Evaluation of Maternal Penning to Improve Calf Survival in the Chisana Caribou Herd

• Published in: Wildlife Monographs
• Main Authors: Adams, Layne G., Farnell, Richard, Oakley, Michelle P., Jung, Thomas S., Larocque, Lorne L., Lortie, Grant M., Mclelland, Jamie, Reid, Mason E., Roffler, Gretchen H., Russell, Don E.
• Other Authors: U.S. Fish and Wildlife Service, U.S. Geological Survey, National Park Service
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Rangifer tarandus; Alaska; Yukon
• Online Access: http://dx.doi.org/10.1002/wmon.1044; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fwmon.1044; https://onlinelibrary.wiley.com/doi/pdf/10.1002/wmon.1044; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/wmon.1044; https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/wmon.1044; https://wildlife.onlinelibrary.wiley.com/doi/pdf/10.1002/wmon.1044

ABSTRACT Predation is a major limiting factor for most small sedentary caribou ( Rangifer tarandus ) populations, particularly those that are threatened or endangered across the southern extent of the species’ range. Thus, reducing predation impacts is often a management goal for improving the status of small caribou populations, and lethal predator removal is the primary approach that has been applied. Given that predator control programs are often contentious, other management options that can garner broader public acceptance need to be considered. Substantial calf losses to predation in the few weeks following birth are common for these small caribou populations. Therefore, we employed a novel experimental approach of maternal penning with the goal of reducing early calf mortality in the Chisana Caribou Herd, a declining population in southwest Yukon and adjacent Alaska thought to number around 300 individuals. Maternal penning entailed temporarily holding pregnant females on their native range in a large pen secure from predators from late March through the initial weeks of calf rearing to mid‐June. During 2003–2006, we conducted 4 annual penning trials with 17–50 pregnant females each year ( n = 146 total), assessed survival of calves born in the pens, and evaluated survival and nutritional effects of penning for females that were held. We also investigated the herd's population dynamics during 2003–2008 to determine effects of maternal penning on calf recruitment and population growth. In addition to information gained during maternal penning, we determined natality and survival patterns via radiotelemetry, conducted autumn age‐sex composition surveys each year, and censused the population in mid‐October 2003, 2005, and 2007. Based on our penning trials and demographic investigations, we used simulation models to evaluate the effects of maternal penning relative to a population's inherent growth rate (finite rate of increase [λ] without maternal penning) and penning effort (proportion of calves born in ...