Examining the impact of climate change on snowshoe hare demography and community interactions in the northern boreal forest

• Author / Creator

  Peers, Michael JL

• Ecologists are under increasing pressure to predict the influence of climate change on species demography along with the broader impacts on community and ecosystem structure. Predicting community responses to climate change, however, is a formidable challenge, that can be ameliorated by developing a better 1) mechanistic understanding of how climate influences community interactions, and 2) detailed understanding of the current factors limiting species abundance. Snowshoe hare (Lepus americanus) are an important prey species of the boreal forest that undergo 10 year population cycles. Hares are well-suited for snowy boreal winters, having large feet allowing for low foot loading and therefore improved flotation in deep, soft snow, giving them an advantage over their predators. In this thesis, I examine the potential impact of changes in winter climate on hare demography and community interactions, as well as the primary factors driving their fluctuations in abundance. I found that shallow snow reduced hare survival, to rates resembling those during cyclic population declines. This response was primarily driven through an increase in predation risk from coyotes (Canis latrans), as risk from their main predator Canada lynx (Lynx canadensis) was largely unaffected by snow depth. I further found that changes in hare density can influence community structure beyond predator-prey dynamics. The efficiency of the scavenging community was affected by hare density, with carcass persistence decreasing when snowshoe hare densities declined, mainly due to increased scavenging rates by their predator, the Canada lynx. In addition, scavenging rates in the boreal forest increased in warmer temperatures, suggesting climate change may increase scavenging efficiency in this system. Finally, I found that hare cycles may not be regulated by predator induced stress reducing reproductive output. Instead, changes in population growth following decline correspond with improved over-winter survival of juveniles, particularly for juveniles born earlier in the summer. However, the importance of changes in reproductive rates on hare demography should be investigated further, and I discuss potential experiments that may help decipher the role of predator fear regulating snowshoe hare populations. Overall, this thesis demonstrates that climate change can impact snowshoe hare demography indirectly through shifts in predation risk, and could have broad effects on community interactions in the northern boreal forest.

• Subjects / Keywords

  • Snowshoe hare
  • Population cycles
  • Predator-prey interactions
  • Community ecology
  • Climate change
  • Population dynamics

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-fs3p-rf98

• License

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