Snake Predators Research Articles

Aposematic colouration does not explain fear of snakes in humans

Snakes elicit a higher level of fear than other vertebrate animals, yet specific cues responsible for fear of snakes are equivocal. The bright colouration hypothesis suggests that fear responses to snakes are triggered by aposematic colouration, not by snakes per se. We investigated the role of aposematic colouration in fear of snakes in a sample of 10- to 15-year-old Slovak children. Both aposematically and cryptically coloured snakes presented as both colour and black-and-white pictures received higher perceived fear scores than other vertebrates. This suggests that aposematic colouration does not play a crucial role in eliciting fear of snakes. Our results support the snake detection theory suggesting that the human visual system has been influenced by long coexistence between predatory snakes and mammals. As a result, humans have evolved an attentional bias ultimately focused on the correct and rapid detection of these threats.

Selective advantage conferred by resemblance of aposematic mimics to venomous model

Abstract Mimicry is an excellent example of how natural selection can act on color, morphology, and behavior of species. Herein we assess predation rates on coral snake mimics in Central Brazil, a region with many mimics but only a single model, to answer the following questions: (i) Do predators avoid attacking coral snake mimics? (ii) Does the degree to which mimics resemble their venomous model affect the frequency of predator attacks? (iii) Do predators attack different body regions in mimics with different color patterns? Our experiment was conducted in the Chapada dos Veadeiros National Park, in the municipality of Alto Paraíso de Goiás, state of Goiás, Brazil. To evaluate predation rates on the different mimic patterns, we made 2,400 clay snake replicas using pre-colored nontoxic plasticine and distributed them in open savanna landscapes within the park. A total of 164 (6.83%) replicas were attacked by predators of snakes. Among these attacks, 121 were attacks by birds, and 43 were attacks by carnivorous mammals. Logistic regression and Fisher’s exact test indicated that replicas with red, white, and black coloration are less likely to be attacked than were grey replicas, and coral snake replicas were attacked more often at the “head” end. Also, the greater the similarity to the pattern of venomous coral snakes, the rarer the attack on the replica. Our study underscores the strong selective force that protects coral snake mimics from predators. Our findings reinforce resemblance to the model as an extremely effective strategy in a complex natural system with only one model and numerous mimics.

Predation risk and breeding site value determine male behavior and indirectly affect survivorship of their offspring

Predation is one of the main drivers of behavioral adaptation in prey. In species with parental care, predation can affect survival of both adults and the offspring under their care. This effect can be further modulated by or combined with other factors that contribute to mating and reproductive success of adults, such as the quality of their breeding site. Using the nest guarding behavior of a treefrog with paternal egg attendance, Kurixalus eiffingeri, we quantify the effects of predation on the behavior of adult frogs and the survival of their offspring. We observed predator avoidance behavior of male frogs guarding empty breeding sites or breeding sites with eggs in response to the introduction of a predatory snake, Dinodon rufozonatum. We hypothesized that male nest guarding behavior would be negatively correlated with predation risk and positively correlated with their clutch sizes. Furthermore, we predicted that predator avoidance in male frog would negatively impact the survivorship of their offspring. We found that breeding site fidelity in male frogs was determined by perceived predation risk and breeding site value, with more males abandoning sites when exposed to high mortality risks (presence of a snake) and when the reproductive benefits (number of offspring) were low. In addition, we found that the willingness of males to return to their breeding sites was positively correlated with their clutch sizes. Abandoning breeding sites, however, can be costly to males, because abandoned eggs had a lower hatching rate. Our findings provide empirical evidence of how the costs and benefits of predation risk and breeding site value can determine the behavior of an amphibian with parental care. When faced with predation risks, the willingness of individuals to maintain their ownership over nest sites can have significant effects on their reproductive success. For species with parental care, nest defense can also be critical for offspring survival. Using an East Asian treefrog with male egg attendance, we hypothesized that males would maximize their reproductive output by increasing investment for nest sites with low predation risks and with more offspring. We found that males are more likely to invest in nest attendance when risks are low and benefits of offspring survival are high. Moreover, we found that the willingness of males to continue parental investment resulted in an increase in survivorship of their offspring. Our results show that perceived risks and benefits to the adults are important factors in determining offspring survival in an amphibian species with parental care.

Safety first: terrestrial predators drive selection of highly specific nesting sites in colonial‐breeding birds

Nesting is a critical yet hazardous life stage for many birds. For colonial‐breeding birds, the conspicuousness of the colony to predators suggests immense pressure to select optimal colonial nesting sites. But what drives selection of those sites? As with solitary nesting birds, reducing access by predators may be the single most important factor. If so, knowledge of the predators involved and the attributes of different potential colony sites can allow us to predict the features that make a site especially safe. We examined the attributes of trees used by breeding colonies of metallic starlings Aplonis metallica in tropical Australia, and experimentally tested if those attributes prevented nest access by predatory snakes. Our surveys confirmed that tree choice by starling nesting colonies is highly non‐random, with all colonies located in tall trees in rainforest clearings, with no low branches and smooth bark. Experimental tests demonstrated that the climbing ability of predatory snakes depends upon bark rugosity, and that colony access by snakes depends on tree attributes such as bark rugosity and canopy connectivity. Our study confirms that colonial‐nesting starlings select colony sites that provide a safe refuge from predation. Intense predation pressure may have driven the evolution of stringent breeding habitat criteria in many other species of colonial‐breeding birds.

Mobbing behavior and fatal attacks on snakes by Fasciated Antshrikes (Cymbilaimus lineatus)

Birds often mob potential predators, which alerts other prey individuals of the danger and drives the predator away. Participation in, or increased intensity of mobbing is often associated with breeding activity suggesting an important function in the defense of nests and young. Less is known about bird mobbing of snakes, however, although these are important predators of birds, particularly at nests in tropical forests. Here, we report observations of mobbing behavior, some escalating into fatal attacks, of snakes by individuals of a tropical bird species, the Fasciated Antshrike (Cymbilaimus lineatus). In addition, we conducted snake-model presentations when Fasciated Antshrike pairs had active nests, and when not nesting, to examine the extent that pairs maintain a mobbing response outside of the nesting period. Pairs approached the snake model on average within 59 s (range 15–120 s) and 0.9 m (0.1–5 m) with no difference with nesting status. Our observations of mobbing behavior and fatal attacks suggest that passerines can also present a threat to potential snake predators and that mobbing is likely important in influencing predation rate. Mobbing when not nesting may be important in predator deterrence in bird species with year-round residency, and could influence territory quality and reproductive success. Forest birds that hunt large insects or other potentially dangerous prey may have morphological and cognitive specializations that help them to effectively mount a successful attack against predatory snakes.

Effects of pregnancy on body temperature and locomotor performance of velvet geckos

Pregnancy is a challenging period for egg laying squamates. Carrying eggs can encumber females and decrease their locomotor performance, potentially increasing their risk of predation. Pregnant females can potentially reduce this handicap by selecting higher temperatures to increase their sprint speed and ability to escape from predators, or to speed up embryonic development and reduce the period during which they are burdened with eggs (‘selfish mother’ hypothesis). Alternatively, females might select more stable body temperatures during pregnancy to enhance offspring fitness (‘maternal manipulation hypothesis’), even if the maintenance of such temperatures compromises a female's locomotor performance. We investigated whether pregnancy affects the preferred body temperatures and locomotor performance of female velvet geckos Amalosia lesueurii. We measured running speed of females during late pregnancy, and one week after they laid eggs at four temperatures (20°, 25°, 30° and 35°C). Preferred body temperatures of females were measured in a cost-free thermal gradient during late pregnancy and one week after egg-laying. Females selected higher and more stable set-point temperatures when they were pregnant (mean =29.0°C, Tset =27.8–30.5°C) than when they were non-pregnant (mean =26.2°C, Tset =23.7–28.7°C). Pregnancy was also associated with impaired performance; females sprinted more slowly at all four test temperatures when burdened with eggs. Although females selected higher body temperatures during late pregnancy, this increase in temperature did not compensate for their impaired running performance. Hence, our results suggest that females select higher temperatures during pregnancy to speed up embryogenesis and reduce the period during which they have reduced performance. This strategy may decrease a female's probability of encountering predatory snakes that use the same microhabitats for thermoregulation. Selection of stable temperatures by pregnant females may also benefit embryos, but manipulative experiments are necessary to test this hypothesis.

From tameness to wariness: chemical recognition of snake predators by lizards in a Mediterranean island.

Antipredatory defenses are maintained when benefit exceeds cost. A weak predation pressure may lead insular lizards to tameness. Podarcis lilfordi exhibits a high degree of insular tameness, which may explain its extinction from the main island of Menorca when humans introduced predators. There are three species of lizards in Menorca: the native P. lilfordi, only on the surrounding islets, and two introduced lizards in the main island, Scelarcis perspicillata and Podarcis siculus. In addition, there are three species of snakes, all introduced: one non-saurophagous (Natrix maura), one potentially non-saurophagous (Rhinechis scalaris) and one saurophagous (Macroprotodon mauritanicus). We studied the reaction to snake chemical cues in five populations: (1) P. lilfordi of Colom, (2) P. lilfordi of Aire, (3) P. lilfordi of Binicodrell, (4) S. perspicillata, and (5) P. siculus, ordered by increasing level of predation pressure. The three snakes are present in the main island, while only R. scalaris is present in Colom islet, Aire and Binicodrell being snake-free islets. We aimed to assess the relationship between predation pressure and the degree of insular tameness regarding scent recognition. We hypothesized that P. lilfordi should show the highest degree of tameness, S. perspicillata should show intermediate responses, and P. siculus should show the highest wariness. Results are clear: neither P. lilfordi nor S. perspicillata recognize any of the snakes, while P. siculus recognizes the scent of M. mauritanicus and reacts to it with typical well-defined antipredatory behaviours as tail waving and slow motion. These results rise questions about the loss of chemical recognition of predators during island tameness and its related costs and benefits for lizards of insular habitats. In addition, this highlights the necessity for strong conservation measures to avoid the introduction of alien predators.

Survival and Causes of Mortality for Northern Bobwhites in the Southeastern USA

Long-term studies are imperative to increase our knowledge of northern bobwhite (Colinus virginianus; hereafter bobwhite) demographics. During 1992-2005, we determined survival and cause-specific mortality of bobwhites on 10 study areas in southern Georgia and eastern Alabama, USA.We radio-tagged 7,105 bobwhites and determined 49 annual (Oct-Sep) and 110 seasonal survival estimates to examine spatial and temporal variation in survival. Annual survival for all sites and years combined averaged 0.196 (SE = 0.011) and ranged from 0.08 to 0.40. Over-winter (Oct - Mar) seasonal survival estimates (n = 51) averaged 0.541 (SE = 0.019) and ranged between 0.25 and 0.82, while breeding season (Apr-Sep) survival estimates (n = 59) averaged 0.352 (SE= 0.013) and ranged between 0.13 and 0.59. Over-winter mortality (n = 1,473) of known fates was attributed to avian predation (0.572 ± 0.040), mammal predation (0.265 ± 0.044), harvest (0.156 ± 0.028), snake predation (0.001 ± 0.004) and other (0.005 0.002). Breeding season mortality (n = 2138) was attributed to avian predation (0.613 ± 0.026), mammal predation (0.339 0.049), snake predation (0.037 ± 0.006) and other (0.011 ± 0.004). These over-winter survival estimates were higher than previously published estimates for populations on unmanaged lands and/or heavily harvested populations. On managed lands in the Southeast, bobwhite annual survival rates derived from radio-telemetry were reasonable and provided useful information for management and research.

Survival and Causes of Mortality of Relocated and Resident Northern Bobwhites in East Texas

We estimated survival of 3 groups of northern bobwhites (Colinus virginianus) on a 563-ha intensively managed study area in eastern Texas. During the 3-year study, 155 bobwhites from South Texas and 136 bobwhites from East Texas were captured, radio-marked, and relocated to the study area; 139 bobwhites that were resident on the study area were also captured, radio-marked, and released at the point of capture. There were no differences (P > 0.05) in survival among the 3 groups of bobwhites. However, survival of bobwhites from South Texas were consistently lower than those of the other 2 groups during each year; both bobwhites from East Texas and resident bobwhites survived better than bobwhites relocated from South Texas. Avian predation claimed 57.6% of 243 known-fate birds, mammalian predation and apparent capture stress each caused 9.1 % mortality, while 1.2% of the birds died of snake predation and 14.0% were lost to unidentifiable causes.

Rapid acquisition of antipredatory responses to new predators by an insular lizard

Alien predators may impose a great threat to naive prey. Ibiza wall lizards (Podarcis pityusensis) live in Ibiza, a snake-free island until 2003. We studied the lizards’ discrimination of scents of two invader snakes: one that depredates lizards, the horseshoe whip snake (Hemorrhois hippocrepis), and another that does not, the ladder snake (Rhinechis scalaris). We compared two populations of Ibiza wall lizards: one from the main island of Ibiza, which coexists with both snakes, and another from the nearby snake-free islet of Sal Rossa. Lizards from Ibiza recognized the scent of the horseshoe whip snake and responded with clear antipredatory behaviours. However, they reacted to the scent of the ladder snake similarly to that of the controls (odourless control and pungent scent). Lizards from Sal Rossa did not respond to any of the snakes or the controls. Our results show that lizards can rapidly acquire the ability to react to a novel predator. As only about ten generations of lizards have coexisted with snakes, the most plausible explanation to our results is that lizards have learned to associate the scent of the predatory snake with a threat. This is the first study reporting the rapid acquisition of lizards’ antipredatory responses to the chemical cues of novel predators. However, more research is needed in order to identify the mechanisms implicated in the response. How naive prey acquire antipredator behaviour is both important for basic scientific research and useful for the conservation of native species subjected to biological invasions. The island of Ibiza (Spain) has been free from snakes until their introduction by humans in 2003. We compared the reaction of lizards from Ibiza (where presently three species of snakes cohabitate) and lizards from Sal Rossa (a nearby snake-free islet) to the scent of two snakes (one that feeds on lizards and other that does not). The results were clear: lizards from Ibiza react to the scent of the predatory snake with antipredatory behaviours, while ignoring the scent of the non-predatory snake. Lizards from the snake-free island of Sal Rossa did not react to any of the snakes. Our study shows that lizards can rapidly acquire the ability to react to a completely new type of predator, most likely by learning.

Can protective attributes of artificial refuges offset predation risk in lizards?

AbstractArtificial refuges are often used to supplement habitat in areas where natural shelters have been degraded or removed. Although artificial refuges are intended to support particular species, they may be equally attractive and accessible to others, including predators. We explored the influence of snake predation risk and shelter attributes on the overnight use of different artificial refuges (timber, tiles, and iron) using the predator‐prey relationship between Boulenger's skink, Morethia boulengeri and the curl snake, Suta suta. We collected adult M. boulengeri from two bioregions in south‐eastern Australia: the Riverina, where the two species co‐occur, and the South Western Slopes, where S. suta does not occur. Two adult S. suta were collected for use as chemical donors. We conducted four experiments on overnight refuge choice to determine: (i) predator‐scent avoidance, (ii) artificial refuge preferences, (iii) a trade‐off between a preferred refuge and predator‐avoidance, and (iv) the effect of gap height on refuge preference. We found that skinks avoided predator‐scented refuges in favour of identical, but unscented refuges. Skinks preferred timber refuges, and most skinks maintained this preference when predator‐scent was added. However, when gap height was manipulated, skinks shifted to the refuge with the smallest gap. Skinks displayed complex regional variation in behaviour; skinks from both bioregions avoided predator‐scent, but in the trade‐off experiment, skinks from the South Western Slopes were less likely to avoid predator‐scented timber refuges than those from the Riverina. Our findings suggest that protective refuge attributes, such as small gap height, can offset the risk implied by predator‐scent within a refuge. This study highlights the need to consider predator‐prey interactions when designing and using artificial refuges for habitat restoration or biological monitoring.

Social-bond strength influences vocally mediated recruitment to mobbing.

Strong social bonds form between individuals in many group-living species, and these relationships can have important fitness benefits. When responding to vocalizations produced by groupmates, receivers are expected to adjust their behaviour depending on the nature of the bond they share with the signaller. Here we investigate whether the strength of the signaller-receiver social bond affects response to calls that attract others to help mob a predator. Using field-based playback experiments on a habituated population of wild dwarf mongooses (Helogale parvula), we first demonstrate that a particular vocalization given on detecting predatory snakes does act as a recruitment call; receivers were more likely to look, approach and engage in mobbing behaviour than in response to control close calls. We then show that individuals respond more strongly to these recruitment calls if they are from groupmates with whom they are more strongly bonded (those with whom they preferentially groom and forage). Our study, therefore, provides novel evidence about the anti-predator benefits of close bonds within social groups.

Scales drive detection, attention, and memory of snakes in wild vervet monkeys (Chlorocebus pygerythrus)

Predatory snakes are argued to have been largely responsible for the origin of primates via selection favoring expansion of the primate visual system, and even today snakes can be deadly to primates. Neurobiological research is now beginning to reveal the mechanisms underlying the ability of primates (including humans) to detect snakes more rapidly than other stimuli. However, the visual cues allowing rapid detection of snakes, and the cognitive and ecological conditions contributing to faster detection, are unclear. Since snakes are often partially obscured by vegetation, the more salient cues are predicted to occur in small units. Here we tested for the salience of snake scales as the smallest of potential visual cues by presenting four groups of wild vervet monkeys (Chlorocebus pytherythrus) with a gopher snake (Pituophis catenifer) skin occluded except for no more than 2.7cm, in natural form and flat, the latter to control for even small curvilinear cues from their unusual body shape. Each of these treatments was preceded by a treatment without the snakeskin, the first to provide a baseline, and the second, to test for vigilance and memory recall after exposure to the snakeskin. We found that (1) vervets needed only a small portion of snakeskin for detection, (2) snake scales alone were sufficient for detection, (3) latency to detect the snakeskin was longer with more extensive and complex ground cover, and (4) vervets that were exposed to the snakeskin remembered where they last saw "snakes", as indicated by increased wariness near the occluding landmarks in the absence of the snakeskin and more rapid detection of the next presented snakeskin. Unexpectedly, adult males did not detect the snakeskin as well as adult females and juveniles. These findings extend our knowledge of the complex ecological and evolutionary relationships between snakes and primates.

Cellular basis of anti‐predator adaptation in a lizard with autotomizable blue tail against specific predators with different colour vision

AbstractJuveniles of numerous lizard species have a vividly blue‐coloured tail that likely serves to deflect predator attacks toward the autotomizable tail rather than the lizard's body. The shades of blue colour in the tails of juvenile Plestiodon latiscutatus lizards vary across populations, most notably among those island populations with different predator assemblages. Here, we determine if this intraspecific variation is associated with the differences in colour vision capabilities of lizard predator species. If associated, it would be evidence for local adaptation of tail colour phenotype – natural selection is maximizing the conspicuousness of the tail to the dominant predator species to increase the chance of successfully deflecting attacks. We also use transmission electron microscopy (TEM) to determine the proximate cellular mechanisms that produce the shades of blue in different populations. We revealed that lizard tails with vivid blue reflectance evolved in communities with either weasel or snake predators, two groups of animals with the ability to detect blue wavelengths. However, lizard tail UV reflectance was much higher in populations with only snake predators; that snakes can detect UV, yet weasels cannot, suggests that high UV reflectance is an adaptation to increase tail conspicuousness specifically to snake predators. Finally, a cryptic brown tail evolved independently on the islands where birds are the primary lizard predator. We suggest that because birds have keen visual acuity; a brown, camouflaged phenotype is more advantageous. We also determined through TEM that the thickness of light reflecting platelets in iridophores, and densities of iridophores and xanthophores, predicted the wavelengths and intensity of light reflected by the lizard tail. For example, blue coloration was produced by selective reflection of short wavelengths of light by the thin light reflecting platelets of the iridophore. Greater iridophore density increased light reflectance, while greater xanthophore density decreased light reflectance.

Intercontinental-wide consequences of compromise-breaking adaptations: the case of desert rodents

Desert rodent assemblages from around the world provide convergent, but independent crucibles for testing theory and deducing general ecological principles. The heteromyid rodents of North America and the gerbils of the Middle East and their predators provide such an example. Both sets of rodents face predation from owls and vipers, but the North American species possess unique traits that may represent macroevolutionary breakthroughs: rattlesnakes have infra-red sensitive sensory pits, and heteromyids have cheek pouches. To test their significance, we brought together two gerbils (Middle East), two heteromyid rodents (a kangaroo rat and a pocket mouse; North America) in a common setting (a vivarium in the Negev Desert), and quantified the “opinions” of the rodents towards the North American sidewinder rattlesnake and the Middle Eastern Saharan horned viper and the foraging behavior of each in the face of these snake predators plus owl predators. Gerbils are fairly evenly matched in their anti-predator abilities, while the heteromyids differ widely, and these seem to match well with and may determine the types of mechanisms of species coexistence that operate in the communities of each continent. Evolutionary history, macroevolutionary traits, and risk management therefore combine to determine the characteristics of the organisms and the organization of their communities.

No safety in the trees: Local and species-level adaptation of an arboreal squirrel to the venom of sympatric rattlesnakes

Within some species, squirrels respond to variable selection from venomous snake predators by showing population-level variation in resistance, while between species, some rattlesnakes possess venom that is more effective at overcoming venom resistance in different species of squirrels. A functional evaluation of resistance variation to venom within and between species of squirrels and snakes can link resistance variation to its evolutionary causes across these different evolutionary scales. To do this, we compared the effectiveness of squirrel sera in inhibiting rattlesnake (Crotalus spp.) venom metalloproteinase activity between populations and between species to test for a response to local variation in selection from a single rattlesnake predator and for specialization of two resistant squirrel species to each of their distinct sympatric snake predators. We found that Timber Rattlesnake (Crotalus horridus) venom inhibition by Eastern gray squirrels (Sciurus carolinensis) is higher at a site where the rattlesnakes are present, which suggests selection may maintain venom resistance in populations separated by short distances. Next, we performed a reciprocal cross of venoms and sera from two rattlesnake and two squirrel species. This showed that squirrel resistance is lower when tested against venom from allopatric compared to sympatric rattlesnake species, demonstrating that squirrel inhibitors are specialized to sympatric venom and suggesting a tradeoff in terms of specialization to the venom of a specific species of rattlesnake predator. This pattern can be explained if inhibitors must recognize venom proteins and resistance evolution tracks venom evolution.

Antipredatory reaction of the leopard gecko Eublepharis macularius to snake predators.

Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators (threat-sensitive avoidance) or they have safe but costly general wariness avoiding all potential predators. The level of threat may depend on the predator’s foraging ecology and distribution with the prey with sympatric and specialist species being the most dangerous. We used 2 choice trials to investigate antipredatory behavior of captive born and wild-caught leopard geckos confronted with different snake predators from 2 families (Colubridae, Boidae) varying in foraging ecology and sympatric/allopatric distribution with the geckos. Predator-naïve subadult individuals have general wariness, explore both chemically and visually, and perform antipredatory postures toward a majority of snake predators regardless of their sympatry/allopatry or food specialization. The most exaggerated antipredatory postures in both subadult and adult geckos were toward 2 sympatric snake species, the spotted whip snake Hemorrhois ravergieri, an active forager, and the red sand boa Eryx johnii, a subterranean snake with a sit-and-wait strategy. In contrast, also subterranean but allopatric the Kenyan sand boa Eryx colubrinus did not elicit any antipredatory reaction. We conclude that the leopard gecko possesses an innate general antipredatory reaction to different species of snake predators, while a specific reaction to 2 particular sympatric species can be observed. Moreover, adult wild caught geckos show lower reactivity compared with the captive born ones, presumably due to an experience of a real predation event that can hardly be simulated under laboratory conditions.

A snail-eating snake recognizes prey handedness.

Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes’ dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal.

Do seasonal patterns of rat snake (Pantherophis obsoletus) and black racer (Coluber constrictor) activity predict avian nest predation?

Avian nest success often varies seasonally and because predation is the primary cause of nest failure, seasonal variation in predator activity has been hypothesized to explain seasonal variation in nest success. Despite the fact that nest predator communities are often diverse, recent evidence from studies of snakes that are nest predators has lent some support to the link between snake activity and nest predation. However, the strength of the relationship has varied among studies. Explaining this variation is difficult, because none of these studies directly identified nest predators, the link between predator activity and nest survival was inferred. To address this knowledge gap, we examined seasonal variation in daily survival rates of 463 bird nests (of 17 bird species) and used cameras to document predator identity at 137 nests. We simultaneously quantified seasonal activity patterns of two local snake species (N = 30 individuals) using manual (2136 snake locations) and automated (89,165 movements detected) radiotelemetry. Rat snakes (Pantherophis obsoletus), the dominant snake predator at the site (~28% of observed nest predations), were most active in late May and early June, a pattern reported elsewhere for this species. When analyzing all monitored nests, we found no link between nest predation and seasonal activity of rat snakes. When analyzing only nests with known predator identities (filmed nests), however, we found that rat snakes were more likely to prey on nests during periods when they were moving the greatest distances. Similarly, analyses of all monitored nests indicated that nest survival was not linked to racer activity patterns, but racer‐specific predation (N = 17 nests) of filmed nests was higher when racers were moving the greatest distances. Our results suggest that the activity of predators may be associated with higher predation rates by those predators, but that those effects can be difficult to detect when nest predator communities are diverse and predator identities are not known. Additionally, our results suggest that hand‐tracking of snakes provides a reliable indicator of predator activity that may be more indicative of foraging behavior than movement frequency provided by automated telemetry systems.

Surf and turf: predation by egg-eating snakes has led to the evolution of parental care in a terrestrial lizard

Animals display a great diversity of parental care tactics that ultimately enhance offspring survival, but how such behaviors evolve remains unknown for most systems. Here, we studied the evolution of maternal care, in the form of nest guarding, in a single population of long-tailed sun skink (Eutropis longicaudata) living on Orchid Island (Taiwan). This species typically does not provide protection to its offspring. Using a common garden experiment, we show that maternal care is genetically determined in this population. Through field manipulations, we demonstrate that care provides a significant increase in egg survival on Orchid Island by reducing predation from egg-eating snakes (Oligodon formosanus); this predator is not abundant in other populations of the lizard, which do not display parental care. Finally, using extensive field surveys, we show that the seasonal availability of green sea turtle (Chelonia mydas) nests is the cause for the high abundance of snake predators on Orchid Island, with the snakes consuming lizard eggs when green turtle eggs are not available. Together, these lines of evidence provide the first full demonstration of how predation can trigger the evolution of parental care in a species derived from a non-caring ancestor.