Home sweet home: fitness consequences of site familiarity in female black-tailed deer

Abstract

Individual animals strive to maximize fitness by gaining access to food while minimizing predation risk, and spatial knowledge of both forage resources and predation risks has long been presumed to be advantageous. Actual fitness benefits of site familiarity, however, have rarely been demonstrated. We placed GPS collars on 57 female black-tailed deer in coastal California over 4 years to track seasonal movements, determine home ranges, and monitor survival and cause of mortality. We used seasonal home ranges and core areas as measures of site familiarity and modeled how mortality risk varied with use of familiar areas, forage availability, age class, and elevational overlap with simultaneously collared pumas using Cox proportional hazards models. The use of familiar areas was the best predictor of mortality risk, and deer that had a 40 % probability of leaving their home range in a given week were four times more likely to die.Puma predation was the largest cause of mortality, and deer whose average weekly elevation was farther from the average elevation of pumas were less likely to die. While forage availability was not related to mortality risk, deer with lower forage availability were more likely to leave their home range during both summer and winter. Our results provide a rare example of fitness benefits associated with site familiarity and the use of familiar areas as a refuge from predation. The benefits of site familiarity are likely widespread in ungulates, especially when there are stable home ranges, complex habitats, and few cues of predation risk.

Seeking sanctuary: the neonatal calving period among central mountain woodland caribou (Rangifer tarandus caribou)

“…Furthermore, reducing fidelity as a predatoravoidance strategy is consistent with our observation of lower calving-range fidelity at higher seismic-line densities because these features are associated with increased risk of wolf encounters during the spring calving period (Whittington et al 2011). Ultimately, low range fidelity may have negative fitness consequences among caribou because spatial memory is integral to space-use decisions (Avgar et al 2015) and when ungulates are not familiar with their surroundings they can suffer from higher mortality (Forrester et al 2015) and reduced foraging efficiency (Merkle et al 2014). …”

Effect of activity states on habitat selection by black‐tailed deer

“…In winter, black‐tailed deer descended to lower elevations and selected northeastern aspects. Because of the low interspersion of these variables in space, and very small home ranges of our study individuals (Forrester et al , Bose et al ), the pattern of selection remained consistent across activity states. Selection patterns for slope in black‐tailed deer, however, showed opposing patterns across activity states that affected the outcome of the pooled models.…”

Mechanisms of coexistence in diverse herbivore–carnivore assemblages: demographic, temporal and spatial heterogeneities affecting prey vulnerability

“…Herbivores should minimize this product, by adjusting their habitat choice and activity patterns in the context of temporal variation in seasonal conditions and time of day. This entails tradeoffs between remaining in the most secure and familiar locations and tolerating food limitations and deteriorating physiological condition with its consequences for survival, against exposure to higher risk of predation compensated by greater food availability, in a changing seasonal context (Forrester et al ).…”