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Increasing impacts of wildfire on arid regions of the world fuelled by climate change highlight the need to better understand how natural communities respond to fire. We took advantage of a large (1660‐km2) wildfire that erupted in northern California during an in‐progress study of black‐tailed deer (Odocoileus hemionus columbianus) to investigate deer use of and diets within burned and unburned habitats before and after the fire. We compared deer diet breadth to predictions of optimal foraging theory, the niche variation hypothesis, and opportunistic (i.e., generalist) foraging expectations under the assumption that overall availability and diversity of forage in burned areas declined immediately after the fire and increased as the plant community recovered in the next 3 years after the fire. We used faecal pellet counts to document space use and metabarcoding to study diet during pre‐fire, post‐fire, and recovery periods. Pellet counts supported predictions that deer increased use of unburned sites and reduced use of burn sites after the fire and began to return to burned sites in subsequent sampling years. Diet diversity did not differ significantly between control and burn sites before the fire, but was lower in burn than control sites post‐fire (p <.001), when and where diet was dominated by oak (Quercus spp). In contrast, during subsequent years, diet diversity was higher (including more herbaceous plants) in burn than control sites (p <.05). In contrast to predictions of optimal foraging and niche variation hypotheses, individual deer foraged as generalists for which changes in dietary niche breadth paralleled fire‐induced changes in diversity of the plant community. [ABSTRACT FROM AUTHOR]

Pumas (Puma concolor) are solitary large carnivores that exhibit high energetic investments while hunting prey that often take multiple days to consume. Therefore, pumas should behave in a way to maximize their energetic gains, including using caching, which is a behavior used by many mammal species to preserve and store food or to conceal it from conspecifics and scavengers to limit their losses. Yet pumas do not always cache their kills. In order to understand caching behavior, we used variables associated with the kills such as prey mass, search time, climate, and habitat to test 20 ecological models (representing four a priori hypotheses: food perishability, resource pulse, consumption time, and kleptoparasitism deterrence) in an information-theoretic approach of model selection to explore factors related to the caching behavior. Models were run with information from tracked radio-collared pumas in California over a 2.5-year period and identified a total of 352 kills. Overall, we documented pumas caching 61.5% of their kills, including 71.6% of Black-tailed Deer (Odocoileus hemionus columbianus), their primary prey in the study area. The model with a quadratic effect of adjusted mass of prey on puma caching probability had all of the empirical support (w = 1.00). Specifically, pumas were most likely to cache intermediate-sized prey, such as yearling and adult female deer, and also fed from cached kills for longer periods of time. Larger prey may be too large to easily cache, making it less energetically efficient—while small prey can often be consumed quickly enough to not require caching. This suggests that intermediate-sized prey may be the optimal size for caching, allowing a puma to feed for multiple days while not greatly increasing energetic output. The hypotheses we tested were not mutually exclusive and pumas caching their prey may occur for several reasons; nevertheless, our study demonstrated that pumas use caching to extend their foraging time and maximize energetic gains when preying on intermediate-sized prey. [ABSTRACT FROM AUTHOR]

Exploitative competition between two sympatric guild members can influence the composition and dynamics of an ecological community. We assessed potential exploitative competition between desert kit foxes (Vulpes macrotis arsipus) and coyotes (Canis latrans) by comparing food habits of the two species from 2009 to 2014 on a study site in the Mojave Desert in California. Desert kit foxes specialised on heteromyid rodents and invertebrates, while the most frequently occurring items consumed by coyotes were lagomorphs and rodents. Both species consumed a variety of food items throughout the study, but relative use of these items varied with year and season. Also, precipitation affected prey abundance, and this influenced prey consumption by the two species. The diets of desert kit foxes and coyotes overlapped extensively, which indicated possible exploitative competition. Desert kit foxes consistently had lower dietary diversity than coyotes, indicating that desert kit foxes are more specialist consumers while coyotes are more generalists. Dietary specialisation by kit foxes on smaller items may help reduce competition with coyotes and facilitate coexistence. Coyotes consumed anthropogenic material at much higher frequencies than desert kit foxes, and this subsidisation could increase competitive pressures on kit foxes if it results in greater coyote abundance. Desert kit foxes in California are not a protected species although formal protection has been proposed due to increasing human encroachment. Conservation strategies should include measures to maintain an abundance and diversity of natural food items and limit anthropogenic subsidisation of coyotes. Desert kit foxes (Vulpes macrotis arsipus) and coyotes (Canis latrans) in the Mojave Desert in California use similar food items and may engage in exploitative competition. However, kit foxes specialised on rodents and invertebrates while coyotes were more generalist consumers. Dietary specialisation by kit foxes may help reduce competition with coyotes. [ABSTRACT FROM AUTHOR]

Abstract: California archaeologists have proposed two alternative methods for harvesting mussels—“stripping” and “plucking”. These two methods are modeled and compared with experimental data from central California (Jones, T.L., Richman, J.R., 1995. On Mussels: Mytilus californianus as a Prehistoric Resource, North American Archaeologist 16, 33–58) and archaeological data from the Punta Gorda Rockshelter, a well-stratified coastal shell midden in northern California. Foragers at the Punta Gorda Rockshelter appear to have practiced a “stripping” technique at approximately 24month intervals. It is argued that, while this strategy reduced immediate foraging returns, it increased the long-term net productivity of the mussel beds. These findings are discussed in light of the broader literature regarding resource depression and resource cultivation in California prehistory. The conventional interpretation of reductions in the body size in archaeological assemblages is questioned both in terms of rates of return on these individuals and the impact of human predation on local prey populations. [Copyright &y& Elsevier]

Natural selection is expected to favor the evolution of threat-sensitive behaviors that permit individuals to adaptively detect and respond to danger. However, because time allocated to vigilance reduces the amount of time that is available for energy acquisition, foraging in the face of predation can impose an evolutionary trade-off. Optimal foraging theory therefore predicts that risk-taking decisions should vary in response to perceived levels of threat. Our goal here is to disentangle the relative contributions of conspecific presence, ecological factors, and individual traits on two measures of vigilance in free-living California ground squirrels (Otospermophilus beecheyi). This facultatively social and ecologically flexible rodent represents a major source of prey in California grasslands. Over a 5-year period, we collected 386 focal animal surveys on 156 free-living individuals residing at two colony sites. Individuals were most vigilant in conditions for which predation risk was highest, such as when foraging alone and on flat areas with low vegetative cover. In general, juvenile foragers were more gregarious but less vigilant than adult foragers. Although all animals—regardless of age or sex—generally decreased their intensity of vigilance as group size increased, only adults decreased their time allocated to vigilance in response to conspecific presence. Thus, grouping consistently buffered the costs of foraging for risk-averse adults, but the benefits of conspecific presence were less salient for juveniles. Taken together, our findings highlight the importance of context in shaping foraging decisions and offer insights into the suite of factors mediating decision-making in socially and ecologically variable environments. Significance statement: Animals face trade-offs when foraging in the face of predation, but the capacity for individuals to respond appropriately to subtle changes in context-dependent threats remains poorly understood. We studied antipredator vigilance by the California ground squirrel, a flexible species that may forage alone or in small groups of various sizes and in habitats that vary in their protective value from predators and the ease at which prey may detect predators. Although adults are more sensitive to changes in group size, all animals detected context-dependent danger to some extent. Our findings offer insights into the multiple factors that prey respond to when making foraging decisions, suggesting that animals possess the ability to integrate disparate sources of information about danger to optimize energy gain. [ABSTRACT FROM AUTHOR]