title: Predicting climate change impacts on polar bear litter size.
abstract: Predicting the ecological impacts of climate warming is critical for species conservation. Incorporating future warming into population models, however, is challenging because reproduction and survival cannot be measured for yet unobserved environmental conditions. In this study, we use mechanistic energy budget models and data obtainable under current conditions to predict polar bear litter size under future conditions. In western Hudson Bay, we predict climate warming-induced litter size declines that jeopardize population viability: ∼28% of pregnant females failed to reproduce for energetic reasons during the early 1990s, but 40-73% could fail if spring sea ice break-up occurs 1 month earlier than during the 1990s, and 55-100% if break-up occurs 2 months earlier. Simultaneously, mean litter size would decrease by 22-67% and 44-100%, respectively. The expected timeline for these declines varies with climate-model-specific sea ice predictions. Similar litter size declines may occur in over one-third of the global polar bear population.
authors.affiliation: Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2G1. pmolnar@ualberta.ca
authors.forename: Péter K
authors.initials: PK
authors.lastname: Molnár
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Derocher
authors.forename: Tin
authors.initials: T
authors.lastname: Klanjscek
authors.forename: Mark A
authors.initials: MA
authors.lastname: Lewis
mesh_terms: D000818:Animals; D001824:Body Constitution / Q000502:physiology; D057231:Climate Change; D003247:Conservation of Natural Resources / Q000379:methods*; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D008098:Litter Size / Q000502:physiology*; D016015:Logistic Models; D008350:Manitoba; D008954:Models, Biological; D011247:Pregnancy; D001503:Ursidae / Q000502:physiology*