Mechanistic research on antipredator behavior focuses on identifying the causes and consequences ... more Mechanistic research on antipredator behavior focuses on identifying the causes and consequences of how prey cope with predators. The perceptual aspects of predator recognition are emphasized, focusing on the olfactory, auditory, and visual recognition cues used to identify predators. Predator recognition can result from learning to associate a predator with a threatening circumstance, a process that enhances survival and compensates for historical inconsistencies in predator encounters that have not acted as sources of natural selection. If predator configuration and the circumstances of predator encounters have been consistent in the evolutionary time frame, then natural selection can shape the evolution of predator recognition. Relaxed selection from predators has different effects on the persistence of innate predator recognition depending on the complexity of perceptual integration.
The 41 articles selected for this book cover a wide range of topics, beginning with discussions o... more The 41 articles selected for this book cover a wide range of topics, beginning with discussions on the biological aspects governing the origin of man and ending with studies of urban sociology and physical ecology. Although this book is intended primarily for students of anthropology and ecology, there are many interesting points brought out by the various contributors that should interest both artists and designers who are concerned with the technological predicament of mankind. One underlying aspect I sensed is the caution expressed by many of the contributors about man’s biological and social attachment to technological innovations, of which many may have deleterious by-products. Several of the contributors suggest that with the aid of technology, man is simplifying the ecosystem in a maladaptive way, using substitutes that increase the fragility of the system. More insidious, however, is the problem of waste management in industrial countries that leads to the production of mutagenic chemical substances by air and water pollution. Combined with this problem is wholesale destruction of the present floral and faunal ecosystems by cultivation, deforestation, land drainage and migratory blockage. The articles are arranged in three sections: I. Biological Anthropology, 11. Human Prehistory and 111. Cultural Anthropology. In the first section, Newell’s ‘Crisis in the History of Life’ discusses the extinction of a wide range of species-groups in relatively short geological time periods, possibly caused by climatic disruption of the biotope. More recent extinction of large mammals is attributed to upper Paleolithic man. Other articles in this section include new fossil evidence of man’s evolution by Howells and Simons and discussions of natural selection and genetic variability by Crow and by Dobzhansky. Both of the latter contributors suggest that man should try to lower the spontaneous mutation rate caused by environmental factors. But further, technology has relaxed the normal selection pressures, which further enhance the sustenance of genetic defects. The effect of crowded urban environments is examined in Singh’s ‘Urban Monkeys’. This study of Asian macaques living in cities indicates that novel environments increase exploratory behavior and tolerance to new situations. Articles in the second section include Washburn’s ‘Tools and Human Evolution’, a discussion of the possible evolutionary role played by early tool-using Hominids. Washburn makes an important point that the behavioral changes brought about by successful tool-making cultures improved the selection toward greater intelligence. Other articles in this section are concerned with more traditional studies of man’s prehistory and the development of small permanent settlements and towns from earlier Neolithic sites. Adams presents a hypothesis in ‘The Origin of Cities’ that suggests that the aiversity of human experience provided by the urban environment, such as religious and craft activity, rather than available food surpluses accounts for the rapid growth and stability of ancient cities. In examining one particular city, Millon presents evidence that TeotihuacBn, Mexico’s largest pre-Columbian city, has structural features not unlike those of classical cities. Examples of design parallelism should interest the architect because they infer natural human preferences. The third section emphasizes both the traditional concerns of cultural anthropology and new areas of interest in contemporary societies. Rappaport’s ‘The Flow of Energy in an Agricultural Society’ examines the careful resource management of a New Guinean tribe and compares it with modern agricultural societies, which have simplified their energy sources to the point where they are subject to vast and potentially dangerous political and economic changes’ Cook‘s ‘The Flow of Energy in an Industrial Society’.
Individual predators differ in the level of risk they represent to prey. Because prey incur costs... more Individual predators differ in the level of risk they represent to prey. Because prey incur costs when responding to predators, prey can benefit by adjusting their antipredator behavior based on the level of perceived risk. Prey can potentially assess the level of risk by evaluating the posture of predators as an index of predators' motivational state. Like other prey species, humans might evaluate predator body posture as a prominent cue for assessing danger. We tested whether human participants adjusted their visual attention based on the postures of predators by presenting participants with photographic arrays of predators (lions) that varied in postures while we recorded the participants' gaze behavior. The participants searched for a standing lion (representing a high-risk target) among an array of reclining lions (representing low-risk distractors) or searched for a reclining lion among an array of standing lions. They also searched through similar arrays consisting of non-threatening prey (impalas) standing or reclining, rather than predators. Participants detected standing lions and impala faster than reclining lions and impala. Surprisingly, they detected standing lions at similar latencies as standing impala. They detected the reclining lions and impala more slowly because they spent more time looking at the standing lion and impala distractors and looked at more of those distractors. These results show that upright animals, regardless of whether they are predators or prey, attract attention in humans, and this could allow humans to rapidly evaluate predatory threats or the flight readiness of hunted game.
Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistor... more Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistoric cave and mobiliary art. Two experiments examined the saliency of snake scales and leopard rosettes to infants that are perceptually analogous to these patterns. Experiment 1 examined the investigative behavior of 23 infants at three daycare facilities. Four plastic jars (15 × 14.5 cm) with snake scales, leopard rosettes, geometric plaid, and plain patterns printed on yellowish-orange paper inside were placed individually on the floor on separate days during playtime. Fourteen 7-15-month-old infants approached each jar hesitantly and poked it before handling it for five times, the criterion selected for statistical analyses of poking frequency. The jars with snake scales and leopard rosettes yielded reliably higher poking frequencies than the geometric plaid and plain jars. The second experiment examined the gaze and grasping behavior of 15 infants (spanning 5 months of age) seated on the laps of their mothers in front of a table. For paired comparisons, the experimenter pushed two of four upright plastic cylinders (13.5 × 5.5 cm) with virtually the same colored patterns simultaneously toward each infant for 6 s. Video recordings indicated that infants gazed significantly longer at the cylinders with snake scales and leopard rosettes than the geometric plaid and plain cylinders prior to grasping them. Logistic regression of gaze duration predicting cylinder choice for grasping indicated that seven of 24 paired comparisons were not significant, all of which involved choices of cylinders with snake scales and leopard rosettes that diverted attention before reaching. Evidence that these biological patterns are salient to infants during an early period of brain development might characterize the integration of subcortical and neocortical visual processes known to be involved in snake recognition. In older individuals, memorable encounters with snakes and leopards coupled with the saliency of snake scales and leopard rosettes possibly biased artistic renditions of similar patterns during prehistoric times.
California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against thei... more California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against their two predators, the northern Pacific rattlesnake (Crotalus viridis oreganus) and Pacific gopher snake (Pituophis melanoleucus catenifer). Two studies were used to examine individual variation in antisnake behavior as it might be affected by selection operating on arousability, fearfulness, and aggressiveness. In Study 1 the behavioral consistency of two litters of lab-reared juveniles was examined at two age periods during encounters with a caged gopher snake and domestic cat. Close-range investigation and tail flagging appeared to be governed by short-term motivational states that were not strongly correlated across age. Age correlations revealed that individual tendencies to throw substrate were relatively consistent for the snake and even more so for the cat. In Study 2, wild-caught adults were obtained from five sites where rattlesnakes and gopher snakes were abundant and from five sites where these snakes were rare or absent. Squirrels in a seminatural laboratory setting were given balanced presentations of a caged rattlesnake and gopher snake separated by 5 days. Snakes were recognized by all squirrels as potentially dangerous, irrespective of experience, age, and selective regime. Substrate throwing also was positively correlated for the two snakes in both groups of adults, indicating that level of aggressiveness is a consistent component of temperament not specific to species of snakes. Physiological arousal was not correlated strongly for the two snakes, but it was significantly lower in squirrels from sites where snakes were abundant. This suggests some specialization to reduce anxiety that possibly enhances tactical decision making.
Wild and urban bonnet macaques (Macaca radiata) were studied in southern India to record alarm ca... more Wild and urban bonnet macaques (Macaca radiata) were studied in southern India to record alarm calls during presentations of realistic models of spotted and dark leopards (Panthera pardus) and an Indian python (Python molurus). Recordings of alarm calls were made from members of four forest troops at feeding stations who observed brief and prolonged presentations of fully exposed spotted and dark leopard morphs and partially concealed views of the spotted morph. Four different forest troops were presented a slowly moving python near feeding stations. Two predator-inexperienced urban troops from the city of Bangalore were presented either the spotted leopard morph briefly or the python. Analyses of alarm calls revealed differences in acoustic structure, such as a lower harmonic to noise ratio, which can be interpreted as reflecting the level of perceived threat rather than predator type. Noisy alarm calls likely indicate high states of physiological arousal that might provide eavesdropping troop members with information useful for assessing the urgency of the predatory threat. Lack of alarm-call distinctiveness characterizing predator type is complemented by explicit contextual information in which alarm calling to leopards never occurred on the ground whereas nearly all initial python-elicited alarm calls were made by individuals on the ground monitoring the python. The alarm calls of Bangalore monkeys distinguished the leopard and python models, with the latter engendering the noisiest calls and immediate flight to trees. Such flight is unnecessary with the python and suggests that, without appropriate experience with pythons, bonnet macaques adopt less predator specific refuge-seeking behavior.
Rock squirrels (Spermophilus variegatus) from two sites in south central New Mexico, where prairi... more Rock squirrels (Spermophilus variegatus) from two sites in south central New Mexico, where prairie (Crotalus viridis viridis) and western diamondback (Crotalus atrox) rattlesnakes are common predators, were assayed for inhibition of rattlesnake venom digestive and hemostatic activities. At statistically significant levels rock squirrel blood sera reduced the metalloprotease and hemolytic activity of venoms from C. v. viridis and C. atrox more than venom from an allopatric snake species, the northern Pacific rattlesnake (Crotalus oreganus). In contrast, general proteolytic activity of venom from C. oreganus was inhibited more by S. variegatus serum defenses than activity of venom from sympatric snakes. For all three venoms, incubation with squirrel sera increased the level of fibrinolysis over venom-only treatments. These results suggest that rock squirrels (S. variegatus) can defend against metalloproteases and other proteases after envenomation from at least two of five rattlesnake predators they might encounter. However, there were statistically significant differences between general proteolytic activity and fibrinolytic activity of C. v. viridis and C. atrox venom, suggesting that rock squirrels might be differentially vulnerable to these two predators. The hypothesis that prey resistance influences snake venom evolution in a predator-prey arms race is given further support by the previously cryptic variation in venoms detected when assayed against prey defenses.
Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among othe... more Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among others, in response to predators. The nature of this response is variable, with animals reacting more strongly in situations of increased vulnerability. Our research described here is the first formal study to investigate night-time antipredator behaviour in any species of elephants, Asian or African. We examined the provocative effects of elephant-triggered tiger and leopard growls while elephants attempted to crop-raid. Tigers opportunistically prey on elephant calves, whereas leopards pose no threat; therefore, we predicted that the elephant response would be reflective of this difference. Elephants reacted similarly cautiously to the simulated presence of felids of both species by eventually moving away, but differed markedly in their more immediate behavioural responses. Elephants retreated silently to tigergrowl playbacks, whereas they responded with aggressive vocalizations, such as trumpets and grunts, to leopard-growl playbacks. Elephants also lingered in the area and displayed alert or investigative behaviours in response to leopard growls when compared with tiger growls. We anticipate that the methods outlined here will promote further study of elephant antipredator behaviour in a naturalistic context, with applications for conservation efforts as well.
Wild bonnet macaques (Macaca radiata) have been shown to recognize models of leopards (Panthera p... more Wild bonnet macaques (Macaca radiata) have been shown to recognize models of leopards (Panthera pardus), based on their configuration and spotted yellow coat. This study examined whether bonnet macaques could recognize the spotted and dark melanic morph when partially concealed by vegetation. Seven troops were studied at two sites in southern India, the Mudumalai Wildlife Sanctuary and the Kalakad-Mundanthurai Tiger Reserve. The forequarters and hindquarters of the two leopard morphs were presented from behind thick vegetation to individuals at feeding stations 25 m away. Flight reaction times and frequency of flight were obtained from video for only those individuals who oriented towards the models prior to hearing alarm calls. Bonnet macaques exhibited faster reaction times and greater frequency of flight after looking at the spotted morph's forequarter than after looking at either its spotted hindquarter or the dark morph's forequarter. The hindquarter of the dark morph was ignored completely. Artificial neural network modeling examined the perceptual aspects of leopard face recognition and the role of spots as camouflage. When spots were integrated into the pattern recognition process via network training, these spots contributed to leopard face recognition. When networks were not trained with spots, spots did not act as camouflage by disrupting facial features.
Sleep results in a decrease in alertness, which increases an animal's vulnerability to predation.... more Sleep results in a decrease in alertness, which increases an animal's vulnerability to predation. Therefore, choice of sleeping sites would be predicted to incorporate predator-avoidance strategies. The current study, conducted in two national parks in southern India, examined the behaviors adopted by bonnet macaques (Macaca radiata) to reduce the risk of being preyed upon while sleeping. Bonnet macaques from an urban setting with a low predatory risk were included for comparison. The physical characteristics of the sleeping sites in the forest corresponded with features that were most difficult for predators to access; bonnet macaques selected emergent trees with high boles near human settlements. These trees typically overhung water. Within the canopy, individuals slept in huddled subgroups near the terminal ends of branches, preferentially selecting branches over water. Subgroups were generally composed of members of the same age and sex, which likely promoted social bonding. Adult males and females with infants selected branches higher than members of other age and sex categories. The lateral distances of individuals along branches from the main trunk were similar across demographic categories. The size of a subgroup appeared to be limited by the weight a branch could support; lateral distances were maintained by regulation of mean subgroup weight, with heavier individuals forming smaller subgroups. The urban troop slept on the top of a building. Subgroup compositions at the urban site were similar to those at the forest sites. However, subgroup size, not restricted by branch fragility, resulted in larger subgroups than those found in the forest. Our results indicate that bonnet macaques adopted a suite of behaviors that reduced their risk of being preyed upon at night by selecting sleeping sites that minimized predator encounters and by selecting the safest locations within the canopy.
We thank the Forest Department of Tamil Nadu for granting us permission to conduct research in th... more We thank the Forest Department of Tamil Nadu for granting us permission to conduct research in the Kalakad-Mundanthurai Tiger Reserve and the Mudumalai Wildlife Sanctuary and its staff for facilitating our research. We also thank Lynne Isbell and Donald H. Owings for their comments that improved this article. Finally, we thank our field assistants. Anil Kumar, M. Siddhan, and V. Yashoda, for their contributions in data collection and Chantal Stoner and Michele Tupin for their assistance in quantifying the videorecordings.
This study examined the perceptual features of leopards (Panthera pardus) used as recognition cue... more This study examined the perceptual features of leopards (Panthera pardus) used as recognition cues by bonnet macaques (Macaca radiata) at three sites in southern India. Two of these sites were protected deciduous forest areas, the Mudumalai Wildlife Sanctuary and the Kalakad-Mundanthurai Tiger Reserve. The third study site was a predator-rare urban setting, Bangalore city. Four models were presented for 10-s intervals: (1) upright spotted leopard in a stalking pro le with its head facing the subjects; (2) the same spotted model presented upside down; (3) a dark-brown leopard model with the same con guration as the spotted model; and nally (4), the dark-brown model presented upside down. The upright models characterized the two leopard morphs found in the wild-spotted and dark melanic. Inverted presentations of the spotted model examined the effects of the same con guration in an incongruous position to document whether leopard spots were still recognized. Differences between models were examined using alarm calls and ight elicitation as indices of fear. The spotted upright model was found to be the most feared, followed by the spotted upside-down model, the dark upright model, and nally the dark upside-down model. Analysis of when individuals looked at troop members to assess risks revealed that the spotted upright and dark upsidedown models engendered signi cantly lower frequencies of information seeking; the upright model typically engendered immediate ight and the dark upside-down model was generally ignored. The spotted upside-down model and the dark upright model engendered high rates
Young animals are known to direct alarm calls at a wider range of species than adults. Our field ... more Young animals are known to direct alarm calls at a wider range of species than adults. Our field study examined age-related differences in the snake-directed antipredator behavior of infant, juvenile, and adult white-faced capuchin monkeys (Cebus capucinus) in terms of alarm calling, looking behavior, and aggressive behavior. In the first experiment, we exposed infant and juvenile white-faced capuchins to realistic-looking inflatable models of their two snake predators, the boa constrictior (Boa constrictor) and neotropical rattlesnake (Crotalus durissus) and a white airplane as a novel control. In the second experiment, infants, juveniles, and adults were presented photographic models of a coiled boa constrictor, rattlesnake, indigo snake (Drymarchon corais), a noncapuchin predator, and a white snake-like model. We found that antipredator behavior changed during the immature stage. Infants as young as 4 months old were able to recognize snakes and display antipredator behavior, but engaged in less snake-model discrimination than juveniles. All age classes exhibited a lower response to the white snake-like model, indicating that the absence of color and snake-scale patterns affected snake recognition. Infants also showed a higher level of vigilance after snake-model detection as exhibited by a higher proportion of time spent looking and head cocking at the models. Aggressive antipredator behavior was found in all age classes, but was more prevalent in juveniles and adults than infants. This study adds to the knowledge of development of antipredator behavior in primates by showing that, although alarm calling behavior and predator recognition appear at a very young age in capuchins, snake-species discrimination does not become apparent until the juvenile stage. Am. J.
Wild bonnet macaques (Macaca radiata) were studied in southern India to assess their ability to d... more Wild bonnet macaques (Macaca radiata) were studied in southern India to assess their ability to discriminate non-venomous, venomous and predatory snakes. Realistic snake models were presented to eight troops of bonnet macaques at feeding stations and their behavior was video-recorded 3 min before and 3 min after snake exposure. Snakes presented were: (1) venomous Indian cobra (Naja naja) displaying an open hood with ÔeyespotsÕ; (2) venomous common Indian krait (Bungarus caeruleus); (3) non-venomous green keelback (Macropisthodan plumbicolor); (4) non-venomous rat snake (Ptyas mucosus); and (5) Indian python (Python molurus) which preys on macaques. Latencies to detect and react to the snakes were evaluated to determine initial responsiveness. Longer-term assessment was measured as the percentage of time individuals looked at the snakes and monitored the activity of nearby individuals before and after snake detection. All snake models engendered caution and maintenance of a safe distance. Alarm calling occurred only during python presentations. The cobra engendered a startle response or running in the largest percentage of individuals after its detection, whereas the rat snake and python elicited bipedal standing or ambulating to monitor the snakes. We also examined the influence of age on snake recognition. Juveniles and subadults looked at the cobra, krait, and python for a larger percentage of time than adults did; albeit, adults looked at the python substantially longer than at the other snakes. Age differences in behavior suggest that, with the exception of the python, repeated experience with snakes in the wild moderates excitability, consistent with the likely threat of envenomation.
Mechanistic research on antipredator behavior focuses on identifying the causes and consequences ... more Mechanistic research on antipredator behavior focuses on identifying the causes and consequences of how prey cope with predators. The perceptual aspects of predator recognition are emphasized, focusing on the olfactory, auditory, and visual recognition cues used to identify predators. Predator recognition can result from learning to associate a predator with a threatening circumstance, a process that enhances survival and compensates for historical inconsistencies in predator encounters that have not acted as sources of natural selection. If predator configuration and the circumstances of predator encounters have been consistent in the evolutionary time frame, then natural selection can shape the evolution of predator recognition. Relaxed selection from predators has different effects on the persistence of innate predator recognition depending on the complexity of perceptual integration.
The 41 articles selected for this book cover a wide range of topics, beginning with discussions o... more The 41 articles selected for this book cover a wide range of topics, beginning with discussions on the biological aspects governing the origin of man and ending with studies of urban sociology and physical ecology. Although this book is intended primarily for students of anthropology and ecology, there are many interesting points brought out by the various contributors that should interest both artists and designers who are concerned with the technological predicament of mankind. One underlying aspect I sensed is the caution expressed by many of the contributors about man’s biological and social attachment to technological innovations, of which many may have deleterious by-products. Several of the contributors suggest that with the aid of technology, man is simplifying the ecosystem in a maladaptive way, using substitutes that increase the fragility of the system. More insidious, however, is the problem of waste management in industrial countries that leads to the production of mutagenic chemical substances by air and water pollution. Combined with this problem is wholesale destruction of the present floral and faunal ecosystems by cultivation, deforestation, land drainage and migratory blockage. The articles are arranged in three sections: I. Biological Anthropology, 11. Human Prehistory and 111. Cultural Anthropology. In the first section, Newell’s ‘Crisis in the History of Life’ discusses the extinction of a wide range of species-groups in relatively short geological time periods, possibly caused by climatic disruption of the biotope. More recent extinction of large mammals is attributed to upper Paleolithic man. Other articles in this section include new fossil evidence of man’s evolution by Howells and Simons and discussions of natural selection and genetic variability by Crow and by Dobzhansky. Both of the latter contributors suggest that man should try to lower the spontaneous mutation rate caused by environmental factors. But further, technology has relaxed the normal selection pressures, which further enhance the sustenance of genetic defects. The effect of crowded urban environments is examined in Singh’s ‘Urban Monkeys’. This study of Asian macaques living in cities indicates that novel environments increase exploratory behavior and tolerance to new situations. Articles in the second section include Washburn’s ‘Tools and Human Evolution’, a discussion of the possible evolutionary role played by early tool-using Hominids. Washburn makes an important point that the behavioral changes brought about by successful tool-making cultures improved the selection toward greater intelligence. Other articles in this section are concerned with more traditional studies of man’s prehistory and the development of small permanent settlements and towns from earlier Neolithic sites. Adams presents a hypothesis in ‘The Origin of Cities’ that suggests that the aiversity of human experience provided by the urban environment, such as religious and craft activity, rather than available food surpluses accounts for the rapid growth and stability of ancient cities. In examining one particular city, Millon presents evidence that TeotihuacBn, Mexico’s largest pre-Columbian city, has structural features not unlike those of classical cities. Examples of design parallelism should interest the architect because they infer natural human preferences. The third section emphasizes both the traditional concerns of cultural anthropology and new areas of interest in contemporary societies. Rappaport’s ‘The Flow of Energy in an Agricultural Society’ examines the careful resource management of a New Guinean tribe and compares it with modern agricultural societies, which have simplified their energy sources to the point where they are subject to vast and potentially dangerous political and economic changes’ Cook‘s ‘The Flow of Energy in an Industrial Society’.
Individual predators differ in the level of risk they represent to prey. Because prey incur costs... more Individual predators differ in the level of risk they represent to prey. Because prey incur costs when responding to predators, prey can benefit by adjusting their antipredator behavior based on the level of perceived risk. Prey can potentially assess the level of risk by evaluating the posture of predators as an index of predators' motivational state. Like other prey species, humans might evaluate predator body posture as a prominent cue for assessing danger. We tested whether human participants adjusted their visual attention based on the postures of predators by presenting participants with photographic arrays of predators (lions) that varied in postures while we recorded the participants' gaze behavior. The participants searched for a standing lion (representing a high-risk target) among an array of reclining lions (representing low-risk distractors) or searched for a reclining lion among an array of standing lions. They also searched through similar arrays consisting of non-threatening prey (impalas) standing or reclining, rather than predators. Participants detected standing lions and impala faster than reclining lions and impala. Surprisingly, they detected standing lions at similar latencies as standing impala. They detected the reclining lions and impala more slowly because they spent more time looking at the standing lion and impala distractors and looked at more of those distractors. These results show that upright animals, regardless of whether they are predators or prey, attract attention in humans, and this could allow humans to rapidly evaluate predatory threats or the flight readiness of hunted game.
Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistor... more Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistoric cave and mobiliary art. Two experiments examined the saliency of snake scales and leopard rosettes to infants that are perceptually analogous to these patterns. Experiment 1 examined the investigative behavior of 23 infants at three daycare facilities. Four plastic jars (15 × 14.5 cm) with snake scales, leopard rosettes, geometric plaid, and plain patterns printed on yellowish-orange paper inside were placed individually on the floor on separate days during playtime. Fourteen 7-15-month-old infants approached each jar hesitantly and poked it before handling it for five times, the criterion selected for statistical analyses of poking frequency. The jars with snake scales and leopard rosettes yielded reliably higher poking frequencies than the geometric plaid and plain jars. The second experiment examined the gaze and grasping behavior of 15 infants (spanning 5 months of age) seated on the laps of their mothers in front of a table. For paired comparisons, the experimenter pushed two of four upright plastic cylinders (13.5 × 5.5 cm) with virtually the same colored patterns simultaneously toward each infant for 6 s. Video recordings indicated that infants gazed significantly longer at the cylinders with snake scales and leopard rosettes than the geometric plaid and plain cylinders prior to grasping them. Logistic regression of gaze duration predicting cylinder choice for grasping indicated that seven of 24 paired comparisons were not significant, all of which involved choices of cylinders with snake scales and leopard rosettes that diverted attention before reaching. Evidence that these biological patterns are salient to infants during an early period of brain development might characterize the integration of subcortical and neocortical visual processes known to be involved in snake recognition. In older individuals, memorable encounters with snakes and leopards coupled with the saliency of snake scales and leopard rosettes possibly biased artistic renditions of similar patterns during prehistoric times.
California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against thei... more California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against their two predators, the northern Pacific rattlesnake (Crotalus viridis oreganus) and Pacific gopher snake (Pituophis melanoleucus catenifer). Two studies were used to examine individual variation in antisnake behavior as it might be affected by selection operating on arousability, fearfulness, and aggressiveness. In Study 1 the behavioral consistency of two litters of lab-reared juveniles was examined at two age periods during encounters with a caged gopher snake and domestic cat. Close-range investigation and tail flagging appeared to be governed by short-term motivational states that were not strongly correlated across age. Age correlations revealed that individual tendencies to throw substrate were relatively consistent for the snake and even more so for the cat. In Study 2, wild-caught adults were obtained from five sites where rattlesnakes and gopher snakes were abundant and from five sites where these snakes were rare or absent. Squirrels in a seminatural laboratory setting were given balanced presentations of a caged rattlesnake and gopher snake separated by 5 days. Snakes were recognized by all squirrels as potentially dangerous, irrespective of experience, age, and selective regime. Substrate throwing also was positively correlated for the two snakes in both groups of adults, indicating that level of aggressiveness is a consistent component of temperament not specific to species of snakes. Physiological arousal was not correlated strongly for the two snakes, but it was significantly lower in squirrels from sites where snakes were abundant. This suggests some specialization to reduce anxiety that possibly enhances tactical decision making.
Wild and urban bonnet macaques (Macaca radiata) were studied in southern India to record alarm ca... more Wild and urban bonnet macaques (Macaca radiata) were studied in southern India to record alarm calls during presentations of realistic models of spotted and dark leopards (Panthera pardus) and an Indian python (Python molurus). Recordings of alarm calls were made from members of four forest troops at feeding stations who observed brief and prolonged presentations of fully exposed spotted and dark leopard morphs and partially concealed views of the spotted morph. Four different forest troops were presented a slowly moving python near feeding stations. Two predator-inexperienced urban troops from the city of Bangalore were presented either the spotted leopard morph briefly or the python. Analyses of alarm calls revealed differences in acoustic structure, such as a lower harmonic to noise ratio, which can be interpreted as reflecting the level of perceived threat rather than predator type. Noisy alarm calls likely indicate high states of physiological arousal that might provide eavesdropping troop members with information useful for assessing the urgency of the predatory threat. Lack of alarm-call distinctiveness characterizing predator type is complemented by explicit contextual information in which alarm calling to leopards never occurred on the ground whereas nearly all initial python-elicited alarm calls were made by individuals on the ground monitoring the python. The alarm calls of Bangalore monkeys distinguished the leopard and python models, with the latter engendering the noisiest calls and immediate flight to trees. Such flight is unnecessary with the python and suggests that, without appropriate experience with pythons, bonnet macaques adopt less predator specific refuge-seeking behavior.
Rock squirrels (Spermophilus variegatus) from two sites in south central New Mexico, where prairi... more Rock squirrels (Spermophilus variegatus) from two sites in south central New Mexico, where prairie (Crotalus viridis viridis) and western diamondback (Crotalus atrox) rattlesnakes are common predators, were assayed for inhibition of rattlesnake venom digestive and hemostatic activities. At statistically significant levels rock squirrel blood sera reduced the metalloprotease and hemolytic activity of venoms from C. v. viridis and C. atrox more than venom from an allopatric snake species, the northern Pacific rattlesnake (Crotalus oreganus). In contrast, general proteolytic activity of venom from C. oreganus was inhibited more by S. variegatus serum defenses than activity of venom from sympatric snakes. For all three venoms, incubation with squirrel sera increased the level of fibrinolysis over venom-only treatments. These results suggest that rock squirrels (S. variegatus) can defend against metalloproteases and other proteases after envenomation from at least two of five rattlesnake predators they might encounter. However, there were statistically significant differences between general proteolytic activity and fibrinolytic activity of C. v. viridis and C. atrox venom, suggesting that rock squirrels might be differentially vulnerable to these two predators. The hypothesis that prey resistance influences snake venom evolution in a predator-prey arms race is given further support by the previously cryptic variation in venoms detected when assayed against prey defenses.
Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among othe... more Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among others, in response to predators. The nature of this response is variable, with animals reacting more strongly in situations of increased vulnerability. Our research described here is the first formal study to investigate night-time antipredator behaviour in any species of elephants, Asian or African. We examined the provocative effects of elephant-triggered tiger and leopard growls while elephants attempted to crop-raid. Tigers opportunistically prey on elephant calves, whereas leopards pose no threat; therefore, we predicted that the elephant response would be reflective of this difference. Elephants reacted similarly cautiously to the simulated presence of felids of both species by eventually moving away, but differed markedly in their more immediate behavioural responses. Elephants retreated silently to tigergrowl playbacks, whereas they responded with aggressive vocalizations, such as trumpets and grunts, to leopard-growl playbacks. Elephants also lingered in the area and displayed alert or investigative behaviours in response to leopard growls when compared with tiger growls. We anticipate that the methods outlined here will promote further study of elephant antipredator behaviour in a naturalistic context, with applications for conservation efforts as well.
Wild bonnet macaques (Macaca radiata) have been shown to recognize models of leopards (Panthera p... more Wild bonnet macaques (Macaca radiata) have been shown to recognize models of leopards (Panthera pardus), based on their configuration and spotted yellow coat. This study examined whether bonnet macaques could recognize the spotted and dark melanic morph when partially concealed by vegetation. Seven troops were studied at two sites in southern India, the Mudumalai Wildlife Sanctuary and the Kalakad-Mundanthurai Tiger Reserve. The forequarters and hindquarters of the two leopard morphs were presented from behind thick vegetation to individuals at feeding stations 25 m away. Flight reaction times and frequency of flight were obtained from video for only those individuals who oriented towards the models prior to hearing alarm calls. Bonnet macaques exhibited faster reaction times and greater frequency of flight after looking at the spotted morph's forequarter than after looking at either its spotted hindquarter or the dark morph's forequarter. The hindquarter of the dark morph was ignored completely. Artificial neural network modeling examined the perceptual aspects of leopard face recognition and the role of spots as camouflage. When spots were integrated into the pattern recognition process via network training, these spots contributed to leopard face recognition. When networks were not trained with spots, spots did not act as camouflage by disrupting facial features.
Sleep results in a decrease in alertness, which increases an animal's vulnerability to predation.... more Sleep results in a decrease in alertness, which increases an animal's vulnerability to predation. Therefore, choice of sleeping sites would be predicted to incorporate predator-avoidance strategies. The current study, conducted in two national parks in southern India, examined the behaviors adopted by bonnet macaques (Macaca radiata) to reduce the risk of being preyed upon while sleeping. Bonnet macaques from an urban setting with a low predatory risk were included for comparison. The physical characteristics of the sleeping sites in the forest corresponded with features that were most difficult for predators to access; bonnet macaques selected emergent trees with high boles near human settlements. These trees typically overhung water. Within the canopy, individuals slept in huddled subgroups near the terminal ends of branches, preferentially selecting branches over water. Subgroups were generally composed of members of the same age and sex, which likely promoted social bonding. Adult males and females with infants selected branches higher than members of other age and sex categories. The lateral distances of individuals along branches from the main trunk were similar across demographic categories. The size of a subgroup appeared to be limited by the weight a branch could support; lateral distances were maintained by regulation of mean subgroup weight, with heavier individuals forming smaller subgroups. The urban troop slept on the top of a building. Subgroup compositions at the urban site were similar to those at the forest sites. However, subgroup size, not restricted by branch fragility, resulted in larger subgroups than those found in the forest. Our results indicate that bonnet macaques adopted a suite of behaviors that reduced their risk of being preyed upon at night by selecting sleeping sites that minimized predator encounters and by selecting the safest locations within the canopy.
We thank the Forest Department of Tamil Nadu for granting us permission to conduct research in th... more We thank the Forest Department of Tamil Nadu for granting us permission to conduct research in the Kalakad-Mundanthurai Tiger Reserve and the Mudumalai Wildlife Sanctuary and its staff for facilitating our research. We also thank Lynne Isbell and Donald H. Owings for their comments that improved this article. Finally, we thank our field assistants. Anil Kumar, M. Siddhan, and V. Yashoda, for their contributions in data collection and Chantal Stoner and Michele Tupin for their assistance in quantifying the videorecordings.
This study examined the perceptual features of leopards (Panthera pardus) used as recognition cue... more This study examined the perceptual features of leopards (Panthera pardus) used as recognition cues by bonnet macaques (Macaca radiata) at three sites in southern India. Two of these sites were protected deciduous forest areas, the Mudumalai Wildlife Sanctuary and the Kalakad-Mundanthurai Tiger Reserve. The third study site was a predator-rare urban setting, Bangalore city. Four models were presented for 10-s intervals: (1) upright spotted leopard in a stalking pro le with its head facing the subjects; (2) the same spotted model presented upside down; (3) a dark-brown leopard model with the same con guration as the spotted model; and nally (4), the dark-brown model presented upside down. The upright models characterized the two leopard morphs found in the wild-spotted and dark melanic. Inverted presentations of the spotted model examined the effects of the same con guration in an incongruous position to document whether leopard spots were still recognized. Differences between models were examined using alarm calls and ight elicitation as indices of fear. The spotted upright model was found to be the most feared, followed by the spotted upside-down model, the dark upright model, and nally the dark upside-down model. Analysis of when individuals looked at troop members to assess risks revealed that the spotted upright and dark upsidedown models engendered signi cantly lower frequencies of information seeking; the upright model typically engendered immediate ight and the dark upside-down model was generally ignored. The spotted upside-down model and the dark upright model engendered high rates
Young animals are known to direct alarm calls at a wider range of species than adults. Our field ... more Young animals are known to direct alarm calls at a wider range of species than adults. Our field study examined age-related differences in the snake-directed antipredator behavior of infant, juvenile, and adult white-faced capuchin monkeys (Cebus capucinus) in terms of alarm calling, looking behavior, and aggressive behavior. In the first experiment, we exposed infant and juvenile white-faced capuchins to realistic-looking inflatable models of their two snake predators, the boa constrictior (Boa constrictor) and neotropical rattlesnake (Crotalus durissus) and a white airplane as a novel control. In the second experiment, infants, juveniles, and adults were presented photographic models of a coiled boa constrictor, rattlesnake, indigo snake (Drymarchon corais), a noncapuchin predator, and a white snake-like model. We found that antipredator behavior changed during the immature stage. Infants as young as 4 months old were able to recognize snakes and display antipredator behavior, but engaged in less snake-model discrimination than juveniles. All age classes exhibited a lower response to the white snake-like model, indicating that the absence of color and snake-scale patterns affected snake recognition. Infants also showed a higher level of vigilance after snake-model detection as exhibited by a higher proportion of time spent looking and head cocking at the models. Aggressive antipredator behavior was found in all age classes, but was more prevalent in juveniles and adults than infants. This study adds to the knowledge of development of antipredator behavior in primates by showing that, although alarm calling behavior and predator recognition appear at a very young age in capuchins, snake-species discrimination does not become apparent until the juvenile stage. Am. J.
Wild bonnet macaques (Macaca radiata) were studied in southern India to assess their ability to d... more Wild bonnet macaques (Macaca radiata) were studied in southern India to assess their ability to discriminate non-venomous, venomous and predatory snakes. Realistic snake models were presented to eight troops of bonnet macaques at feeding stations and their behavior was video-recorded 3 min before and 3 min after snake exposure. Snakes presented were: (1) venomous Indian cobra (Naja naja) displaying an open hood with ÔeyespotsÕ; (2) venomous common Indian krait (Bungarus caeruleus); (3) non-venomous green keelback (Macropisthodan plumbicolor); (4) non-venomous rat snake (Ptyas mucosus); and (5) Indian python (Python molurus) which preys on macaques. Latencies to detect and react to the snakes were evaluated to determine initial responsiveness. Longer-term assessment was measured as the percentage of time individuals looked at the snakes and monitored the activity of nearby individuals before and after snake detection. All snake models engendered caution and maintenance of a safe distance. Alarm calling occurred only during python presentations. The cobra engendered a startle response or running in the largest percentage of individuals after its detection, whereas the rat snake and python elicited bipedal standing or ambulating to monitor the snakes. We also examined the influence of age on snake recognition. Juveniles and subadults looked at the cobra, krait, and python for a larger percentage of time than adults did; albeit, adults looked at the python substantially longer than at the other snakes. Age differences in behavior suggest that, with the exception of the python, repeated experience with snakes in the wild moderates excitability, consistent with the likely threat of envenomation.
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