Influence of maternity penning on the success and timing of parturition by mountain caribou (Rangifer tarandus caribou)

Abstract

Invasive conservation actions that require the capture and handling of individual animals are common, but the implications for both survival and reproduction are often not studied. Across North America, most populations of woodland caribou ( Rangifer tarandus caribou (Gmelin, 1788)) are Threatened or Endangered. Maternity penning, where pregnant females are held in an enclosure until the calf is less vulnerable to predation, is one conservation action that is designed to increase population growth. Few studies have reported the influence of maternity penning on the occurrence or timing of parturition and the implications for reproduction. We quantified parturition success and dates of penned and free-ranging caribou within the Klinse-Za population of caribou found across east-central British Columbia, Canada. Parturition dates were identified using daily observations for penned caribou ( n = 41) and estimated dates for free-ranging caribou ( n = 27) generated using statistical modelling of GPS collar data. We related parturition outcomes to a range of ecological and environmental variables. We found that the occurrence and date of parturition did not differ between penned and free-ranging caribou. For all monitored animals there was an earlier calving date during years of higher snowfall and warmer winter weather. Our results suggested that maternity penning, a potentially invasive conservation action, did not increase or decrease the probability or date of parturition for this study population.