57 boreal caribou ranges in Canada where sufficient to allow populations to survive over the long-term. The range assessment was based on available population information and an analysis quantifying the negative effects of disturbance (fire and buffered human disturbance) on caribou demography. We describe a number of new analyses undertaken since 2008 to refine the description of critical habitat for the species’ Recovery Strategy. These analyses focused on quantifying the zone of influence of different disturbance types, defined as habitats that are functionally impaired for boreal caribou due to increased predation and sensory disturbance, and the configuration of disturbance on the assessment of current range conditions.  

Results/Conclusions

Our analyses indicated that the zone of influence for anthropogenic disturbance was adequately captured by a 500 m buffer radius at a national scale. The predictive power of the demographic model tested was also enhanced by buffering fire. In general, metrics quantifying the configuration of disturbance did little to improve model performance after controlling for the total amount of disturbance. This result appeared to be in part because buffering disturbance captured some basic information about the effects of the configuration of disturbance on boreal caribou demography such that buffering has less of an impact on estimates of total disturbance in areas where disturbance is aggregated compared to areas where disturbance is dispersed. In conclusion, our model appears to be a useful starting point for assessing current range condition, particularly for areas in Canada where there is little information on boreal caribou that can be enhanced with more regional specific information as it becomes available.