Captive-born collared peccary (Pecari tajacu, Tayassuidae) fails to discriminate between predator and non-predator models

Captive animals may lose the ability to recognize their natural predators, making conservation programs more susceptible to failure if such animals are released into the wild. Collared peccaries are American tayassuids that are vulnerable to local extinction in certain areas, and conservation programs are being conducted. Captive-born peccaries are intended for release into the wild in Minas Gerais state, southeastern Brazil. In this study, we tested the ability of two groups of captive-born collared peccaries to recognize their predators and if they were habituated to humans. Recognition tests were performed using models of predators (canids and felids) and non-predators animals, as well as control objects, such as a plastic chair; a human was also presented to the peccaries, and tested as a separate stimulus. Anti-predator defensive responses such as fleeing and threatening displayswere not observed in response to predator models. Predator detection behaviors both from visual and olfactory cues were displayed, although they were not specifically targeted at predator models. These results indicate that collared peccaries were unable to recognize model predators. Habituation effects, particularly on anti-predator behaviors, were observed both with a 1-h model presentation and across testing days. Behavioral responses to humans did not differ from those to other models. Thus, if these animals were to be released into the wild, they should undergo anti-predator training sessions to enhance their chances of survival

Redução do forrageio do iguana-negro-de-cauda-espinhosa, Ctenosaura similis (Sauria: Iguanidae), na presença de estímulos do predador

The presence of a predator may have direct and indirect effects on the behavior of the prey. Although altered behavior may help prey avoid predators, it also can have a potential impact on critical activities such as foraging. Predator-prey interactions are routinely studied in laboratory-based experiments owing to the perceived difficulties of conducting such experiments in natural settings. We conducted an experimental study under field conditions in Palo Verde National Park in northwestern Costa Rica to assess behavioral responses of Black Spiny-tailed Iguanas (Ctenosaura similis) to the presence of predators and predator cues. Free-roaming iguanas were offered mango in designated areas in the presence of a predator (Boa constrictor), a predator cue (B. constrictor feces), and a control (no predator or predator cue). Results indicate that iguanas reduced their foraging efforts in the presence of both a predator and its cue.A presença de um predador pode exercer efeitos diretos e indiretos sobre o comportamento da presa. Embora a alteração do comportamento possa ajudar a presa a evitar predadores, pode também ter um impacto potencial sobre atividades críticas, como o forrageio. As interações predador-presa são comumente estudadas em experimentos de laboratório devido às dificuldades em conduzir experimentos sob condições naturais. Conduzimos um estudo experimental em campo no Parque Nacional Palo Verde, no noroeste da Costa Rica, para avaliar as respostas dos iguanas-negros-de-cauda-espinhosa (Ctenosaura similis) à presença de predadores e de seus estímulos. Oferecemos manga a iguanas livres em áreas pré-estabelecidas na presença de um predador (Boa constrictor), de um estímulo do predador (fezes de B. constrictor) e em uma áreacontrole (sem predador ou estímulo). Os resultados indicam que os iguanas reduziram seus esforços de forrageio tanto na presença do predador como de seu estímulo

Constriction Behavior, a Key Innovation In Snake Evolution: The Integration of Ethology and Physiology

Among living tetrapod vertebrates, snakes exhibit the most radical shifts in feeding biology and among limbless squamate reptiles, only snakes have undergone a substantial adaptive radiation. The behavioral innovation, constriction, has been associated with the success of this clade. Constriction is a prey restraint behavior that enabled snakes to immobilize and subdue extremely large prey items relative to their own body mass. This behavior pattern is associated with the incredible shifts observed in snake feeding biology from consuming small meals frequently to less frequent feeding on large prey. Although constriction is an ethological homology for the majority of snakes, variations of constriction postures have been documented in many derived snake lineages. Nevertheless, the mechanisms driving behavioral variation are not well understood. In this dissertation, I attempt to use a comparative hierarchical approach to examine constriction behavior at both the ethological and physiological levels in order to better understand the behavioral variation of this key innovation. As reviewed in Part 1, derived snake lineages seem to have several methods with which to restrain prey. Prey restraint methods appear to vary with respect to prey characteristics (size, shape, activity level). On the other hand, intermediate taxa (boas and pythons) are thought to be less variable in the prey restraint phase of feeding. The kinematics of loop application pattern also appears to differ between intermediate and derived snake groups. Derived snakes use the lateral part of their body to wind prey whereas boas tend to bend ventrally around prey. The polarity for variable prey restraint behavior and loop application patterns have not been determined as observations on feeding behavior for basal snake taxa are lacking. I report on stimulus control studies evaluating prey restraint behavior and loop application pattern for basal and intermediate snake taxa in Part 2. Testing for the effects of prey size and status on the prey restraint behavior enabled me to polarize variable prey restraint behavior and loop application pattern. Prey size and status had varying effects on the capture position, prey restraint method, prey restraint time and swallowing time for basal and semi-fossorial boas while individuals of B. constrictor only constricted prey. Looping one or more times around prey was observed during the intraoral transport (swallowing) phase of feeding in the majority of trials for L. bicolor and Erycine snakes (Eryx muelleri, Charina bottae, Lichanura triviragata). Loop application patterns varied across snake taxa with basal and semi-fossorial boas applying loops laterally around prey. Individuals of B. constrictor bent ventrally around prey. The ability to vary prey restraint behavior, in response to prey characteristics and applying loops laterally around prey is probably the ancestral condition in snakes. Intermediate taxa, such a boas exhibit a derived simplified behavioral repertoire. Examining the underlying physiology of a complex motor pattern, such as constriction behavior, can provide a better understanding of the hierarchical structure of organisms in nature. As an ethological homology, constriction behavior provides us with the opportunity to trace evolutionary change at other levels of biological organization and to examine how various levels within a hierarchy relate to one another. Although constriction is an important key innovation associated with the adaptive radiation of snakes, few studies have examined the underlying physiological patterns of this complex motor pattern that may account for the kinematic variability of constriction postures among snakes. In Parts 3 & 4, I comparatively examine the muscle activity patterns during constriction for basal and intermediate snake lineages. I specifically investigated how the underlying physiological mechanisms of constriction correspond to the postural changes observed at the behavioral level using electromyography. Lateral bending and unilateral muscle activity patterns were predominant in the basal taxon, Loxocemus bicolor. Lateral bending and unilateral muscle activity patterns were also observed in derived snake taxa previously documented. Ventral bending and bilateral epaxial muscle activity patterns were predominant in intermediate lineages and present in derived snake lineages. Therefore, similar to prey restraint behaviors, three epaxial muscle activity patterns were observed: 1) mostly lateral bending with unilateral epaxial muscle activity, 2) mostly ventral bending with bilateral muscle activity and 3) mostly lateral and some bilateral bends associated with both unilateral and bilateral epaxial muscle activity, “mixed”. The kinematic and muscle activity patterns correspond with the ethological data in Part 2. Lateral bending and unilateral epaxial muscle activity support the more variable prey restraint behaviors observed in basal and derived snake taxa. Ventral bending and bilateral activity supports the highly stereotyped behavior patterns observed in intermediate snake taxa. A ‘mixed’ kinematic and epaxial activity pattern supports highly variable prey restraint methods as observed from previous research on gopher snakes and kingsnakes. Thus the patterns of epaxial muscle activity underlying constriction behavior can be correlated with the variability in prey restraint postures. In Part 5, I integrate the behavioral, physiological, and ecological differences reported for L. bicolor and Boid snakes, from the stimulus control data and the physiological data collected in this study, to further discuss the origin and evolution of feeding behavior among basal, intermediate and derived snake taxa

Infrared sense in snakes : behavioural and anatomical examinations (Crotalus atrox, Python regius, Corallus hortulanus)

The ability to detect infrared (IR) radiation is a characteristic of boids and pitvipers. These snakes possess highly sensitive IR receptors, often embedded in pit organs, which enable them to locate IR sources independently of visual cues. It was aimed to behaviourally determine IR detection thresholds of two separately evolved IR sensory systems. Electrophysiological studies have been conducted to determine IR detection thresholds in boids and pitvipers. This is the first behavioural study which focuses on the detection thresholds of a pitviper and a boid snake to IR stimuli. Blindfolded Western diamondback rattlesnakes (Crotalus atrox) and Ball pythons (Python regius) were exposed to a moving IR stimulus of constant size and temperature at various distances (C. atrox: 10-160 cm, P. regius: 10-100 cm). The threshold for eliciting distinct behavioural changes during stimulus presentation was used to assess their IR detection thresholds. C. atrox can detect a moving IR stimulus resembling a mouse in temperature and size up to a distance of 100 cm, which corresponds to an irradiance contrast of 3.35 x 10-6 W/cm2. P. regius detected the IR stimulus up to a distance of 30 cm, which corresponds to an irradiance contrast of 3.83 x 10-5 W/cm2. These irradiance contrast detection thresholds reveal a sensitivity 3.2-times higher (C. atrox) or 1.5-times higher (P. regius) than sensitivities found in previous electrophysiological investigations, confirming that behavioural approaches determine sensory sensitivities far more accurately. The differing IR sensitivities of C. atrox and P. regius presumably result from their different habitats, i.e. C. atrox prefers open spaces, whereas P. regius primarily inhabits narrow burrows and rocky areas. Naturally, their IR detection thresholds should be adapted to the distance ranges at which they can be employed usefully. The pit morphology of pitvipers, pythons and boas varies greatly. Pitvipers possess loreal pits, and most pythons have labial pits, whereas most boas lack labial pits or depressions. Pitvipers and pythons are quite well investigated; however, the pit morphology of pit-bearing boas has hardly been examined. The IR sensitive Amazon tree boa (Corallus hortulanus) possesses extraordinarily shaped deep labial scale depressions, which are arranged in a zigzag-formation resulting in backward- and forward-facing scale areas. This unique directional morphology is assumed to be the basis for the IR perception mechanism of C. hortulanus. To build a model for assessing the function of this pit arrangement for IR reception, it was necessary to determine the occurrence, structure and distribution of the IR receptors, i.e. terminal nerve masses (TNMs), within the labial scales. Their structure was investigated by light microscopy and transmission electron-microscopy, whereas the location and size of the TNM areas was determined by succinate dehydrogenase staining. Furthermore, tracing experiments with neurobiotin should have exhibited the central neural projection of the TNMs, however only one trial successfully revealed projections up to the IR processing LTTD. Certain small pores have previously been hypothesised to aid IR reception therefore the surface of the labial scales was inspected with scanning electron microscopy (SEM). These SEM results were combined with a precise 3-D reconstruction of the labial scales, revealing a loose correlation between TNM areas and specific small pores. However, these pores do not seem suitable for reflecting away non-IR wavelengths as hypothesised. Indeed it seems more probable that these pores aid IR reception by homogenising the surface structure, and thereby the surface temperature. To investigate the functional morphology, the SDH staining results were necessary to reconstruct the TNM areas of the supra- and infralabial scales and transfer these onto a plaster head cast of C. hortulanus. This model was used to decode the directional reception characteristics of the 3-D IR field of view, which covers an angular range of up to 300°. It was possible to show that the radiation of an IR source impinges on different proportions of forward- and/or backward-facing TNM areas when coming from different angles, thus giving exact directional information. Additionally, the spatial resolution is enhanced by the sophisticated shape of some labial scales. Moreover, a novel enhancement mechanism was discovered: when a boa turns its head to frontally face an IR source, it receives a sudden drop in IR stimulation at the 10° angle, before receiving doubled IR radiation input when facing the IR source frontally (0° angle). Only then does the IR radiation impinge fully on both sides of the boas head and labial scales. The swift drop at 10° most probably serves as a neural trigger for precise targeting when striking. With C. hortulanus a new IR sensing system has been discovered and the results help to understand how morphology can function to increase the spatial resolution power of sensory systems

From Ambush to Activity: Using Accelerometry to Reveal Cryptic Behaviors of Rattlesnakes and Kangaroo Rats

In my first chapter, I review the behavioral characteristics, functional morphology, biomechanics, and taxonomic diversity of ambush hunting in snakes. Specifically, I discuss and review the decision-making process and behavioral stages involved in choosing an ambush site, the functional morphology and biomechanics behind the predatory strike of an ambush hunting snake, and what is known about the prevalence of ambush hunting within and between snake taxa. In my second chapter, I propose a new method to quantify key aspects of the feeding behavior of three species of viperid snakes (Crotalus spp.) and assess the transferability of classification models across those species. I used open-source software to create species-specific models that classified locomotion, stillness, predatory striking, and prey swallowing with high precision, accuracy, and recall. In addition, we identified a low cost, reliable, non-invasive attachment method for accelerometry devices to be placed anteriorly on snakes, as is likely necessary for accurately classifying distinct behaviors in these species. In my third chapter, I provide a proof-of-concept approach to effectively quantify behavioral patterns of small bodied (< 50 g), nocturnal, and terrestrial free-ranging mammals using large acceleration datasets by combining low-mass, miniaturized animal-borne accelerometers with radiotelemetry and advanced machine learning techniques. We developed a method of attachment and retrieval for deploying accelerometers, a non-disruptive method of gathering observational validation datasets for acceleration data on free-ranging nocturnal small mammals and used these techniques on Merriam’s kangaroo rats to analyze how behavioral patterns relate to abiotic factors. We found that Merriam’s kangaroo rats are only active during the nighttime phases of the diel cycle and are particularly active during later light phases of the night (i.e., late night, morning twilight, and dawn). We found no reduction in activity or foraging associated with moonlight, indicating that kangaroo rats are actually more lunarphilic than lunarphobic. We also found that kangaroo rats increased foraging effort on more humid nights, most likely as a mechanism to avoid cutaneous water loss. My dissertation collectively provides a synthesis of ambush hunting in snakes and highlights the power of biologging technologies to overcome traditional challenges in studying cryptic and nocturnal species

Ecologia e comportamento do bugio vermelho (Alouatta puruensis) em um fragmento florestal em Rolim de Moura, Rondônia

Forest loss and fragmentation affect habitat quality for arboreal species. Among New World monkeys, howlers (Alouatta spp. ) stand out for their ability to survive in fragmented and human-altered forests. This dissertation reports the results of the first study on the ecology and behavior of the Purús red howler monkey (Alouatta puruensis). A social group composed of seven individuals (an adult male, three adult females, a subadult male, a juvenile male, and an infant male) was observed from dawn to dusk during six 15-day periods (=90 days of sampling effort or 1,044 hours of observation) from April to October 2013 in a 2,2-ha forest fragment in Rolim de Moura, state of Rondônia, Brazil. The behavior of the study subjects was recorded using the instantaneous scan sampling method. The study group spent most of the day resting (69% of records), followed by moving (17%) and feeding (12%), and fed on a predominantly folivorous diet (61% of feeding records) that was complemented with flowers (23%) and fruits (15%) belonging to, at least, 36 species. The group ranged over the entire area of the fragment and traveled between 257 and 860 m each day. Quadrupedal walking was by far the most common locomotor mode (97% of records) and sitting was the most common feeding (53%) and resting (57%) posture. The type of food influenced the use of feeding postures. The howlers also adopted a thermoregulatory behavior during resting, increasing the use of heat dissipating postures and the selection of shady places with increasing ambient temperatures. This research also produced the first report of a predation event of a howler monkey by a snake (boa Boa constrictor). In sum, Purús red howler monkeys (A. puruensis) show a behavioral pattern characteristic of the genus.A perda e a fragmentação das florestas alteram a qualidade do habitat para as espécies arborícolas. Dentre os primatas do Novo Mundo, os bugios (Alouatta spp. ) destacam-se por apresentar uma grande capacidade de sobreviver em ambientes fragmentados e alterados pelo homem. Este trabalho relata os resultados do primeiro estudo sobre a ecologia e o comportamento do bugio-vermelho-do-Purús (Alouatta puruensis). Um grupo social composto por sete indivíduos (um macho adulto, três fêmeas adultas, um macho subadulto, um macho jovem e um macho infante) foi observado do amanhecer ao pôr-do-sol durante seis períodos de 15 dias (=90 dias de esforço amostral ou 1. 044 horas de observação) de abril a outubro de 2013 em um fragmento florestal com 2,2 ha em Rolim de Moura, Rondônia, Brasil.O comportamento dos animais foi registrado pelo método de varredura instantânea. O grupo de estudo alocou a maior parte do dia em descanso (69% dos registros), seguido por locomoção (17%) e alimentação (12%), e utilizou uma dieta predominantemente folívora (61% dos registros de alimentação) complementada com flores (23%) e frutos (15%) de, pelo menos, 36 espécies. O grupo utilizou todo o fragmento como área de vida e o percurso diário variou de 257 a 860 m. A caminhada quadrúpede foi o principal tipo de locomoção (97% dos registros) e a postura sentado foi a mais utilizada durante a alimentação (53%) e o descanso (57%). A postura de alimentação foi influenciada pelo tipo de alimento explorado. Os bugios apresentaram um comportamento de termorregulação durante o descanso, aumentando o uso de posturas dissipadoras de calor e a seleção de locais à sombra com o aumento da temperatura ambiente. Por fim, esta pesquisa produziu o primeiro relato de predação de um bugio por uma serpente (jiboia Boa constrictor). Em suma, o bugio-vermelho-do-Purús (A. puruensis) apresenta um padrão comportamental característico do gênero

Snake Species and Their Habitat Preferences on Marsegu Island, West Seram, Maluku, Indonesia

Maluku, an archipelagic region, has unique ecological features that support a high level of biodiversity. One such island in this region is Marsegu Island, located in the Western Seram Regency, which is recognised as a nature reserve and serves as a natural habitat for several species of snakes. This study identifies snake species and analyses habitat preferences on Marsegu Island. Data were collected using the Visual Encounter Survey (VES) method. A total of six snake species from four families were recorded, with Colubridae being the most dominant. Species showed distinct habitat preferences: Xenopeltis unicolor was often found under decaying wood in mangrove areas, while Ahaetulla prasina was associated with Cerbera manghas trees. Larger species, such as Malayopython reticulatus, were found in coral rubble, while Cerberus schneiderii preferred semi-aquatic habitats in mangrove mud. The results suggest that the distribution of snakes on Marsegu Island is strongly influenced by morphological and behavioral adaptations to specific habitat types. This study provides new ecological insights into snake species in mangrove ecosystems and highlights the critical role of habitat conservation in maintaining biodiversity on Marsegu Island

Habitat determinants of golden‐headed lion tamarin (Leontopithecus chrysomelas) occupancy of cacao agroforests: Gloomy conservation prospects for management intensification

Organismal distributions in human‐modified landscapes largely depend on the capacity of any given species to adapt to changes in habitat structure and quality. The golden‐headed lion tamarin (GHLT; Leontopithecus chrysomelas) is an Endangered primate from the Brazilian Atlantic Forest whose remaining populations occupy heterogeneous landscapes consisting primarily of shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. This cash crop can coexist with high densities of native tree species and holds a significant proportion of the native fauna, but its widely extolled wildlife‐friendly status is increasingly threatened by management intensification. Although this potentially threatens to reduce the distribution of GHLTs, the main determinants of tamarin's occupancy of cabrucas remain unknown, thereby limiting our ability to design and implement appropriate conservation practices. We surveyed 16 cabruca patches in southern Bahia, Brazil, and used occupancy modeling to identify the best predictors of GHLT patch occupancy. Key explanatory variables included vegetation structure, critical resources, landscape context, human disturbance, and predation pressure. We found a negative relationship between GHLT occupancy and the prevalence of jackfruit trees (Artocarpus heterophylus), which is likely associated with the low representation of other key food species for GHLTs. Conversely, cabrucas retaining large‐diameter canopy trees have a higher probability of GHLT occupancy, likely because these trees provide preferred sleeping sites. Thus, key large tree resources (food and shelter) are currently the main drivers of GHLT occupancy within cabruca agroecosystems. Since both factors can be directly affected by crop management practices, intensification of cabrucas may induce significant habitat impacts on GHLT populations over much of their remaining range‐wide distribution