Antipredator Behavior Research Articles

Olfactory predator recognition in the brown mouse lemur (Microcebus rufus) in Ranomafana National Park, Madagascar.

Predator odors such as urine and feces are known to elicit antipredator behaviors in prey including avoidance, fear, and curiosity. We measured how wild brown mouse lemurs (Microcebus rufus) responded to odors of mammalian, avian, and snake predators as well as nonpredator controls. The first experiment took place under controlled conditions in a laboratory where we recorded the occurrence of four behavioral categories (ignore, curiosity, alert, and fear) in response to a single odor. Subjects exhibited behavioral change significantly more often in response to the predator than to control stimuli, but did not distinguish between familiar and unfamiliar predators. Mammalian predator urine and feces were most likely to elicit behavioral change. The owl was the only predator to never elicit behavioral change, possibly because owls do not provide relevant odor cues. A second experiment employing live traps in the forest found that neither predator nor control odors affected the likelihood of capture. Due to their longevity, odors do not provide accurate information of spatial and temporal risk, and while mouse lemurs may have initially hesitated to enter a trap, in the absence of additional information about risk, they may have eventually ignored the stimuli. This study found that brown mouse lemurs are able to distinguish between predator and nonpredator odors, and that risk assessment may be affected by the experience, as well as predator and sensory stimulus quality.

Does Liolaemus lemniscatus eavesdrop on the distress calls of the sympatric weeping lizard?

For a prey, its best ticket to stay alive is to get early and accurate information on predation risk and so, escape from predation at low cost. Some prey species have evolved the ability to eavesdrop signals intended for others, which contain information on predation risk. This is the case for the vocalizations produced by prey species when interacting with predators. Although primarily studied in birds and mammals, eavesdropping on vocal signals has been recorded in some lizard species. Here, we explored whether the lizard Liolaemus lemniscatus eavesdrops on the distress calls of its sympatric species, the Weeping lizard (L. chiliensis). Individuals of the Weeping lizard respond to these calls by displaying antipredator behaviours (i.e., reduced movement), and individuals of L. lemniscatus may potentially display similar defences if they decode the information contained in these calls. Our playback experiments showed that individuals of L. lemniscatus responded to the sound stimuli (distress calls and white noise), reducing their activity, but they did not discriminate between these two stimuli, suggesting that L. lemniscatus does not eavesdrop on the distress calls of its sympatric lizard species. We discuss some hypotheses to explain the lack of eavesdropping by L. lemniscatus on the Weeping lizard distress calls.

White-handed gibbons discriminate context-specific song compositions

White-handed gibbons produce loud and acoustically complex songs when interacting with their neighbours or when encountering predators. In both contexts, songs are assembled from a small number of units although their composition differs in context-specific ways. Here, we investigated whether wild gibbons could infer the ‘meaning’ when hearing exemplars recorded in both contexts (i.e. ‘duet songs’ vs. ‘predator songs’). We carried out a playback experiment by which we simulated the presence of a neighbouring group producing either its duet or a predator song in order to compare subjects’ vocal and locomotor responses. When hearing a recording of a duet song, subjects reliably responded with their own duet song, which sometimes elicited further duet songs in adjacent groups. When hearing a recording of a predator song, however, subjects typically remained silent, apart from one of six groups which replied with its own predator song. Moreover, in two of six trials, playbacks of predator songs elicited predator song replies in non-adjacent groups. Finally, all groups showed strong anti-predator behaviour to predator songs but never to duet songs. We concluded that white-handed gibbons discriminated between the two song types and were able to infer meaning from them. We discuss the implications of these findings in light of the current debate on the evolutionary origins of syntax.

Do prairie voles (Microtus ochrogaster) change their activity and space use in response to domestic cat (Felis catus) excreta?

Abstract Behavioral changes that reduce the risk of predation in response to predator-derived odor cues are widespread among mammalian taxa and have received a great deal of attention. Although voles of the genus Microtus are staples in the diet of many mammalian predators, including domestic cats (Felis catus), there are no previous studies on vole space utilization and activity levels in response to odor cues from domestic cats. Therefore, the objective of our study was to investigate responses of adult prairie voles (Microtus ochrogaster) living in semi-natural habitats to odor cues from domestic cat excreta. Contrary to expectations, neither adult males or females showed significant changes in space use or willingness to enter traps in response to cat odors. One hypothesis to explain our results are that prairie voles have not co-evolved with domestic cats long enough to respond to their odors. Other possible explanations include whether levels of odors in the environment were sufficient to trigger a response or that the perceived risk of predation from odor cues alone did not outweigh relative costs of changing space use and activity levels. Future studies should consider multiple factors when determining what cues are sufficient to elicit antipredatory behavior.

Fight or flight: Geographic variation in antipredator defenses by cinereous tits

In the face of death from predation, parent birds have to choose between prioritizing current versus future reproduction. Previous studies have shown that when exposed to predation risk, birds breeding in the tropics prioritize their own safety, whereas birds breeding at high latitudes prioritize the safety of future generations. However, this phenomenon has rarely been investigated among populations within a single bird species. Here, we studied the anti-predation behavior of female birds in response to a human observer of four cinereous tit (Parus cinereus) populations during their incubation period across different latitudes in China. When confronted with nest predation risk induced by the presence of a human, the probability of escape by cinereous tits decreased with increasing latitude, that is, the proportion of female birds that escaped from the nest was significantly larger in southern than in northern populations. For female birds that did not leave the nest, the proportion of individuals who produced a hissing call for nest defense was significantly lower in the southern than in the northern populations. In addition, nest defense behaviours were unrelated to nest predation rates, and clutch size in the southern cinereous tit populations was significantly smaller than that in the northern population, it was, therefore, likely that nest defense behaviours were related to clutch size. The present study confirms within a single species that under predation risk, female birds in the tropics prioritize future over current reproduction, while the birds breeding at high latitudes do the opposite.

Vessel noise affects routine swimming and escape response of a coral reef fish.

An increasing number of studies have shown that anthropogenic noise can negatively affect aspects of the anti-predator behaviour of reef fishes, potentially affecting fitness and survival. However, it has been suggested that effects could differ among noise sources. The present study compared two common sources of anthropogenic noise and investigated its effects on behavioural traits critical for fish survival. In a tank-based experiment we examined the effects of noise from 4-stroke motorboats and ships (bulk carriers > 50,000 tonnes) on the routine swimming and escape response of a coral reef fish, the whitetail damselfish (Pomacentrus chrysurus). Both 4-stroke boat and ship noise playbacks affected the fast-start response and routine swimming of whitetail damselfish, however the magnitude of the effects differed. Fish exposed to ship noise moved shorter distances and responded more slowly (higher response latency) to the startle stimulus compared to individuals under the 4-stroke noise treatment. Our study suggests that 4-stroke and ship noise can affect activity and escape response of individuals to a simulated predation threat, potentially compromising their anti-predator behaviour.

Prey vulnerability and predation pressure shape predator-induced changes in O2 consumption and antipredator behaviour

Predators regulate prey abundance (direct predation) as well as influencing their metabolism and behaviour (indirect effects) through the perception of risk. Antipredator traits are informed by individual experience of risk, which may vary over environmental gradients and through ontogeny. As prey grow, individual vulnerability generally diminishes, and the reduction in individual vulnerability with ontogenetic growth can potentially lead to size refugia, ultimately nullifying the impacts of direct predation. Despite the ecological importance of the indirect effects of predation and the disproportionate influence larger individuals have on ecological level processes, there has been little focus on the potential indirect effects of predation risk on invulnerable prey. Using a combination of field and laboratory experiments, we measured the changes in routine oxygen consumption of vulnerable and invulnerable size classes of the intertidal snail Nucella lapillus (dogwhelk), exposed to effluent from its crab predator Carcinus maenas. To test the potential influence of prior experience of predation risk, measurements were conducted on populations naturally exposed to different levels of predation pressure. Field results showed that only invulnerable snails modified their routine oxygen consumption in the presence of risk, and this occurred across all populations. Oxygen consumption rates in the laboratory, however, contradicted the pattern, with only vulnerable prey responding to the perception of risk. Metabolic responses of both vulnerable and invulnerable prey under field and laboratory conditions are discussed in the context of asset protection and prey energetic state. Observations of snail behaviour in the laboratory showed that dogwhelks from exposed shores, where predatory risk is higher, were more likely to exhibit antipredator behaviour. Importantly, our findings provide evidence that the indirect effects of predators remain influential even after prey are no longer susceptible to direct predation and add to the growing body of evidence highlighting the ecological importance of indirect predation.

Female cuckoo calls elicit vigilance and escape responses from wild free-range chickens

Mimicry is widespread in the animal kingdom. Parasitic cuckoos can reduce the risk of their offspring being rejected by employing morphological and egg mimicry. Female common cuckoos (Cuculus canorus) can deceive their hosts by mimicking sparrowhawk (Accipiter nisus) calls, thus improving brood parasitism success. However, few experiments have confirmed the hypothesis that female cuckoos can successfully mimic sparrowhawk calls. We used two populations of wild free-range chickens (Gallus gallus domesticus), which are not cuckoo hosts, to study the effects of four different types of bird calls on their anti-predatory behavior. Results showed that both female cuckoo and sparrowhawk calls elicited vigilance and escape responses from chickens, while the chickens did not respond to either male common cuckoo or Oriental turtle dove (Streptopelia orientalis) calls. This suggests that female cuckoo calls can not only deceive their hosts, but also successfully deceive their non-host birds. Our study further confirms the accuracy with which female cuckoos can mimic sparrowhawk calls.

Maternal predation risk increases offspring’s exploration but does not affect schooling behavior

Abstract The environment that parents experience can influence their reproductive output and their offspring’s fitness via parental effects. Perceived predation risk can affect both parent and offspring phenotype, but it remains unclear to what extent offspring behavioral traits are affected when the mother is exposed to predation risk. This is particularly unclear in live-bearing species where maternal effects could occur during embryogenesis. Here, using a half-sib design to control for paternal effects, we experimentally exposed females of a live-bearing fish, the guppy (Poecilia reticulata), to visual predator cues and conspecific alarm cues during their gestation. Females exposed to predation risk cues increased their antipredator behaviors throughout the entire treatment. Offspring of mothers exposed to the predation stimuli exhibited more pronounced exploratory behavior, but did not show any significant differences in their schooling behavior, compared to controls. Thus, while maternally perceived risk affected offspring’s exploration during early stages of life, offspring’s schooling behavior could be influenced more by direct environmental experience rather than via maternal cues. Our results suggest a rather limited role in predator-induced maternal effects on the behavior of juvenile guppies.

Risk assessment in the plateau pika (Ochotona curzoniae): intensity of behavioral response differs with predator species

BackgroundThe ability of a prey species to assess the risk that a predator poses can have important fitness advantages for the prey species. To better understand predator–prey interactions, more species need to be observed to determine how prey behavioral responses differ in intensity when approached by different types of predators. The plateau pika (Ochotona curzoniae) is preyed upon by all predators occurring in its distribution area. Therefore, it is an ideal species to study anti-predator behavior. In this study, we investigated the intensity of anti-predator behavior of pikas in response to visual cues by using four predator species models in Maqu County on the eastern Qinghai-Tibetan Plateau.ResultsThe behavioral response metrics, such as Flight Initiation Distance (FID), the hiding time and the percentage of vigilance were significantly different when exposed to a Tibetan fox, a wolf, a Saker falcon and a large-billed crow, respectively. Pikas showed a stronger response to Saker falcons compared to any of the other predators.ConclusionsOur results showed that pikas alter their behavioral (such as FID, the hiding time and the vigilance) response intensity to optimally balance the benefits when exposed to different taxidermy predator species models. We conclude that pikas are able to assess their actual risk of predation and show a threat-sensitive behavioral response.

Survival rates on pre-weaning European hares (Lepus europaeus) in an intensively used agricultural area

The primary cause of the long-term decline in European hares’ (Lepus europaeus) population throughout Europe is widely assumed to be the intensification of agriculture. A critical component in this population dynamics is seen in the survival of leverets from birth to reproductive age. In European hares, the first stage of life until weaning has been sparsely studied, in particular habitat selection, movements and survival rate, as juveniles’ precocial lifestyle is dominated by any kind of anti-predation behaviour. In the present study, free-living and pre-weaning European hares were detected systematically by thermography (n = 394), being radio-tagged or marked (n = 229) from birth until the fifth week of life to research the early juvenile survival and proximate causes of mortality. Kaplan-Meier survival curves were computed overall and in relation to the strata of season, sex and type of daytime resting place. The survival rate of radio-tagged leverets was 0.35 in the first month of life, and 0.63, 0.52 and 0.44 for the first, second and third week of life, respectively. Approximately 21.6% and 50% of all confirmed deaths occurred during the first 7 and 13 days after birth. By the end of the 4th week of life, the mortality rate caused by predation, suspected predation, agricultural practices and unexplained cases was 41.7%, 36.7%, 11.7% and 10.0%, respectively. There was no significant difference in survival between the sexes and seasons. In contrast, young hares died more frequently as a consequence of choosing a hiding place without shelter during the daytime.

Differences in cautiousness between mainland and island Podarcis siculus populations are paralleled by differences in brain noradrenaline/adrenaline concentrations

Adaptive behavior is shaped by the type and intensity of selection pressures coming from the environment, such as predation risk and resource availability, and can be modulated by individual's neuroendocrine profile involving steroid hormones and the brain-stem monoaminergic circuits projecting to forebrain structures. Boldness when faced with a predator and exploration/activity when confronted with a new environment reflect the degree of cautiousness and/or “risk-taking” of an individual. In this study we have explored to which extent two populations of Podarcis siculus occupying different ecological niches: mainland (ML) and an islet (ISL) differ in the level of cautiousness and whether these differences are paralleled by differences in their monoaminergic profiles. Boldness was tested in the field as antipredator behavior, while novel space and object explorations were tested in a laboratory setting in an open field apparatus. Finally, serotonin, dopamine, noradrenaline (NA) and adrenaline (ADR) concentrations were measured in whole brain samples by ELISA. Lizards from ML population spent significantly more time hiding after a predator encounter in the field, displayed lower intensity of novel space exploration in a laboratory setting, and contained significantly higher whole-brain concentrations of NA and ADR than their ISL counterparts. Parallelism between the level of risk-taking behavior and concentrations of neurotransmitters mediating alertness and reaction to stress suggests that the differing environmental factors on ML and ISL may have shaped the degree of cautiousness in the residing lizard populations by affecting the activity of NA/ADR neural circuits.

Waterborne agrichemicals compromise the anti-predatory behavior of zebrafish.

Due to human activities, there is an increasing presence of agrochemicals residues in water bodies, which could be attributed to an increased use of these chemicals, incorrect disposal of packaging materials, and crop leaching. The effects of these residues on prey-predator relationship of aquatic animals are poorly known. Here, we show that fish acutely exposed to glyphosate, 2,4-D, and methylbenzoate-based agrichemicals have their anti-predatory responses impaired. We exposed zebrafish to sub-lethal concentrations of agrichemicals and evaluated their behavioral reaction against a simulated bird predatory strike. We observed that agrichemical-exposed fish spent more time in a risky area, suggesting that the pesticides interfered with their ability of risk perception. Our results highlight the impairment and environmental consequences of agrochemical residues, which can affect aquatic life and crucial elements for life (food web) such as the prey-predator relationship.

Short exposure to cadmium disrupts the olfactory system of zebrafish (Danio rerio) – Relating altered gene expression in the olfactory organ to behavioral deficits

Fish strongly rely on olfaction as a variety of essential behaviors such as foraging and predator avoidance are mediated by the olfactory system. Cadmium (Cd) is known to impair olfaction and accumulate in the olfactory epithelium (OE) and bulb (OB) of fishes. In the present study, the acute toxicity of Cd on olfaction in zebrafish (Danio rerio) was characterized on the molecular and behavioral level. To this end, quantitative real-time PCR was performed in order to analyze the expression of selected genes in both the OE and OB. Moreover, the response of zebrafish to an alarm cue was investigated. Following 24 h of exposure to Cd, the expression of genes associated with olfactory sensory neurons was reduced in the OE. Furthermore, the antioxidant genes peroxiredoxin 1 (prdx1) and heme oxygenase 1 (hmox1), as well as the metallothionein 2 gene (mt2) were upregulated in the OE, whereas hmox1 and the stress-inducible heat shock protein 70 gene (hsp70) were upregulated in the OB upon exposure to Cd. Following stimulation with a conspecific skin extract, zebrafish displayed a considerable disruption of the antipredator behavior with increasing Cd concentration. Taken together, Cd impaired olfaction in zebrafish, thereby disrupting the antipredator response, which is crucial for the survival of individuals. Cellular stress followed by disruption of olfactory sensory neurons may have contributed to the observed behavioral deficits.

Complex distress calls sound frightening: the case of the weeping lizard

Individuals of many species utter distress calls when are attacked or trapped by a predator. These vocalizations can help them to escape but may also help conspecifics to reduce their predation risk, by inducing antipredator behaviours. Calls can encode information that modulates these antipredator responses, and the ‘nonlinearity and fear hypothesis’ proposes that complex nonlinear calls may trigger more fearful responses, because they encode higher levels of stress. We tested this hypothesis with the weeping lizard, Liolaemus chiliensis, which utters distress calls with and without nonlinear phenomena (complex and simple calls, respectively), and conspecifics respond to simple calls with antipredator behaviours. Here, we evaluated whether this species discriminates between these two types of calls, predicting higher levels of fear with complex calls. We also tested whether lizards experience less fear if calls are perceived in a safe environment, such as one full of their own scents (‘home’). Our playback experiments showed that complex calls scared the lizards more than simple calls, triggering a reduction in activity, and prolonging attempts to escape. Lizards in their own-scented environments took longer to restore their activity after hearing complex than simple calls, suggesting that this combination of stimuli was more alarming. We postulate that the predation event was unexpected at ‘home’, which together with the nonlinearity of the call made a more frightening event for the lizards.

Training fails to elicit behavioral change in a marsupial suffering evolutionary loss of antipredator behaviors

Abstract Attempts to reintroduce threatened species from ex situ populations (zoos or predator-free sanctuaries) regularly fail because of predation. When removed from their natural predators, animals may lose their ability to recognize predators and thus fail to adopt appropriate antipredator behaviors. Recently, northern quolls (Dasyurus hallucatus; Dasyuromorpha: Dasyuridae) conserved on a predator-free “island ark” for 13 generations were found to have no recognition of dingoes, a natural predator with which they had coevolved on mainland Australia for about 8,000 years. A subsequent reintroduction attempt using quolls acquired from this island ark failed due to predation by dingoes. In this study, we tested whether instrumental conditioning could be used to improve predator recognition in captive quolls sourced from a predator-free “island ark.” We used a previously successful scent-recognition assay (a giving-up density experiment) to compare predator-scent recognition of captive-born island animals before and after antipredator training. Our training was delivered by pairing live predators (dingo and domestic dog) with an electrified cage floor in repeat trials such that, when the predators were present, foraging animals would receive a shock. Our training methodology did not result in any discernible change in the ability of quolls to recognize and avoid dingo scent after training. We conclude either that our particular training method was ineffective (though ethically permissible); or that because these quolls appear unable to recognize natural predators, predator recognition may be extremely difficult to impart in a captive setting given ethical constraints. Our results point to the difficulty of reinstating lost behaviors, and to the value of maintaining antipredator behaviors in conservation populations before they are lost.

Male care status influences the risk-taking decisions in a glassfrog

Parental care increases offspring survival, but may impose costs by decreasing adult survival or mating opportunities. Because individuals have limited resources, time allocation and risk decisions are expected to vary according to the care status and threat faced by parents. Herein, we evaluated the sources of mortality of clutches of the glassfrog Hyalinobatrachium cappellei and the importance of paternal care for offspring survival. We also compared time allocation patterns and antipredator behavior between attending and non-attending males. Using naturalistic observations and field experiments with different dummy predators, we hypothesized that (1) offspring survival would be positively correlated with paternal care; (2) attending males would spend most of the time caring for the embryos, while non-attending males would spend more time foraging and calling; (3) attending males would prioritize their own survival when facing a high risk of predation, even with negative impacts on offspring survival. Main sources of embryo mortality included predation and dehydration, and offspring survivorship was almost totally dependent on paternal care. Although non-attending males spent more time calling and foraging, attending males also called and were able to attract females and increase their mating success. However, contrary to our prediction, we found that attending males were more risk-tolerant, increasing not only offspring survival but also their mortality risk. Our findings highlight the importance of the predation risk level on parents’ decisions and that the reproductive status may play a significant role in determining antipredator behavior and mating success in glassfrog males. In species with parental care, parents face a trade-off between investment in current offspring survival and chances of future reproduction. Hence, it is expected that natural selection will favor parents that attend offspring without incurring in higher risk of predation. We investigated time allocation patterns and behavioral responses to different levels of threat in a glassfrog with paternal care. Using field observations and predation experiments, we found that attending and non-attending males of Hyalinobatrachium cappellei behaved differently depending on their care status and level of threat. Males were more likely to tolerate high risks only when they were caring for clutches. We also found that the commitment of males to continue caring resulted in higher offspring survival. Parental care behavior increased not only larvae hatching success, but also matting success of attending males, suggesting that paternal care might be under sexual selection.

Mimicry in Cretaceous Bugs.

SummaryMimicry is ubiquitous in nature, yet understanding its origin and evolution is complicated by the scarcity of exceptional fossils that enable behavioral inferences about extinct animals. Here we report bizarre true bugs (Hemiptera) that closely resemble beetles (Coleoptera) from mid-Cretaceous amber. The unusual fossil bugs are described as Bersta vampirica gen. et sp. nov. and Bersta coleopteromorpha gen. et sp. nov. and are placed into a new family, Berstidae fam. nov. The specialized mouthparts of berstids indicate that they were predaceous on small arthropods. Their striking beetle-like appearance implies that they were either involved in defensive mimicry or mimicked beetles to attack unsuspecting prey. The latter would represent the first case of aggressive mimicry in the invertebrate fossil record. These findings enrich our understanding of the paleoecological associations and extinct behavioral strategies of Mesozoic insects.

Conservation implications of using an imitation carnivore to assess rarely used refuges as critical habitat features in an alpine ungulate.

Understanding relationships between animals and their habitat is a central goal in ecology with important implications for conservation. Misidentified habitat requirements can have serious repercussions because land protection or reintroductions might occur in less than optimal habitat. Studies of resource selection have greatly facilitated an understanding of ecological relationships but can be improved when vital yet infrequently utilized habitat features are more fully described. A critical element for many prey species is escape terrain or some other form of refuge to avoid predation. Mountain goats (Oreamnos americanus) are well known for their use of cliffs to avoid predation, but a survey of the literature revealed at least twelve different approximations of goat escape terrain, ranging from > 25° to > 50° slopes. Here, we seek to (1) enhance estimates of mountain goat escape terrain and antipredator behavior, and (2) highlight the limitations of the assumption that the time an animal spends in an area is proportional to importance. To improve estimates of goat escape terrain, we conducted field work across two years (2014–15) in Glacier National Park, Montana USA and manipulated apparent predation risk by exposing mountain goats to a threatening simulated grizzly bear (Ursus arctos) treatment and a non-threatening ungulate (control) treatment. Mountain goats moved in response to the simulated bear but not in response to the simulated ungulate, with shorter latencies to move for subjects in larger groups and at shorter distances to the simulated threat. Through a used-unused resource selection function we tested 22 landscape variables to describe the use of escape terrain. Proximity to slopes greater than 60° best explained the locations to which mountain goats fled after exposure to the simulated bear, and the average slope of these escape locations was 56.5° (±14.1 S.D.). Our results suggest that mountain goat escape terrain be considered at slopes of 60° as a minimum because our simulated threat did not include pursuit of goats and, thus, slopes of 60° are likely underestimates of actual escape terrain. Additionally, because direct interactions between carnivores and goats seldom occur, serious escape terrain is infrequently used. Past estimates of escape may have miscalculated the slopes which goats select for in response to predation risk. Based on experimental approaches in the wild, we suggest that anti-predator behavior should be included in studies of resource selection when the goal is to consider habitat as a predictor for conservation success. Finally, we discuss evidence suggesting a past mountain goat introduction failed due to lack of adequate escape terrain and subsequent recolonization of a predator.

Red-tailed monkeys (Cercopithecus ascanius) prey upon and mob birds in the Issa Valley, western Tanzania.

Interactions between monkeys and birds are rarely observed and, consequently, rarely described in the scientific literature. We recorded two encounters between birds (Prionops plumatus and Strix woodfordii) and red-tailed monkeys (Cercopithecus ascanius) in a woodland-mosaic habitat in western Tanzania. We observed a male red-tailed monkey consume a small bird in its entirety. Although only a few feathers remained, we provisionally identified the bird as a white-crested helmetshrike. We also observed a group of red-tailed monkeys mobbing, but not killing, an African wood owl on the forest floor. This is the first reported observation of this kind. These encounters suggest that guenons may generalize large-bodied avians as threats and small-bodied avians as potential prey. Hetero-specific encounters such as these provide insights into primate diet and anti-predatory behavior.