Supplemental feeding alters migration of a temperate ungulate

Abstract

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that management practices applied in one season may have unintended behavioral consequences in subsequent seasons.

Sound settlement: noise surpasses land cover in explaining breeding habitat selection of secondary cavity‐nesting birds

“…We then calculated 85% confidence intervals (and also report 95% CIs in Appendix S1: Tables S1 and S2) for each predictor included in the set of models <2 ΔAIC c and identify informative predictors as those not overlapping zero (Arnold 2010, Jones et al 2014, Kirol et al 2015, Ware et al 2015. Those near-zero variance random effects (i.e., variance ≤ 0.0001) whose exclusion improved the fit of the model were also removed.…”

Loss of migratory behaviour increases infection risk for a butterfly host

“…These animals comprise a significant portion of global biodiversity, and their migratory behaviours have large effects on ecosystem processes [1,2]. In recent decades, numerous migratory species have declined or altered their migratory behaviours in response to anthropogenic environmental change [3][4][5]; some populations now migrate shorter distances or have transitioned into year-round resident populations [6][7][8]. For instance, numerous bird species have shown a reduced migratory tendency linked to climate warming [6], or established new non-migratory populations owing to habitat loss or supplemental feeding by humans (e.g.…”

Linking spring phenology with mechanistic models of host movement to predict disease transmission risk

“…In the Mountain West, climate change is contributing to decreased snowpack, earlier snowmelt, and an increase in drought frequency and the rate of spring green‐up (Bates, Kundzewicz, Wu, & Palutikof, ; Joyce, Haynes, White, & Barbour, ). Plant phenology strongly determines wild ungulate habitat use (Aikens et al., ) and selection (Merkle et al., ), including elk in our study area (Jones et al., ). To evaluate the influence of snow depth and vegetation phenology on brucellosis transmission risk, we predicted the spatio‐temporal distribution of abortion events across five winter weather scenarios: observed low, average and heavy snow years; and two extreme early snowmelt or winter drought scenarios.…”

“…Elevations above 2,900 m are predominated by herbaceous meadows, and spruce ( Picea engelmannii ), subalpine fir ( Abies lasiocarpa ) and whitebark pine ( Pinus albicaulis ) forests. The regional climate is characterized by long cold winters and relatively short warm summers (see Jones et al., for details).…”

“…We developed and fit a SSF for elk movement on and around each feedground (i.e., a feedground subpopulation) from the day supplemental feeding ended to 15 July (when brucellosis‐induced abortion risk is predicted to be nearly zero; Cross et al., ). We fit SSFs separately for each feedground because we expected each subpopulation to behave differently based on previous analyses (Jones et al., ). For each four‐hour step, we drew 10 potential target points originating from the known source point by simultaneously sampling step and turning angle distributions of all animals in the subpopulation.…”