Unusual behaviour by Rattus norvegicus.
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An adult male chimpanzee living in Gombe National Park, Tanzania, was observed for 50 consecutive days during the 1974 dry season, for a total of 563 h. This individual, Figan, was the alpha male of a community of 42 chimpanzees. The composition and size of temporary associations within the community was influenced largely by the presence of one estrus female and by characteristics of the food resources. Figan's daily time budget varied little for travel and grooming, but there were major changes in time spent feeding tha inactive over the 50 days. Predatory behavior occurred periodically and meat was eaten on five occasions. Agonistic and sexual behaviors are discussed relative to Figan's high social status. A cooperative relationship was maintained between Figan and his older brother.
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Carrying heavy objects is a common element in the foraging and building behavior of ants. The initial stages of this behavior, i.e., lifting and moving in T. caespitum displayed as stereotyped patterns of movement. These patterns do not improve as the ants become older and more experienced, which suggest their congenital nature. Growing experience of ants is manifested in the later stages of the transportation of heavy objects, and especially in entering the correct opening of the nest with the carried prey. When a foraging ant leaves its nest to return to the prey it initially moves in the general direction of its objective. It is not until a certain distance from the nest is reached, that the ant is able to use olfactory stimuli to locate and follow its previous path. These observations indicate that the representatives of this species do not learn an exact way to and from the nest but instead have a memory for direction. The congenital character of these basic elements of foraging and building behavior allows the existence of a social organization without a division of work and foraging areas.
Equally sated three-spined sticklebacks (Gasterosteus aculeatus) that had a free view of stray individuals and of a swarm of Daphnia magna preferentially preyed upon the strays; the resulting risk to the strays increased with swarm density (a leads to c leads to e in Fig. 1). This applied also to situations with constant swarm numbers but varied density (a leads to b, d leads to e). The results from two experiments with equal swarm density (b/e, c/d) suggest selection to be affected also by swarm number and/or volume.
The influence of olfactory and visual prey stimuli on the feeding behaviour of toads was studied as well as their response to lasting olfactory cues. A further aim was to find simple methods for testing olfactory responsiveness in anurans. Subjects were 8 adult specimens of the European species Bufo calamita (natterjack) kept in captivity one year at least. The results point to the rôle of olfaction in these animals.
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Initial maternal responsiveness as a function of varying pup stimuli was assessed in primiparous Long-Evans rats. Pups were removed during parturition and the dams tested beginning 24 hr later. These dams were most likely to respond maternally towards newborn (0-2-day-old) rat pups (100%) and 6-8-day-old hamsters, which are the size of newborn rats (83.3%). In contrast, dams were significantly less likely to respond maternally towards newborn hamsters (50%) and 8-10-day-old rats (16.7%), pups which are half as large and twice as large, respectively, as newborn rats; indeed, dams were likely to attack these pups (33.3% and 25%, respectively). The maternal response (less than or equal to 1 hr) to dead newborn rats was similar to that towards live newborn rats, except that fewer dams retrieved dead pups rapidly (less than or equal to 1 min). Cesarean-delivered dams did not display higher maternal responsiveness towards 0-2 than towards 8-10-day-old rats. Further, whereas no parturition-experienced dam displayed infanticide towards newborn rats, 21.9% of primiparous Cesarean-delivered dams did. Thus, the exogenous and/or endogenous stimuli associated with parturition enhance selective maternal responsiveness and diminish infanticide towards pups the size of newborn rats.
Flock-foraging and the role of white plumage in gulls and other seabirds have been the subject of much debate. At first sight it seems that competition within the flock would render flock formation against the interest of the bird who finds the fish school, as the fish must then be shared with birds joining the flock. However, it is also possible that flock formation is neutral or even beneficial to the individual members, including the bird that found the fish (the 'first finder'). Here we show that the fishing success of individual black-headed gulls, Larus ridibundus, increases with flock size up to at least eight birds. Part of the reason is that the fish school is more vulnerable when attacked by several gulls. The first gull to reach a fish school therefore benefits from being joined by others, and conspicuous white upper parts in gulls may act as a means of attracting other gulls to the flock and hence improving hunting success.
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The structure of relationships between the neighboring species of ants is characterized by great variability. What happens when particular individuals meet - depends upon considerable differences between individual behaviors of ants and a number of variable factors determining the actual emotional state of the workers. From these factors, it is the general structure of forces between the nests that changes slowest, and may be responsible for reaching temporary stabilization of the interspecific relationships. Invariable hierarchical structure between the species occurs very rarely: when there is an enormous supremacy of one of the species.
Gobiomorus dormitor success in capturing prey, cichlids, poeciliids and atherinids, is correlated with low luminance. Both prey and predator populations inhabiting rocky areas in Lake Jiloa, Nicaragua shift to deeper water during the dry season when luminance is greater. Predator and prey populations are also deeper over bright sandy areas than over rocks. Predators, during the middle of the day, attack prey significantly less in water above 3 m than in water between 3-12 m, but there is a significant increase in the number of attacks occurring above 3 m at twilight. The predator becomes more active, and the prey disappear into holes at twilight. These data suggest that conclusions concerning the importance of light in structuring the community and behavior of marine fishes can be generalized to tropical freshwater systems.
Predatory behaviour of the carnivorous marine pteropod mollusk Clione limacina is normally induced by contact with prey. In the absence of prey, a similar behaviour can be induced by injection of serotonin (5-HT) or its precursor, L-5-hydroxytroptophan (5-HTP). It consists of non-stop fast swimming, rapid extrusions of cephaloconi and other components of the actual prey capturing. Neuronal correlates of this phenomenon were investigated using histofluorescence and intracellular recordings. Prior to treatment with 5-HTP only green fluorescence of catecholamines has been revealed. In the CNS and periphery of 5-HTP-injected hunting animals yellow fluorescence of 5-HT is present as well. In isolated pedal ganglia 5-HTP induces characteristic changes in the activity of the swim generator neurones. An initial intermittent fictitious swimming of these neurones has been changed to sustained swimming of a higher frequency and enhanced spiking per cycle. Changes in activity of 5-HT-producing pedal neurones are also described.
The effects of central infusion of naloxone into the midbrain periaqueductal gray (PAG) upon predatory attack behavior in the cat were studied in 12 cats. Initially, quiet biting attack was elicited by electrical stimulation of sites within the lateral hypothalamus using monopolar electrodes. Then cannula-electrodes were implanted into sites within the PAG from which electrical stimulation facilitated or suppressed the attack response. Following identification of modulatory sites within the PAG, naloxone (1.0 micrograms/0.5 microliter) was microinjected into those sites and the effects upon hypothalamically elicited attack were assessed. At nine of twelve sites in the PAG where suppression was obtained, administration of naloxone served to block those effects. Similarly, at six of eight facilitatory sites within the PAG, naloxone also blocked the modulatory effects of PAG stimulation. However, vehicle (isotonic saline) alone did not alter the modulatory effects of PAG stimulation. Administration of DAME (250 ng/0.3 microliter) into PAG modulatory sites in four cats, two which facilitated and two that suppressed the attack response, reversed the effects of naloxone at these sites. These results demonstrate that opioid peptides within the PAG play a complex role in the expression of predatory attack behavior in the cat.
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Prey attack behavior was studied in two species of garter snakes (Thamnophis sirtalis and T. radix). Newborn, ingestively naive, and experienced snakes had their tongues severed surgically, while control groups retained their tongues. Attack latency, tongue flick frequency and an orientation-interest measure were recorded for each subject on responses to extracts prepared from species-characteristic prey. Feeding, as well as responses to prey extracts, were found to be suppressed almost totally in the tongueless naive snakes. A detongued adult, however, readily ate although its behavior was abnormal. Temporary blind and anosmic conditions did not have a significant effect on response rates of the tongueless or control groups. While importance of the tongue-Jacobson's organ system is demonstrated, the length of tongue removed and presurgery experience are important factors.