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Animals can perceive tourists as predators and will incur fitness costs should their predator-avoidance behaviours result in forgone resource acquisition. Not all wildlife, however, treat tourists as predators; animals can respond positively to tourists, especially when food is used as an attractant. We investigate the costs posed by novel grouping over a tourism-provisioned food resource in a normally solitary forager, the southern stingray Dasyatis americana, in Grand Cayman. Specifically, we test the hypotheses that group-living stingrays in a new environment-which includes both the presence of tourists and quickly renewing food patches-will be exposed to increased injuries, ecto-dermal parasites and aggressive interference competition that result from the unusual grouping behaviour. We found that, in comparison to stingrays from non-tourist sites, touristfed stingrays are more likely to have lower body condition, be injured by boats and predators, be susceptible to ecto-dermal parasites, and be engaged in intense interference competition (in the form of conspecific bite marks). Stingrays from tourist sites also have significantly higher mean numbers of injuries, parasites, and median bite marks. By exploring alternative hypotheses to explain the pattern of our findings (e.g. natural causes/behaviour), we unequivocally show that the impacts incurred by the stingrays stem from the effects of tourism. These findings suggest that novel grouping poses costs to the stingrays; the tourist site represents a riskier habitat with regards to injury and predation; and there may be long-term fitness consequences. From a management perspective, measures should be taken to alleviate the crowded conditions at tourist sites, in terms of both boat and stingray density.

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Animal foraging may be influenced by multiple demands simultaneously (eg., nutrient gain and predator avoidance). Conventional approaches to understand the trade-ofii between these demands require cramming them in ffmilar currencies, which is impractical in many field situations. We introduce a new method, called multiobjective programming, as a framework to explore how animals balance conflicting demands. Multiobjective programming allows one to explore die influence of foraging demands directly, without explicit assumptions about how they enter into fitness and without conversion to some common currency. Using multiobjective programming, we show that, as foraging demands change, animait may adaptivety adjust their behavior, even if the constraints on feasible behavior are unaffected (contrary to die predictions of the conventional models). Hence, we may see a variable response in foraging that is consistent with adaptive behavior. We used an empirical test with herbivore grasshoppers and predator spiders to evaluate die utility of multiobjective programming Our experiments show that grasshoppers are able to optimally balance die foraging objectives of energy intake and vigilance under changing levels of predation risk. The multiobjective model is used both to evaluate die biological «ignifiranrf of the broad variation that was observed in die grasshoppers' foraging behavior and to quantify explicitly die trade-off between energy intake and predator avoidance.

Feeding marine wildlife as a tourism experience has become a popular means by which to attract both people and wildlife, although management efforts are still in their infancy. "Stingray City Sandbar" in the Cayman Islands, where visitors can hand feed free-ranging Southern Stingrays (Dasyatis americana), is a world-famous attraction currently undergoing visitor and wildlife management. One plan is to decrease the amount of nonnatural food provided by tourists with the intention of decreasing stingray habituation to the artificial food source and promoting stingray health. However, the effectiveness of this action is uncertain given that neither the extent of squid composition in the stingray diet nor the degree of nutrient similarity between the fed and natural diets is unknown. We used fatty acid (FA) profile analysis to address these questions by assessing the serum nonesterified FA composition of fed and unfed stingrays around the island and compared them with FA profiles of (1) the provisioned food source (squid) and (2) other warm- and cold-water elasmobranchs (sharks and rays). Our results indicated that fed stingrays were distinct. The FA profiles of the fed stingray population were expressly different from those of the unfed populations and showed a remarkable similarity to the FA composition of squid, suggesting that squid is the main food source. The tropical fed stingrays also exhibited essential FA ratios, specific to both species and habitat, comparable with those of elasmobranchs and squid from cold-water environs, implying that the provisioned food does not provide a similar nutritional lipid composition to that eaten in the wild. Our results suggest that FA profiles are a valuable indicator for the management and monitoring of fed Southern Stingrays because they can be used to assess differences in diet composition and provide an index of nutritional similarity. Our findings are currently being used by Caymanian stakeholders in designing practical management actions for their wildlife attraction.