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At least 91 records · Page 5Linked to original sources
PubMed1984

Effects of search cost on foraging and feeding: a three-component chain analysis.

An experiment determined whether pigeons minimize number of key pecks per food delivery and maintain their baseline intake of food while key pecking on a three-component chain schedule. Pigeons at either 80% or 100% body weight obtained all their food during baseline and contingency sessions. During baseline sessions, pecks on the left and center keys had no consequences; each peck on the right key activated the feeder. During contingency sessions, pigeons key pecked on a three-component chain schedule simulating components of a foraging chain. In the search component either 3, 9 or 15 key pecks (varied parametrically across blocks of sessions) on the left key produced a stimulus on the middle key, indicating an encounter with either the low-cost prey (3 key pecks) or an equally probable high-cost prey (21 key pecks). In the procurement component the pigeon pecked either: (a) the left key once, thus returning to the search component, or (b) the middle key either 3 or 21 times, which activated the right response key. In the handling component one peck on the right key operated the feeder. The pigeons always procured the low-cost prey and minimized the number of key pecks per hopper by procuring the high-cost prey when the search-cost ratio was high (15 key pecks) but not when it was low (3 key pecks). All pigeons maintained their baselines of eating during contingency sessions by key pecking more frequently and eating more efficiently. The 80% body-weight birds produced higher overall rates of key pecking and eating. These results have implications for ecological theories of optimal foraging and for psychological theories of learned performance.

Animals↗
PubMed1975

Ethological studies in the ant Tetramorium caespitum Mayr. II. Interspecific relationships.

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.

Animals↗
PubMed1979

The effect of luminance upon the distribution and behavior of the Eleotrid fish Gobiomorus dormitor, and its prey.

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.

Animals↗
PubMedDate not supplied

[The neuronal correlates of the serotonin-dependent behavior of the pteropod mollusk Clione limacina].

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.

5-Hydroxytryptophan↗
PubMed1991

Enkephalinergic involvement in periaqueductal gray control of hypothalamically elicited predatory attack in the cat.

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.

Aggression↗
PubMed1985

The control exerted by the substantia nigra on the quiet biting attack elicited by hypothalamic stimulation in the cat.

The effects of substantia nigra (SN) (pars compacta) stimulation on the quiet biting attack evoked by hypothalamic activation in the cat were studied. The measure of the aggressive behavior was the latency of the biting which did not greatly change from one animal to another when hypothalamic stimulation was performed with the same parameters. Concurrent activation of the SN determined an inhibitory effect on the studied behavior in the form of an increase in the biting latency or loss of the attack pattern. The inhibitory role of the SN on predatory attack behavior is discussed.

Aggression↗
PubMed1975

Role of the tongue and senses in feeding of naive and experienced garter snakes.

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.

Animals↗
PubMed1984

Mouse-killing in Sprague-Dawley rats: effects of lighting conditions.

Sixteen male Sprague-Dawley rats were studied in artificial daylight and in red light for mouse-killing. Fifty percent of the rats killed mice. Killing varied, however, considerably: only seldom did it occur on consecutive days. More killing occurred during tests in red light than in artificial daylight. In red light, the mean latency between confrontation of the rat with the mouse and the killing was gradually shortened but not in daylight.

Animals↗
PubMed1992

Oral estrogen retains potency as an aversion agent in eggs: implications to studies of community ecology and wildlife management.

The first of two experiments with laboratory rats demonstrated that oral estrogen (17 alpha-ethinylestradiol) can remain in the albumen of eggs at room temperature for up to 8 days with undiminished capacity to produce conditioned taste aversion. The second experiment showed that estrogen remains potent in the yolk of eggs for at least 4 days. There is now greater assurance that egg prey placed into the field will induce reliable CTA among mammalian predators. Community ecologists interested in such processes as competitive release and the responses of prey populations to reduced predation upon their eggs can selectively factor predation out of field experiments without the need for physically excluding predators. Wildlife biologists interested in reducing predation upon the eggs of endangered species now have greater assurance that estrogen-treated egg baits will suppress predation in a more cost-effective manner and with less likelihood of discrimination between treated eggs and those of endangered species.

Animals↗
PubMedDate not supplied

Stunning whales.

Explore the source record for details and available documents.

Animals↗
PubMed1979

The influence of prey experience on movement pattern preference in Salamandra salamandra (L.).

Groups of juvenile Salamandra salamandra were raised selectively with different types of prey. The influence of these conditions on the movement pattern preference was studied during the first six months after metamorphosis. Responses to a black horizontal bar moving continuously or stepwise at step frequencies between 0.25 and 8 steps/s were tested. The differently raised groups showed significant differences in their respective preference for stimulus movement patterns which corresponded with the movement pattern of their food. At the same time, superimposed upon this learning process, a general increase in the relative efficiency of continuous stimulus movement with regard to stepwise stimulus movement could be observed.

Animals↗
PubMed1978

Neonatal lamb losses due to feral pig predation.

An investigation into causes of low lamb marking percentages was made on a property in north-west New South Wales from 1971 to 1975. Investigations revealed that from 11 to 70% of the ewes in lamb were losing all their lambs. Observations suggested that feral pig predation was a factor in the perinatal loss. In 1975, 2 groups of ewes were placed in adjoining paddocks prior to lambing. Feral pigs were excluded from one paddock for most of lambing by means of an electric fence. In this paddock, 117% of lambs were marked compared with 80% in the adjoining paddock. It was estimated that in 1975 over 600 lambs were killed by feral pigs from 1,422 ewes lambing in paddocks with feral pigs. The problems involved in the diagnosis of feral pig predation are discussed.

Animal Population Groups↗