Summary1. In the face of natural complexities and multicollinearity, model selection and predictions using multiple regression may be ambiguous and risky. Confounding effects of predictors often cloud researchers' assessment and interpretation of the single best 'magic model'. The shortcomings of stepwise regression have been extensively described in statistical literature, yet it is still widely used in ecological literature. Similarly, hierarchical regression which is thought to be an improvement of the stepwise procedure, fails to address multicollinearity. 2. We propose that regression commonality analysis (CA), a technique more commonly used in psychology and education research will be helpful in interpreting the typical multiple regression analyses conducted on ecological data. 3. CA decomposes the variance of R 2 into unique and common (or shared) variance (or effects) of predictors, and hence, it can significantly improve exploratory capabilities in studies where multiple regressions are widely used, particularly when predictors are correlated. CA can explicitly identify the magnitude and location of multicollinearity and suppression in a regression model. In this paper, using a simulated (from a correlation matrix) and an empirical dataset (human habitat selection, migration of Canadians across cities), we demonstrate how CA can be used with correlated predictors in multiple regression to improve our understanding and interpretation of data. We strongly encourage the use of CA in ecological research as a follow-on analysis from multiple regressions.

Foraging animals have several tools for managing the risk of predation, and the foraging games between them and their predators. Among these, time allocation is foremost, followed by vigilance and apprehension. Together, their use influences a forager's time allocation and giving-up density (GUD) in depletable resource patches. We examined Allenby's gerbils (Gerbilus andersoni allenbyi) exploiting seed resource patches in a large vivarium under varying moon phases in the presence of a red fox (Vulpes vulpes). We measured time allocated to foraging patches electronically and GUDs from seeds left behind in resource patches. From these, we estimated handling times, attack rates and quitting harvest rates (QHRs). Gerbils displayed greater vigilance (lower attack rates) at brighter moon phases (full , wane , wax , new). Similarly, they displayed higher GUDs at brighter moon phases (wax . full . new . wane). Finally, gerbils displayed higher QHRs at new and waxing moon phases. Differences across moon phases not only reflect changing time allocation and vigilance, but changes in the state of the foragers and their marginal value of energy. Early in the lunar cycle, gerbils rely on vigilance and sacrifice state to avoid risk; later they defend state at the cost of increased time allocation; finally their state can recover as safe opportunities expand. In the predator-prey foraging game, foxes may contribute to these patterns of behaviours by modulating their own activity in response to the opportunities presented in each moon phase.

How foragers balance risks during foraging is a central focus of optimal foraging studies. While diverse theoretical and empirical work has revealed how foragers should and do manage food and safety from predators, little attention has been given to the risks posed by dangerous prey. This is a potentially important oversight because risk of injury can give rise to foraging costs similar to those arising from the risk of predation, and with similar consequences. Here, we synthesize the literature on how foragers manage risks associated with dangerous prey and adapt previous theory to make the first steps towards a framework for future studies. Though rarely documented, it appears that in some systems predators are frequently injured while hunting and risk of injury can be an important foraging cost. Fitness costs of foraging injuries, which can be fatal, likely vary widely but have rarely been studied and should be the subject of future research. Like other types of risk-taking behaviour, it appears that there is individual variation in the willingness to take risks, which can be driven by social factors, experience and foraging abilities, or differences in body condition. Because of ongoing modifications to natural communities, including changes in prey availability and relative abundance as well as the introduction of potentially dangerous prey to numerous ecosystems, understanding the prevalence and consequences of hunting dangerous prey should be a priority for behavioural ecologists.

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Many small carnivores include rodents in their diet. However, due to varying evolutionary strategies, carnivores differ in their metabolism and energy requirements. Hence, comparisons of diet between carnivores would be more meaningful if the body size and energetics of the predators are considered. The diet of three small carnivores (jungle cat Felis chaus; caracal Caracal caracal; golden jackal Canis aureus) from a semi‐arid part of western India was studied through scat analysis, and the importance of rodents in their diet was estimated as a percentage of their daily energy requirement. Although percentage frequency in scats and biomass consumption showed rodents to be equally important to all three carnivores, energy calculations showed that rodents were more important as prey for the felids than the jackal. Up to 70% of the daily metabolizable energy in felids was obtained from rodents, as compared to 45% in the jackal. Rodents are generally viewed as pests, and their importance to the small carnivore community is overlooked. Change in land use over the decades in the arid/semi‐arid tract of western India has led to several adverse as well as favourable modifications in rodent assemblages, which could influence the persistence of species like the caracal and jungle cat in this region, that largely depend on rodents for their survival.

In the foraging game between gerbils and their predators, gerbils manage risk of predation using the tools of time allocation (where, when and for how long to forage) and vigilance. Th e optimal level of a forager ' s vigilance should be aff ected by its encounter rate with predators and the eff ectiveness of its vigilance in reducing mortality risk. Th e physical structure of the environment can alter the eff ectiveness of its vigilance and therefore alter its foraging behaviour. We tested this for gerbils at risk of predation from barn owls or foxes in a large vivarium. In particular, we reduced the eff ectiveness of vigilance by placing obstructions around feeding trays that blocked sight lines along either the vertical (vigilance directed against owls) or horizontal axis (vigilance directed against foxes), thereby changing the physical structure of the environment. In addition, we manipulated the presence of foxes and owls. In general, gerbils harvested fewer seeds, allocated less time to foraging in dangerous patches, and used more vigilance while foraging where and when risks were higher (i.e. in the presence of predators and in bright moonlight). Vertical and horizontal sightline treatments interacted synergistically to further raise perceived risk.Th ese results imply that blocking sight lines reduces the eff ectiveness of vigilance, causing gerbils to use it less. Moreover, in the presence of a predator, the gerbils ' response to the blocked sightlines was more severe -harvesting less food and spending less time and vigilance -in the patches with the increased risk. Th is was especially so in the presence of the predator that was expected to most benefi t from blocking that particular type of sight line: cover that blocked vertical sight lines was riskiest in the presence of owls, and cover that blocked horizontal sight lines was riskiest in the presence of foxes. Th ese results strongly indicate the importance of sightlines and landscape features such as bushes in the risk management and forging decisions of gerbils, demonstrating that bush cover provides mixed blessing to gerbils by providing cover, but making vigilance ineff ective.Th e clever forager reacts to the risk of predation by using behavioral tools such as time allocation and vigilance to reduce and manage the risk to which it is exposed (Lima 1987a).Apprehension and vigilance are behavioral tools used by animals to detect risks when foraging, including those from predators (Kotler et al. 2004a) and potential competitors for food and territory (Lima 1987b). Apprehension is defi ned as any reduction in attention to other activities (e.g. foraging) as a result of increasing the allocation of attention given to detecting and/or responding to potential predator activity . Kotler et al. (2004b) showed that gerbils foraged less effi ciently under complex conditions when risk of predation was high, as their attention was not wholly on the task at hand. Vigilance is defi ned as a special case where apprehension is total (i.e. all attention is direct...

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Predator-prey studies often assume a three trophic level system where predators forage free from any risk of predation. Since meso-predators themselves are also prospective prey, they too need to trade-off between food and safety. We applied foraging theory to study patch use and habitat selection by a meso-predator, the red fox. We present evidence that foxes use a quitting harvest rate rule when deciding whether or not to abandon a foraging patch, and experience diminishing returns when foraging from a depletable food patch. Furthermore, our data suggest that patch use decisions of red foxes are influenced not just by the availability of food, but also by their perceived risk of predation. Fox behavior was affected by moonlight, with foxes depleting food resources more thoroughly (lower giving-up density) on darker nights compared to moonlit nights. Foxes reduced risk from hyenas by being more active where and when hyena activity was low. While hyenas were least active during moon, and most active during full moon nights, the reverse was true for foxes. Foxes showed twice as much activity during new moon compared to full moon nights, suggesting different costs of predation. Interestingly, resources in patches with cues of another predator (scat of wolf) were depleted to significantly lower levels compared to patches without. Our results emphasize the need for considering risk of predation for intermediate predators, and also shows how patch use theory and experimental food patches can be used for a predator. Taken together, these results may help us better understand trophic interactions.