DOI: 10.5061/dryad.jm63xsj9q
title: Experimental repatriation of snowshoe hares along a southern range boundary reveals historical community interactions

description: Climate change is altering interspecific interactions globally, yet
 community-level responses are difficult to predict due to both the direct
 and indirect effects of changing abiotic and biotic conditions. Snowshoe
 hares (Lepus americanus) are particularly vulnerable to decreasing snow
 cover and resultant camouflage mismatch. This species shares a suite of
 predators with alternative prey species including porcupines (Erethizon
 dorsatum) and ruffed grouse (Bonasa umbellus), and all three species
 historically exhibited synchronized population dynamics. Recently, the
 community has become partially disassembled, notably with the loss of
 snowshoe hares and associated enemy-mediated indirect interactions
 resulting from declining snow duration. Specifically, we hypothesized that
 the extirpation of hares in the early 1990s indirectly increased predation
 pressure on ruffed grouse and porcupines. To test our hypothesis, we
 experimentally translocated 96 snowshoe hares to a site within a regional
 ecotone between northern and southern forests where snowshoe hares were
 recently extirpated and monitored community members before, during and
 after translocation. Ruffed grouse were only loosely associated with the
 biotic interactions that linked porcupines and snowshoe hares, likely due
 to predation occurring from avian predators and strong negative direct
 effects of declining winter snow depths. In contrast, predation of neonate
 porcupines was virtually non-existent following repatriation, compared to
 periods without hares. This abrupt attenuation of predation did not
 increase overall survival due to increased non-predation mortality from
 cold, early spring weather. Porcupines directly benefitted from warming
 winters: decreased snow cover increased adult survival and warmer
 temperatures around parturition increased maternal condition and reduced
 non-predation causes of mortality for neonates. Our experimental
 manipulation suggests that enemy-mediated indirect interactions were
 likely important features of this community; however, climate change has
 disrupted these interactions, resulting in extirpation of a central prey
 species (snowshoe hare) and increased predation of an alternative prey
 species (porcupine). We show complex effects from climate change with some
 species directly and negatively affected, while others benefitted from
 direct effects of warming winters, but suffered negative effects from
 indirect interactions. Absent snowshoe hares and associated biotic
 interactions, continued persistence of this community module is unlikely,
 potentially resulting in altered no-analogue communities along trailing
 edge distributions.
description: Data were collected on Porcupine (<em>Erethizon
 dorsatum</em>) and ruffed grouse (<em>Bonasa
 umbellus</em>) at Sandhill Wildlife Area in central Wisconsin
 between 1968 and 2018. Census data on porcupine was collected annually
 between 1968 and 2018 (Wilsonetal_Grouse_Porcupine_Counts). Survival data
 for adult, subadult and juvenile porcupines was collected annually between
 1997 and 2018 (Wilsonetal_CJS). Survival data for grouse was collected
 between 2016 and 2018 (Wilsonetal_Grouse_KnownFate). Cause-specific
 mortality data on neonate porcupines was collected between 2015 and 2018
 (Wilsonetal_NPCIF & Wilsonetal_CPH). Cause-specific risk factor
 data was Metrics of maternal condition were generated using capture data
 on pregnant females (Wilsonetal_Res1), and posthoc analysis of predictors
 of maternal condition were performed using climatic and seasonal data
 (Wilsonetal_MaternalCondition).
description: Details on files and variables used in analysis are listed in the
 README file