Specifying Caribou Migratory Behaviours to Identify and Preserve Intraspecies Diversity

Organization
Resource Type
Authors
Jessica L. Theoret
Contacts
Date:
2020

Abstract: 

Preserving intraspecies diversity, a fundamental conservation goal, strengthens species adaptability. Across most of their range, caribou are declining, with some recent population extirpations. Migratory or sedentary movement behaviours are considered adaptive relative to local ecological conditions of Barren-ground and Woodland Caribou populations (respectively). In addition, these behaviours may be genetically influenced. As populations decline and are lost, local characteristics, including movement ecology and genetic traits (or their links) that may be adaptive, are also at risk of disappearing. In this Thesis, I describe the prevalence of migratory, resident, and other seasonal movement behaviours for Barren-ground and Woodland Caribou in northern and western Canada. I exemplify that caribou behaviour is diverse and complex, requiring a combination of methods to categorize, and I challenge traditional distinctions between, and binary categorization of, migratory and resident behaviour. I also develop an equation for quantifying between-year individual behavioural plasticity to estimate how flexible caribou can be in their movement behaviour. Finally, I assess the potential for reproductive isolation between migratory versus non-migratory caribou in populations where both seasonal behaviours co-occur. I therefore determine the location of, and separation between, migratory and non-migratory individuals during the rutting season to evaluate if individuals exhibiting the same movement behaviour are associated with one another during the period of genetic exchange. Despite the common description of Woodland Caribou as primarily non-migratory, migratory behaviour was found to occur widely in Woodland Caribou populations. Additionally, individuals were flexible in their migratory behaviours between years. Populations may therefore be more behaviourally diverse and perhaps behaviourally adaptable than previously thought. However, I also found that migratory and non-migratory caribou could be separate during the rutting season, indicating potential for reproductive isolation. From these results, correlations of seasonal movement behaviours with environmental conditions and with genetic traits could be determined to evaluate if caribou respond to the environment plastically or if instead, they are limited by their genes. Specifying seasonal migratory behaviours, evaluating between-year behavioural plasticity, and testing for genetic predispositions for seasonal movement patterns may help refine conservation and management strategies to aid caribou recovery.