Abstract: Two sets of experiments are reported that show that the small green bee-eater ( Merops orientalis, a small tropical bird) can appreciate what a predator can or cannot see. Bee-eaters avoid entering the nest in the presence of a potential nest predator. In the first set of experiments bee-eaters entered the nest more frequently when the predator was unable to see the nest from its position, as compared to an approximately equidistant position from which the nest could be seen. In the second set of experiments bee-eaters entered the nest more frequently when the predator was looking away from the nest. The angle of gaze from the nest was associated significantly positively with the probability of entering the nest whereas the angle from the bird was not. Birds showed considerable flexibility as well as individual variation in the possible methods of judging the predator's position and direction of gaze.

Abstract: Past studies of galliform anti-predator behavior show that they discriminate between aerial and ground predators, producing distinctive, functionally referential vocalizations to each class. Within the category of aerial predators, however, studies using overhead models, video images and observations of natural encounters with birds of prey report little evidence that galliforms discriminate between different raptor species. This pattern suggests that the aerial alarm response may be triggered by general features of objects moving in the air. To test whether these birds are also sensitive to more detailed differences between raptor species, adult chickens with young were presented with variously sized trained raptors (small, intermediate, large) under controlled conditions. In response to the small hawk, there was a decline in anti-predator aggression and in aerial alarm calling as the young grew older and less vulnerable to attack by a hawk of this size. During the same developmental period, responses to the largest hawk, which posed the smallest threat to the young at all stages, did not change; there were intermediate changes at this time in response to the middle-sized hawk. Thus the anti-predator behavior of the adult birds varied in an adaptive fashion, changing as a function of both chick age and risk. We discuss these results in light of current issues concerning the cognitive mechanisms underlying alarm calling behavior in animals.

Abstract: Prey species show specific adaptations that allow recognition, avoidance and defense against predators. For many mammalian species this includes sensitivity towards predator-derived odors. The typical sources of such odors include predator skin and fur, urine, feces and anal gland secretions. Avoidance of predator odors has been observed in many mammalian prey species including rats, mice, voles, deer, rabbits, gophers, hedgehogs, possums and sheep. Field and laboratory studies show that predator odors have distinctive behavioral effects which include (1) inhibition of activity, (2) suppression of non-defensive behaviors such as foraging, feeding and grooming, and (3) shifts to habitats or secure locations where such odors are not present. The repellent effect of predator odors in the field may sometimes be of practical use in the protection of crops and natural resources, although not all attempts at this have been successful. The failure of some studies to obtain repellent effects with predator odors may relate to (1) mismatches between the predator odors and prey species employed, (2) strain and individual differences in sensitivity to predator odors, and (3) the use of predator odors that have low efficacy. In this regard, a small number of recent studies have suggested that skin and fur-derived predator odors may have a more profound lasting effect on prey species than those derived from urine or feces. Predator odors can have powerful effects on the endocrine system including a suppression of testosterone and increased levels of stress hormones such as corticosterone and ACTH. Inhibitory effects of predator odors on reproductive behavior have been demonstrated, and these are particularly prevalent in female rodent species. Pregnant female rodents exposed to predator odors may give birth to smaller litters while exposure to predator odors during early life can hinder normal development. Recent research is starting to uncover the neural circuitry activated by predator odors, leading to hypotheses about how such activation leads to observable effects on reproduction, foraging and feeding. © 2005 Elsevier Ltd. All rights reserved.

Abstract: Animals' improvement in capturing cryptic prey with experience has long been attributed to a perceptual mechanism, the specific search image. Detection could also be improved by adjusting rate of search. In a series of studies using both naturalistic and operant search tasks, pigeons searched for wheat, dyed to produce 1 conspicuous and 2 equally cryptic prey types. Contrary to the predictions of the search-rate hypothesis, pigeons given a choice between the 2 cryptic types took the type experienced most recently. However, experience with 1 cryptic type improved accuracy on the other cryptic type, a result inconsistent with a search image specific to 1 prey type. Search image may better be thought of as priming of attention to those features of the prey type that best distinguish the prey from the background.

Abstract: Over 45 million years of evolution the horse developed to a highly specialized animal in anatomy, physiology and behavior. No other animal had influenced the economic and cultural history of men to such extent. Hunting prey since the ice age, domesticated 4000 B.C. and used for thousands of years as unique animal all over the world has attained a new role today as partner in sport, as companion animal and even as cotherapeutic. The well known behavioral demands in use and keeping are still often not fulfilled.