Extrinsic and intrinsic factors drive the timing of gestation and reproductive success of Scandinavian brown bears

• Published in: Frontiers in Ecology and Evolution
• Main Authors: Lemière, Lucie, Thiel, Alexandra, Fuchs, Boris, Gilot-Fromont, Emmanuelle, Hertel, Anne G., Friebe, Andrea, Kindberg, Jonas, Støen, Ole-Gunnar, Arnemo, Jon Martin, Evans, Alina L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: biologging; embryonic diapause; reproductive phenology; reproductive success; Ursus arctos; VDP::Zoologiske og botaniske fag: 480; VDP::Zoology and botany: 480; Fuchs
• Online Access: https://hdl.handle.net/11250/3036896; https://doi.org/10.3389/fevo.2022.1045331

© 2022 Lemière, Thiel, Fuchs, Gilot-Fromont, Hertel, Friebe, Kindberg, Støen, Arnemo and Evans. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Climate change is altering the reproductive phenology of many organisms, but the factors that influence the timing of gestation in ursids are still poorly understood. Higher temperatures in spring are already causing an earlier den exit in some brown bear populations, and a temporal mismatch between hibernation and reproduction could have dramatic consequences for reproductive success. Therefore, understanding the factors that control the timing of these events is important to forecast the consequences of climate change on population growth rates. In this study, we used abdominal temperature loggers and GPS collars with acceleration sensors on 23 free-ranging pregnant female brown bears living in two areas in Sweden (61◦N and 67◦N latitude) to pinpoint hibernation and reproductive events. We investigated how intrinsic and extrinsic factors influence the termination of embryonic diapause and parturition, as well as their impact on reproductive success. The termination of embryonic diapause was later in the northern area compared to the southern area and occurred earlier when ambient temperature at den entry was higher in both areas. In the southern area, young adults (i.e., females = 7 years old) had a delayed parturition when bilberry abundance was low the year of mating. Additionally, young adults had a lower reproductive success than adults and their probability to reproduce successfully was dependent on bilberry abundance, whereas adult females were not affected by this ...