Data from: Population dynamics of a northern-adapted mammal: disentangling the influence of predation and climate change

Community structure and interspecific interactions are particularly
vulnerable to rapidly changing climatic regimes. Recent changes in both
climate and vertebrate community assemblages have created a unique
opportunity to examine the impacts of two dynamic forces on population
regulation. We examined the effects of warming winter conditions and the
reestablishment of a previously extirpated predator, the fisher (Martes
pennanti), on regulatory mechanisms in a northern-adapted mammal, the
porcupine (Erethizon dorsatum), along their southern range boundary. Using
a long-term (17-year) capture–recapture data set, we (1) quantified the
impacts of climate change and increased fisher predation on the survival
of adult porcupines at their regional southern terminus, (2) assessed
recruitment (via both adult fecundity and juvenile survival) of
porcupines, and (3) modeled the relative importance of predation and
winter conditions on the demography and population growth rate (λ). Severe
winters and abundant predators interacted synergistically to reduce adult
survivorship by as much as 44%, while expanding predator populations led
to near reproductive failure among porcupines. Increasing predatory
pressure, disruptions in this community module, and more frequent extreme
winter weather events led to predicted extirpation within 50 years,
whereas in the absence of predators, the population was viable. Our
results provide a mechanistic understanding behind distributional shifts
resulting from climate change and may be broadly relevant for predicting
future distributional shifts in other northern-adapted mammalian species.