Life history consequences of climate change in hibernating mammals: A review

Climatic shifts to warmer and often drier conditions are challenging
terrestrial species worldwide. These shifts are occurring more rapidly at
higher elevations and latitudes, likely causing disproportionate effects
to mammalian hibernators there. While there is some information about how
these species’ ranges are responding to climatic shifts, we lack an
understanding of how climate components are affecting species’ life
history variation, which is key to individual success and population-level
resilience. We reviewed the literature to identify the direction of life
history responses to climate change in mammalian hibernators along three
axes: latitudinal, elevational, and temporal. We found 39 studies
involving 27 species that reported climate effects on our four target life
history traits – phenology, body mass/condition and growth, reproduction,
and survival. We found warmer temperatures are advancing hibernator
phenology and increasing reproductive success. By contrast, warming and
drying trends are having uncertain effects on body condition, and complex
effects on survival - depending on season, age class, latitude, and
elevation. We found no pattern of significant climate-trait outcomes by
duration or decade of study. More research on drought conditions -
particularly in relation to resource availability - would help inform
hibernator susceptibility to increased drying trends expected to intensify
globally. Notably, our results are highly biased towards small mammal
hibernators in Northern hemisphere alpine/mountain ecosystems, with few
long-term studies conducted on Southern hemisphere hibernators.This review
highlights that phenological shifts constitute one of the most obvious
consequences of climate change, yet, the timing of life history events
(e.g. timing of migration, reproduction, hibernation) remains poorly
understood. Further integration of insights from physiologists,
evolutionary biologists, and population ecologists working on wild
populations will improve our collective understanding of the effects of
seasonal climatic shifts on mammalian hibernator life history traits, key
drivers of their population-level persistence.