Predator Stimulus Research Articles

The anxiety/defense test battery: Influence of gender and ritanserin treatment on antipredator defensive behavior

The anxiety/defense test battery has been developed to measure defensive reactions in laboratory rats to both direct exposure to, and stimuli associated with, a natural predator, the domestic cat. The present investigation confirmed earlier findings with each test providing a distinct behavioral profile following exposure to predator stimuli. In addition, the data showed a consistent gender difference in a number of these behavioral measures, indicating that females are more defensive than males. These effects included reliably higher levels of cat avoidance and crouching, with lower levels of transits, lying and drinking for cat-exposed females. Similarly, females exposed to a cat odor stimulus showed a reliably higher level of stretch attend and flat back approach behaviors (risk assessment) towards the stimulus block. The 5-HT 2 antagonist, ritanserin, failed to provide significant indication of anxiolytic activity, and had minimal influence on antipredator defensive behavior. An important exception to this profile was a reliable decrease in stretch attend behavior to a cat odor stimulus in females but not males. Overall, these findings suggest a complex relationship between gender, antipredator defensive behavior, and anxiolytic drug treatment.

Video image recognition by the jumping spider, Maevia inclemens (Araneae: Salticidae)

Jumping spiders of the family Salticidae have well developed eyes, which mediate their highly stereotyped predatory and commnicative behaviour. Experimental studies presented here provide behavioural evidence that salticids are capable of perceiving televised (video) images. Juvenile and sexually mature individuals of the dimorphic jumping spider, Maevia inclemens (Walckenaer), were tested in V-maze choice test and behavioural chambers where they were allowed to view images of videotaped prey and spiders presented on Sony Watchman micro-television unuits. Results from this study suggest that jumping spiders interpret video images as real, because: (1) spiders did not discriminate between live prey and its simulateously presented video image; and (2) they behave appropriately when presented with televised images of prey insects (e.g. stalk and attack televised prey), conspecifics (e.g. courtship and sexual receptivity behaviour directed toward televised conspecifics) and heterospecific jumping spider species (e.g. retreat from predator stimulus). These observations support a previous estimate, of low critical flicker fusion frequency values in this group, and enable the development of a powerful new method for the study of animal behaviour.

Chemical detection of predators by a lizard, the broad‐headed skink (Eumeces laticeps)

AbstractThe scincid lizard Eumeces laticeps is shown experimentally 1) to be capable of detecting integumentary chemical stimuli from two congeneric species of snakes that are sympatric predators of lizards and 2) to discriminate these chemical stimuli from similar ones derived from a sympatric snake that does not eat lizards and from a common insect food species. The experimental technique employed in this study, i.e., presentation of odorants on cotton‐tipped applicators, allows rapid assessment of responses to predator odors and is suitable for a survey of these responses in a wide variety of lizards. The skinks showed significantly higher tongue‐flicking rates in response to odors of snake predators and food odors (cricket) than to odors of a snake that does not eat lizards and an odorless control. Tongue‐flick attack score, a measure of response strength to chemical stimuli from food, was much greater for cricket stimuli than for the predator stimuli. Significantly more lizards bit applicators bearing cricket stimuli than bit applicators bearing any of the other stimuli. After biting applicators bearing predator odors, the lizards quickly released. In contrast, they frequently maintained a grasp after biting applicators bearing cricket odors. A few preliminary speculations are made regarding ecological factors that may affect responsiveness by lizards to predator odors.

Early Warning Lowers Risk of Stonefly Predation for a Vulnerable Mayfly

Behavior of Baetis bicaudatus (Ephemeroptera; Baetidae) was video taped in a western Colorado, USA stream to identify the specific stimuli eliciting noncontact responses to predatory stoneflies (Kogotus modestus; Plecoptera; Perlodidae). In situ behavioral and feeding trial experiments were also conducted to assess the effect of removal of Baetis cerci on these responses to predators, on measured reactive distances, and on the vulnerability of Baetis to stonefly predation. Predatory stimuli tested included live stoneflies (tethered and untethered), stonefly models (plasticized), excised fresh stonefly antennae, and wires. Intact Baetis primarily turned their cerci (tail curl behavior) with similar frequencies toward live or model stoneflies that were between 1 and 2 cm downstream, and primarily moved when stoneflies were within 1 cm even before contact. Removal of Baetis' cerci reduced the frequency of tail curl responses and the reactive distance, but increased the frequency of movement responses to noncontact with Kogotus. Neither intact nor cerciless Baetis showed much response to Kogotus antennae and wires. These results suggest that stimuli associated with the whole stonefly, such as visual or more probably hydrodynamic cues, cause Baetis tail curl behavior. However, movement behavior was uniformly high after contact with all predator treatments, and the pattern of movement (swim, drift or crawl) varied with predator stimulus, suggesting that Baetis can discriminate live or model Kogotus, Kogotus antennae, and wires using chemotactile or tactile cues. Removal of Baetis cerci resulted in increased encounter rates (contact) with live, untethered Kogotus, higher capture success, and greater predation rates than on intact Baetis. When touched by all predator treatments, Baetis usually swam, a behavior that stimulates stonefly attacks, but after noncontact tail curl responses, Baetis most often remained stationary. Thus, cerci were apparently effective as an early warning system, enabling Baetis to detect Kogotus before contact, thereby reducing the incidence of dangerous swimming escape behavior, and the susceptibility to predation.

Why Do Ephemerella Nymphs Scorpion Posture: A "Ghost of Predation Past"?

The behavior of intact Ephemerella infrequens (Ephemeroptera, Ephemerellidae) and Ephemerella with cerci amputated was observed in response to encounters with live predaceous stoneflies (Megarcys signata, Plecoptera: Perlodidae), tethered-live and tethered-model predators, freshly excised stonefly antennae, and thin wires. The incidences of defensive posturing (scorpion posture), movement (crawl, swim, drift) and freezing (no response, stop) behavior were video-taped in response to these predatory stimuli. Scorpion postures occurred with significantly higher frequency when Ephemerella was touched by live and model Megarcys than by Megarcys antennae and wires, with no differences between the two former or the two latter treatments. Frequency of posturing was not altered by prey orientation toward or away from predators or by direction of predator approach with respect to current (upstream, downstream, or beside prey). Thus, hydrodynamic cues associated with live and model Megarcys rather than simple tactile, chemical or visual cues are probably most important in stimulating Ephemerella to scorpion posture. Removal of Ephemerella cerci resulted in a decreased incidence of scorpion posturing, and modification of frequencies of movement and freezing behaviors with predator-prey orientation. These results suggest that cerciless mayflies may have impaired or altered sensory systems. However, cercal removal did not increase Ephemerella's risk of predation, since numbers of intact and cerciless prey consumed during predation trials did not differ. Gut content analysis of Megarcys showed that they were size selective on smaller Ephemerella, which are known to scorpion posture with significantly lower frequency than large Ephemerella. We speculate that the posture is an evolutionary relict, a ghost of predation past, that is not as effective in smaller individuals, which are also softer-bodied and have smaller spines. Present-day preference for small Ephemerella or other mayfly species over large Ephemerella may be attributed to the historical effectiveness of the scorpion posture, long prey handling times, difficulty in prey capture, or absence of an appropriate behavioral attack stimulus. None of these factors was affected by removal of cerci.

Feeding under predation hazard: response of the guppy and Hart's rivulus from sites with contrasting predation hazard

Populations of guppies, Poecilia reticulata and Hart's rivulus, Rivulus harti, in Trinidad experience different levels of predation hazard from piscivorous fish. Those from the larger rivers (“downstream sites’) experience chronically high predation hazard, while those from headwater streams (“upstream sites”) have few predators. Guppies and Hart's rivulus, collected from downstream and upstream sites, were assayed for their feeding rate in the presence and absence of predators. We defined tenacity as the ratio of the feeding rates in the presence and absence of a predator stimulus. Thus, tenacity expresses the degree to which the forager maintains its feeding rate when a predator stimulus is present. Previous work by Seghers (1973) showed that non-feeding guppies from downstream sites responded more strongly to predators than did guppies from upstream sites. Based on this, we initially hypothesized that fish from downstream sites would show lower tenacities than fish from upstream sites. However, we found the opposite in every case. When confronted with a predator stimulus, guppies and Hart's rivulus from downstream sites fed at consistently greater rates and displayed greater tenacities than did those from upstream sites. These differences were found in experiments using both live and model predators. The results suggest that upstream fish readily trade off feeding for hiding and avoiding predation hazard, a likely response when predators appear infrequently, while downstream fish appear to be selected for boldness and tenacity while foraging under chronically high hazard.

A neural model of interactions subserving prey-predator discrimination and size preference in anuran amphibia

The model described is an extension of a previous model of the optic tectum (Arbib & Lara, 1982; Lara, Arbib & Cromarty, 1982; Lara & Arbib, 1982) and takes into consideration anatomical, physiological and behavioral studies in anurans, as well as earlier modelling efforts (Ewert & Von Seelen, 1974; Didday, 1976). Computer simulations were conducted to analyze how interactions among retina, optic tectum and pretectum may give frogs and toads the ability to discriminate between prey and predator stimuli. Results from simulations have allowed us to reproduce empirical observations, to suggest new experiments, and to postulate what neural mechanisms might be involved in some phenomena related to prey-catching orienting behavior, with direction invariance of prey-predator recognition being a consequence of tectal architecture, and size preference and response latency depending on the motivational state of the animal.

Toddler peer interaction in mixed age groups

The present research examined whether children's ability to impute false belief is overridden or impaired by content that activates an early-developing, prepotent motivational system: predator avoidance. In three studies, children aged 3 to 8 years completed variants of a false-belief test, including analogous predator-avoidance and playmate-avoidances scenarios, in which passing the test meant having the focal character get caught by the pursuer. The proportion of correct answers in the playmate-avoidance scenario was reliably greater than in the predator-avoidance scenario, though this effect largely dissipated by 7 to 8 years of age. Enhanced predatory stimuli significantly increased the frequency of false-belief errors in the predator-avoidance scenario (Study 3). Analysis of children's justifications revealed that predator-avoidance false-belief errors were overwhelming motivated by a desire for the prey to avoid the predator (Study 2). The predator-avoidance effect was not an artifact of children generally performing better in playmate than predator–prey scenarios (Studies 1 and 3), the predator-avoidance scenario simply evoking strong emotions (Study 3), or differences between children in their knowledge of predator–prey relationships (Study 1) or executive-function abilities (Study 2). Findings support the hypothesis that activation of the predator-avoidance system generates prepotent response patterns that impair or override full consideration of the mental states of the prey characters in false-belief stories.

Influence of Social and Predatory Stimuli on the Air-Breathing Behavior of the African Clawed Frog, Xenopus laevis

Air breaths in undisturbed laboratory and pond groups of the aquatic African clawed frog, Xenopus laevis, Pipidae, are significantly clustered in time or synchronized in a manner similar to that of some air-breathing fishes. Breaths of isolated frogs occur at higher rates and were non-synchronous suggesting that a social component functions in the control of air-breathing behavior in this species. In several tests, disturbance (aerial, surface, and sub-surface) of pond or laboratory groups ofX. laevis increased the level of synchrony and temporarily decreased air-breathing rate. In X. laevis, air breathing may, if socially elicited, occur independently of the need for gas exchange or be postponed by disturbance.