Predator-prey relationships involving rabbits and hares are widely studied at a long-term population level, while the short-term ethological interactions between one predator and one prey are less well documented. We use a physiologically-based model of hare behavior, developed in the framework of artificial intelligence studies, to analyse its sophisticated anti-predatory behavior. The hares use to stand to the fox in order to inform it that its potential prey is alerted. The behavior of the hare is characterized by specific standing and flushing distances. We show that both hare survival probability and body condition depend on habitat cover, as well as on the ability of the predator to approach-undetected-a prey. We study two anti-predatory strategies, one based on the maximization of the survival probability and the other on the maximization of the body conditions of the hare. Despite the fact that the two strategies are not independent, they are characterized by quite different behavioral patterns. Field estimates of flushing and standing distances are consistent with survival maximization. There exists an optimal anti-predatory strategy, characterized by a flushing distance of 20 m and a standing distance of 30 m, which is optimal in a large set of environmental conditions with a sharp fitness advantage with respect to suboptimal strategies. These results improve our understanding of the anti-predatory behavior of the hare and lend credibility to the optimality approach in the behavioral analysis, showing that even for complex organisms, characterized by a large network of internal constraints and feedback, it is possible to identify simple optimal strategies with a large potential for selection.

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A two-year field study on selected traits of the biology of the scarabaeine dung roller Sisyphus schaefferi (Linnaeus) was conducted in a natural park in the western Po Valley in northwestern Italy. Despite laboratory studies carried out over the past few decades, several aspects of the epigean behavior of the species in the wild remain uncertain. Our study revealed that 1) the species is active from early spring to late summer, with reproductive pairs being observed from mid-spring to midsummer; 2) sexual dimorphism in body weight and length is absent; 3) mating individuals are significantly heavier and longer than non-mating individuals; 4) metatibial length increases isometrically with body length and weight; 5) size and weight of the brood balls are isometric with respect to the length and weight of the male of the reproductive pair; 6) brood balls are significantly larger and heavier than food balls, and, whereas brood ball size and weight decrease as air temperature increases, food ball size and weight increase as air humidity rises, but only in non-reproductive periods; 7) pushing and pulling roles are not sex-dependent and can be reversed during the rolling process; 8) combat for balls can involve up to six individuals simultaneously.

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