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Recording potential predators of herpetofauna in southern Mexico using camera traps and realistic models
Journal of Natural History
Abstract
Knowledge of biotic predator-prey interactions is essential for understanding the role of species in the food web; however, information on these interactions is scarce for most species. Our aim in this study was to gather information on the potential predators of two species of herpetofauna abundant in the rainforest they inhabit, the frog Craugastor loki and the snake Ninia sebae. For this, realistic models of the two species were placed, and monitored using camera traps, in 13 sites located in a forest fragment belonging to a private protected natural area in southern Veracruz in three seasons (dry, rainy and windy) in 2019. In addition, the temporality and seasonality of the events and some behaviours of the potential predators are described. The recorded events were classified into four categories: presence, interest, contact and aggression. For C. loki, 159 events of appearances of potential predators were identified (32 with interaction: 18 events of interest, 2 contact and 12 aggressions). The aggressions were carried out by the mammals Didelphis marsupialis and Peromyscus sp. In the case of N. sebae, 201 appearances of potential predators were identified (75 with interaction: 36 events of interest, 7 contact and 32 aggressions). The aggressions were carried out by 10 species (seven birds and three mammals). Bird predation events towards models of both species occurred during daytime while the attacks by mammals occurred at night. Agonistic behaviours included pecking, biting and urine marking, previously unknown. Events of each category were recorded every season. Our results indicate that C. loki and N. sebae may have more predators than were previously known, and suggest that these species can be an important food resource for different species of birds and mammals in the environments where they live. ARTICLE HISTORY
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The rates of eggs predation in crocodilians can be influenced by the abundance of predators, their activity time, the crocodilian size, and parental care. We evaluated the relationship between crocodilian eggs predation and characteristics of the predatory species (egg search intensity and activity hours), of the nesting females (nest defense), and of the nesting site (habitat characteristics and climatic variables). We evaluated nests with camera traps during the 2014 nesting seasons of Spectacled Caimans (Caiman crocodilus) and American Crocodiles (Crocodylus acutus) in the Biosphere Reserve La Encrucijada, Mexico. We identified a relationship between the defense of the nest and the search for eggs by predators. The number of photographic records of females on the nest increased with the number of photographic records of the egg predators. We observed overlap of activity hours between crocodilian females and egg predators. Females were recorded on the nest only when their predator species was present. In addition, some climatic variables (air temperature and rainfall) and nests characteristics (depth to the first egg and distance to the closest tree) were positively associated with the success of egg predation, depending on the predator species.
Interspecific interactions between vertebrates of different groups are common but also complex and of great importance for community structure. In particular, predation, considered a trophic interaction, plays a significant role in food webs structure and selective effects on prey in natural ecosystems. In this paper we provide new information on the trophic relationship between birds and herpetofauna (reptiles and amphibians) in the complex and biodiverse Usumacinta river basin, through 10 observations recorded between 2012 and 2021. The observations show interactions for feeding purposes of eight bird species, including herons (Tigrisoma mexicanum), jays (Psilorhinus morio), raptors (Caracara cheriway, Pseudastur albicollis, Harpagus bidentatus, Buteo plagiatus), puffbirds (Malacoptila panamensis), and ducks (Dendrocygna autumnalis), with snakes (Coniophanes quinquevittatus), turtles (Chelydra rossignonii, Trachemys venusta), lizards (Iguana iguana, Sceloporus serrifer), crocodiles (Crocodylus moreletii), and frogs (Smilisca baudinii).
Analizamos la diversidad de anfibios del Ejido Tierra y Libertad, Municipio de Jiquipilas, Chiapas, México, el cual se ubica, en más del 40% de su superficie, dentro de la Reserva de la Biosfera La Sepultura (REBISE). Realizamos el trabajo de campo del período de enero de 2016 a abril de 2020, incluidas 980 horas-persona de muestreo sistemático en 11 transectos que abarcan diferentes tipos de hábitat. Documentamos un total de 20 especies de anfibios. Siete especies de anfibios están incluidas en alguna categoría de riesgo: tres en la NOM-059-SEMARNAT-2010 del gobierno federal mexicano, dos en la Lista Roja de Especies Amenazadas de la Unión Internacional para la Conservación de la Naturaleza y dos categorizadas en ambas. La Rana Común de Hojarasca (Craugastor loki) fue la especie más abundante y, junto con otras cuatro especies de anuros, constituyó el 82,1% de la abundancia total observada. La similitud faunística entre transectos se asoció generalmente con la proximidad, la conectividad del corredor forestal y la presencia de agua. La Selva Mediana Subcaducifolia sin disturbio presentó la mayor diversidad alfa, sorprendentemente, los hábitats urbanos y algunos perturbados tuvieron la mayor riqueza de especies. El potrero fue el hábitat menos rico y diverso, por lo que discutimos las consecuencias de la continua expansión de los potreros en las poblaciones de anfibios. Proponemos medidas de conservación destinadas a promover tanto la diversidad de anfibios como la salud humana.
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We analyzed amphibian diversity of the Ejido Tierra y Libertad, Municipality of Jiquipilas, Chiapas, Mexico, 40% of which occurs within the La Sepultura Biosphere Reserve (Reserva de la Biósfera La Sepultura, or REBISE). We conducted fieldwork from January 2016 to April 2020, including 980 person-hours of systematic sampling across 11 transects spanning different habitat types. We documented 20 amphibian species, including the first record of the Yellowbelly Mushroomtongue Salamander (Bolitoglossa flaviventris) for the REBISE. Seven of these amphibian species are included in some risk category: three in the NOM-059-SEMARNAT-2010 of the Mexican federal government, two in the Red List of Threatened Species of the International Union for Conservation of Nature, and two categorized in both. The Common Leaf-litter Frog (Craugastor loki) was the most abundant species, and together with four other anuran species, constituted 82.1% of the total abundance observed. Inter- transect faunal similarity was generally associated with proximity, forest corridor connectivity, and the presence of water. Conserved Semi-Deciduous Forest had the highest alpha diversity, but somewhat surprisingly, urban and some disturbed habitats had the highest species richness. Pasture was the least rich and diverse habitat, however, so we discuss the consequences of ongoing expansion of pastures on amphibian populations. We propose conservation measures intended to promote both amphibian diversity and human health.
Interactions between species and individuals can determine their survival in the wild. Most of the time these relationships are di cult to study in situ by direct observation. However, technology can help collect these data with minimal impact on animals' behaviour. Egg stage is certainly the most vulnerable life stage in crocodilians, but few studies have focused on animal species visiting crocodilian nests and associated egg predation. Herein, we use camera-traps in four Mexican states (Chiapas, Oaxaca, Jalisco, Tabasco) to determine vertebrate species and egg predators associated with wild nests of Caiman crocodilus chiapasius, Crocodylus acutus and Crocodylus moreletii. We recorded 72 species of vertebrates at nesting sites and obtained the rst photographic evidence of crocodi-lian egg predation by Caracara cheriway, Cuniculus paca, Didelphis virginiana and Procyon lotor. We also identi ed commensalism, cooperation, and predation as types of interactions within observed nesting areas, which indicates the importance of crocodilian nesting areas for other wild vertebrates. Finally, we found that crocodi-lian egg predation depends on species richness present in the area of study, as well as crocodilian size. ARTICLE HISTORY
We present a natural history account of the first record of probable predation on the Indian bull frog, Hoplobatrachus tigerinus by the Asian House Shrew, Suncus murinus from Morang district, Nepal. The present communication provides an example of a nearly equal-sized predator-prey interaction in a natural ecosystem and provides interesting information on the natural history of these taxa.
Scavenging of carrion is essential to terrestrial ecosystems and can shape food webs and behavior. The prevalence and importance of scavenging has often been underestimated and overlooked in food web studies. Small-mammal carrion is even less studied and difficult to estimate, especially in the Neotropics. This project explored small-mammal carcass scavenging in a Neotropical, mid-elevation rainforest, and specifically studied the rate of carcass removal by scavengers, how the conspicuousness and weight of carcasses affect scavenging, and what vertebrate scavengers utilize this carrion resource. I deployed 194 mouse carcasses of various weights, above and below the leaf litter, and surveyed them daily until disappearance. I paired each carcass with a trail camera to help identify vertebrate scavengers. A general linear model analysis showed that most mouse carcasses disappeared within 1 to 2 days. Carcasses above the leaf litter were removed quicker and larger mice generally lasted longer. Only 6.25 % of the carcasses were removed by vertebrates. Most carcasses were removed by something too small to trigger the trail cameras, likely scarab beetles. The results of this study show that small-mammal carcasses are a sought-after resource in Neotropical forests, and that invertebrates are able to quickly hoard and secure small carrion more efficiently than vertebrate scavengers. A better understanding of scavenging ecology in Neotropical forests will help in developing a broader framework of the trophic interactions within and across ecosystems.
Camera trap technology has galvanized the study of predator–prey ecology in wild animal communities by expanding the scale and diversity of predator–prey interactions that can be analysed. While observational data from systematic camera arrays have informed inferences on the spatiotemporal outcomes of predator–prey interactions, the capacity for observational studies to identify mechanistic drivers of species interactions is limited.
Experimental study designs that utilize camera traps uniquely allow for testing hypothesized mechanisms that drive predator and prey behaviour, incorporating environmental realism not possible in the laboratory while benefiting from the distinct capacity of camera traps to generate large datasets from multiple species with minimal observer interference. However, such pairings of camera traps with experimental methods remain underutilized.
We review recent advances in the experimental application of camera traps to investigate fundamental mechanisms underlying predator–prey ecology and present a conceptual guide for designing experimental camera trap studies.
Only 9% of camera trap studies on predator–prey ecology in our review use experimental methods, but the application of experimental approaches is increasing. To illustrate the utility of camera trap‐based experiments using a case study, we propose a study design that integrates observational and experimental techniques to test a perennial question in predator–prey ecology: how prey balance foraging and safety, as formalized by the risk allocation hypothesis. We discuss applications of camera trap‐based experiments to evaluate the diversity of anthropogenic influences on wildlife communities globally. Finally, we review challenges to conducting experimental camera trap studies.
Experimental camera trap studies have already begun to play an important role in understanding the predator–prey ecology of free‐living animals, and such methods will become increasingly critical to quantifying drivers of community interactions in a rapidly changing world. We recommend increased application of experimental methods in the study of predator and prey responses to humans, synanthropic and invasive species, and other anthropogenic disturbances.
Camera traps are a unique survey tool used to monitor a wide variety of mammal species. Camera trap (CT) data can be used to estimate animal distribution, density, and behaviour. Attractants, such as scent lures, are often used in an effort to increase CT detections; however, the degree which the effects of attractants vary across species is not well understood. We investigated the effects of scent lure on mammal detections by comparing detection rates between 404 lured and 440 unlured CT stations sampled in Alberta, Canada over 120 day survey periods between February and August in 2015 and 2016. We used zero-inflated negative binomial generalized linear mixed models to test the effect of lure on detection rates for a) all mammals, b) six functional groups (all predator species, all prey, large carnivores, small carnivores, small mammals, ungulates), and c) four varied species of management interest (fisher, Pekania pennanti; gray wolf, Canis lupus; moose, Alces alces; and Richardson’s ground squirrel; Urocitellus richardsonii). Mammals were detected at 800 of the 844 CTs, with nearly equal numbers of total detections at CTs with (7110) and without (7530) lure, and variable effects of lure on groups and individual species. Scent lure significantly increased detections of predators as a group, including large and small carnivore sub-groups and fisher specifically, but not of gray wolf. There was no effect of scent lure on detections of prey species, including the small mammal and ungulate sub-groups and moose and Richardson’s ground squirrel specifically. We recommend that researchers explicitly consider the variable effects of scent lure on CT detections across species when designing, interpreting, or comparing multi-species surveys. Additional research is needed to further quantify variation in species responses to scent lures and other attractants, and to elucidate the effect of attractants on community-level inferences from camera trap surveys.
Crypsis, or the ability of an animal to avoid detection by other animals, is strongly impacted by an animal’s colouration and pattern. Crypsis may be especially important for ambush foragers, which spend much of their time above ground and therefore benefit from being inconspicuous to predators and prey. The purpose of this study was to investigate the effect of rattlesnake skin colouration on the likelihood of it being detected and attacked by a predator, on the latency (time) to attack, and on the attack frequency on each physical body section of the models. Clay models representing four commonly observed rattlesnake colour morphs (light, dark and two intermediate colour patterns) were deployed in two different habitat types (wooded area and open field), and the marks made on the models by predators were quantified over time. We found that light snake models, which have little contrast with substrate, were less likely to be attacked and were attacked later than darker model types, which have higher contrast with substrate. Predators attacked the various body segments of the models at similar frequencies. Our data suggest dark‐coloured rattlesnakes, which have the most contrast with the golden‐coloured grasses and therefore have the lowest crypsis, are most at risk from predation. Using a combination of physical snake models and camera traps, our study showed that snakes with dark colouration, regardless of habitat type, experienced a higher risk of predation and were attacked earlier in the study than light coloured snakes (i.e. snakes that contrasted less with the surrounding substrate). Interestingly, despite using a venomous species as our model, snake predators showed no preference as to which section of the snake body was targeted for attack.
Clay models of live animals are often used by behavioral ecologists and ethologists to study prey-predator interactions under field conditions. This technique has limitations, however, and often models are displayed in the field for long periods of time without distinguishing between daytime and nighttime attacks. We compared day and night predation rates on lizard-shaped clay models in a temperate ecosystem in northwest Italy. We placed 206 lizard models in two adjacent habitats (i.e., a mixed broadleaf woodland and along an adjacent ecotone) and checked them every morning and evening for three consecutive days (i.e., for 72 h). The model head was attacked more than expected by chance, indicating that predators were perceiving the models as true prey items. The overall observed predation rate was 18% (39/206) and was similar between the two habitats; however, models were attacked more than twice as often during daytime versus nighttime with 28 attacks (71%) during the day and 11 attacks (29%) during the night. Mammal predators attacked the models with similar frequencies during both daytime and nighttime. These findings indicate that, at least in our study area, the predation rate on terrestrial lizards differs between day and night and that mammals are diurnal potential predators of lizards.
El establecimiento de Áreas Protegidas Privadas (APPs) es una de las estrategias para la protección de la biodiversidad ante la modificación del hábitat en bosques tropicales; sin embargo, su importancia en conservación ha sido poco evaluada. En este trabajo estimamos la importancia de un APP conocida como Área de Protección y Desarrollo de Ceratozamia (APDC) para la conservación de anfibios y reptiles, en comparación con otras dos APPs (Parque Ecológico Jaguaroundi y el Parque Ecológico Tuzandepetl) en el sur de Veracruz, México. El APDC tiene una extensión de 100 hectáreas: 50 ha de bosque tropical subcaducifolio y 50 ha de pastizal. Los muestreos para este estudio se realizaron entre los años 2015 y 2016, empleando el método de búsqueda libre restringida por tiempo (esfuerzo de muestreo total = 768 horas-persona). En total, en el APDC se registraron 20 especies de anfibios y 35 de reptiles. El 20% de los anfibios y el 32% de reptiles registrados se encuentran en alguna categoría de riesgo de extinción según la Norma Oficial Mexicana NOM-059-SEMARNAT-2010, dos especies de anfibios y una especie de reptil están incluidas en la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza (UICN), mientras que el 12% de los reptiles se encuentran en categoría de vulnerabilidad ambiental alta. El APDC tuvo la mayor riqueza de especies en comparación con las otras dos APPs. Los anfibios tuvieron una composición relativamente similar entre las APPs, mientras que para los reptiles la composición de especies tendió a ser distinta. Nuestros resultados indican que por la riqueza de especies y el número de especies amenazadas de extinción y de especies no evaluadas por la UICN que alberga, el APDC contribuye a la conservación de herpetozoos en una zona altamente transformada del sur de México, en conjunto con las otras dos APPs, donde el Área Natural Protegida bajo régimen gubernamental más cercana (Reserva de la Biosfera Los Tuxtlas) se localiza a 50 km.
New prey items are reported in snakes that were found run over during night road trips, belonging to the families Colubridae, Dipsadidae, Elapidae and Viperidae from the Yucatán Peninsula, Mexico.
Clay models are realistic replicas of live animals that are frequently used in ecological and ethological field studies. These kind of models, usually made from plasticine, are malleable, easy to shape, colour and relative inexpensive. In addition, plasticine models retain marks on their surface allowing the identification of the predator and of the body part of the prey that was attacked. In this short review we retrieved and analysed a preliminary list of studies published until December 2017, that used clay replicas of amphibians in ecological field studies. Overall 25 publications were analysed. The first scientific paper using amphibian clay models was published in 1994, but only after the year 2005 the use of clay replicas became frequent in herpetological field researches. The majority of studies were performed in tropical or subtropical ecosystems of Central and South America, and only a relative small number of studies were executed in temperate forests of North America and Europe. The most studied family was Dendrobatidae with nine species. In Urodela the Plethodontidae, with four species, was the most studied family. After the analysis of the main features concerning technical aspects, geographic distribution and temporal trend of these kind of studies, the pros and cons of the use of amphibian clay models are synthetically discussed.
Artificial prey techniques—wherein synthetic replicas of real organisms are placed in natural habitats—are widely used to study predation in the field. We investigated the extent to which videography could provide additional information to such studies. As a part of studies on aposematism and mimicry of coral snakes ( Micrurus ) and their mimics, observational data from 109 artificial snake prey were collected from video-recording camera traps in three locations in the Americas ( terra firme forest, Tiputini Biodiversity Station, Ecuador; premontane wet forest, Nahá Reserve, Mexico; longleaf pine forest, Southeastern Coastal Plain, North Carolina, USA). During 1,536 camera days, a total of 268 observations of 20 putative snake predator species were recorded in the vicinity of artificial prey. Predators were observed to detect artificial prey 52 times, but only 21 attacks were recorded. Mammals were the most commonly recorded group of predators near replicas (243) and were responsible for most detections (48) and attacks (20). There was no difference between avian or mammalian predators in their probability of detecting replicas nor in their probability of attacking replicas after detecting them. Bite and beak marks left on clay replicas registered a higher ratio of avian:mammalian attacks than videos registered. Approximately 61.5% of artificial prey monitored with cameras remained undetected by predators throughout the duration of the experiments. Observational data collected from videos could provide more robust inferences on the relative fitness of different prey phenotypes, predator behavior, and the relative contribution of different predator species to selection on prey. However, we estimate that the level of predator activity necessary for the benefit of additional information that videos provide to be worth their financial costs is achieved in fewer than 20% of published artificial prey studies. Although we suggest future predation studies employing artificial prey to consider using videography as a tool to inspire new, more focused inquiry, the investment in camera traps is unlikely to be worth the expense for most artificial prey studies until the cost:benefit ratio decreases.
Feeding events of unsual prey items are rarely recorded in the field. Here we report diet resources for eleven Neotropical bird species. We include an observation of scavenging behavior for the Black Hawk-Eagle (Spizaetus tyrannus), the first record of wood consumption by the Crimson-fronted Parakeet (Psittacara finschi), moss consumption by the Mealy Parrot (Amazona farinosa), mycophagy by the Yellow-faced Grassquit (Tiaris olivaceus), and reports of unknown or uncommon diet sources for the Ruddy Turnstone (Arenaria interpres), the Rufescent Tiger-Heron (Tigrisoma lineatum), the Gray-headed Kite (Leptodon cayanensis), the White-tailed Kite (Elanus leucurus), the Lesson's Motmot (Momotus lessonii), the White-crowned Parrot (Pionus senilis), and the Tropical Kingbird (Tyrannus melancholicus). Palabras clave: foraging behavior, mycophagy, nestling predation, omnivorous diet, scavenging behavior. Resumen Los eventos de alimentación en aves son rara vez observados y registrados en el campo. En esta nota reportamos nuevos recursos alimenticios para once especies de aves Neotropicales. Incluimos una observación de comportamiento de tipo carroñero en Spizaetus tyrannus, el primer reporte de Psittacara finschi comiendo madera, Amazona farinosa alimentándose de musgo y micofagia en Tiaris olivaceus. Además reportamos fuentes de alimento desconocidas, o poco comunes, para Arenaria interpres, Tigrisoma lineatum, Leptodon cayanensis, Elanus leucurus, Momotus lessonii, Pionus senilis y Tyrannus melancholicus.
[Bulletin of the Chicago Herpetological Society 54(1): 4-8] The variable coral snake (Micrurus diastema) is distributed along the Atlantic versant from central Veracruz, Mexico, through the Yucatán Peninsula, Belize, and northern Guatemala to northwestern Honduras (Campbell and Lamar, 2004; Heimes, 2016). It preys primarily on small snakes, but lizards, caecilians and swamp eels have also been reported (Greene, 1973; Blaney and Blaney, 1978; Seib, 1985; Lee, 1996; Roze, 1996; Campbell, 1998; Rodriguez et al., 1998; Campbell and Lamar, 2004; Heimes, 2016; Köhler et al., 2016). We examined the stomach contents of M. diastema specimens from Mexico (n = 23) and Guatemala (n = 1) within the University of Illinois Museum of Natural History Herpetology Collection (UIMNH). Prey items found in the gastrointestinal tracts of three Micrurus diastema diastema specimens are reported herein.
• Identification of pollen vectors is a fundamental objective of pollination biology. The foraging and social behavior of these pollinators has profound effects on plant mating, making quantification of their behavior critical for understanding the ecological and evolutionary consequences of different pollinators for the plants they visit. However, accurate quantification of visitation may be problematic, especially for shy animals and/or when the temporal and spatial scale of observation desired is large. Sophisticated heat‐ and movement‐triggered motion‐sensor cameras (“camera trapping”) provide new, underutilized tools to address these challenges. However, to date, there has been no rigorous evaluation of the sampling considerations needed for using camera trapping in pollination research.
• We measured the effectiveness of camera trapping for identifying vertebrate visitors and quantifying their visitation rates and foraging behavior on Banksia menziesii (Proteaceae). Multiple still cameras (Reconyx HC 500) and a video camera (Little Acorn LTL5210A) were deployed.
• From 2,753 recorded visits by vertebrates, we identified five species of nectarivorous honeyeater (Meliphagidae) and the honey possum (Tarsipedidae), with significant variation in the species composition of visitors among inflorescences. Species of floral visitor showed significant variation in their time of peak activity, duration of visits, and numbers of flowers probed per visit. Where multiple cameras were deployed on individual inflorescences, effectiveness of individual still cameras varied from 15% to 86% of all recorded visits. Methodological issues and solutions, and the future uses of camera traps in pollination biology, are discussed.
• Conclusions and wider implications: Motion‐triggered cameras are promising tools for the quantification of vertebrate visitation and some aspects of behavior on flowers. However, researchers need to be mindful of the variation in effectiveness of individual camera traps in detecting animals. Pollinator studies using camera traps are in their infancy, and the full potential of this developing technology is yet to be realized.
Background: Many intriguing questions about predator-prey interactions can be addressed by using clay models
of prey animals. These are placed in the field to test predators’ avoidances or preferences (testing e.g. color or
shape) or to gain insights into predator identity. Modeling clay allows teeth, beak and jaw marks to remain on the
model for identification. First used 30 years ago, clay models are now widely deployed. Ever since, the complexity
of hypotheses, modeled species as well as the number of clay models used per study has increased. Although clay
models are a valuable research tool, the method has limitations. Some questions cannot be addressed with these
experiments, yet there is potential for improvement.
Main body: We focus on the following aspects that need attention for clay model studies (CMS) in the future: (1)
Use of proper clay materials, (2) how to standardize attack identification, (3) limitations of clay model studies, (4) use
of clay models beyond predation experiments and (5) the next generation of clay model studies.
Conclusion: We conclude that certain aspects of the clay model paradigm urgently need greater standardization.
We advocate the use of harmless clay products and non-toxic inks, as well as having a neutral person to evaluate
the marks left in the clay against pre-defined inclusion criteria. Further we suggest to use experimental data more
cautiously in respect to evolutionary explanations, to use clay studies in detection experiments and to develop
methods for attacker identification based on predator salivary DNA.
Keywords: Ecological studies, Predator-prey interactions, Predator salivary DNA
Neo-taphonomic studies of carnivores are commonly used to explain the formation processes of Pleistocene faunal assemblages. However, these works have been developed mostly with large carnivores—e.g. hyenas. On the contrary, small and medium-sized carnivores have been scarcely studied in spite of their presence in most of the archaeological sites. Here, we present a study trying to characterise the wild predator behaviour from a taphonomic perspective, describing consumption patterns on 23 small-sized ungulate carcasses eaten by red foxes (Vulpes vulpes) during a 2-year period in the Spanish Pyrenees. The aim of this work, therefore, is to characterise taphonomically this predator and to obtain data to distinguish them from other most common carnivores. For that, a combination of observational data from photo/video-trap and taphonomic analyses was compiled, allowing us to control variables like seasonality and time of consumption, as well as the spatial dispersion of skeletal remains. The initial interest by foxes lies in the disassembly of the anatomical elements and their transport to secluded places giving rise to dispersion of bones. Regarding to seasonality, bone modification increases at the end of winter/spring time, and proportionally, the time of consumption decreases. When the carcass is complete, viscera seem to be an important resource, followed by meat covering femur and humerus. This phenomenon causes significant damage on axial bones (mainly fractures and tooth marks), and to a lesser extent, on pelvis and proximal stylopodials.
Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.
The present study was aimed to determine the population characteristics of the House shrew, Suncus murinus, in rural commensal habitats of Pothwar, Pakistan. The trapping campaign was conducted in four village sites of Pothwar on a seasonal basis from March 2012 through February 2014. In each village, snap traps were set in three types of structures (including, village households, shops and farm houses). The results showed that the shrew population in the rural human habitations had an unbiased sex ratio. Reproductively active individuals were present throughout the year. Reproductively active females outnumbered the inactive individuals. The species was predominantly eating animal food (mainly insects) in its diet along with the sufficient amount of plant matter. Overall, these results indicated that in commensal conditions shrew populations had diversity in their diet with the relatively continuous reproductive activity.
A juvenile Bothrops asper (Terciopelo) collected in Tamaulipas, Mexico, is identified as the westernmost locality for the species range-wide. We review and map the distribution in Tamaulipas and adjacent areas of San Luis Potosí and Veracruz, Mexico, based on museum and literature records. The specimen was dissected and its stomach contained Cryptotis parva, a novel prey item for the species. We review previous literature reports for specific prey items.
An understanding of animal behaviour is important if conservation initiatives are to be effective. However, quantifying the behaviour of wild animals presents significant challenges. Remote-sensing camera traps are becoming increasingly popular survey instruments that have been used to non-invasively study a variety of animal behaviours, yielding key insights into behavioural repertoires. They are well suited to ethological studies and provide considerable opportunities for generating conservation-relevant behavioural data if novel and robust methodological and analytical solutions can be developed. This paper reviews the current state of camera-trap-based ethological studies, describes new and emerging directions in camera-based conservation behaviour, and highlights a number of limitations and considerations of particular relevance for camera-based studies. Three promising areas of study are discussed: (1) documenting anthropogenic impacts on behaviour; (2) incorporating behavioural responses into management planning and (3) using behavioural indicators such as giving up densities and daily activity patterns. We emphasize the importance of reporting methodological details, utilizing emerging camera trap metadata standards and central data repositories for facilitating reproducibility, comparison and synthesis across studies. Behavioural studies using camera traps are in their infancy; the full potential of the technology is as yet unrealized. Researchers are encouraged to embrace conservation-driven hypotheses in order to meet future challenges and improve the efficacy of conservation and management processes.
RESUMEN Se propone una técnica nueva de fototrampeo para contabilizar e identificar insectos y reptiles, considerando que con las técnicas y equipo convencionales no suelen ser registrados por la limitada capacidad que tienen las lentes para enfocar animales pequeños y cercanos o detectar sus sutiles movimientos. La técnica permite registrar a los polinizadores diurnos y nocturnos de especies de interés, a los insectos con potencial de plaga, registrar la actividad de reptiles y su capacidad de dispersión de semillas, entre otros. Palabras clave: Registro de rastros, abundancia, cámara trampa, patrón de actividad. ABSTRACT A new photo trapping technique is proposed to count and identify insects and reptiles, taking into consideration that with the conventional techniques and equipment they are usually not recorded because of the limited capacity that the lenses have to focus on small and nearby animals or to detect their subtle movements. The technique allows recording diurnal and nocturnal pollinators of species of interest, insects with the potential to be pests, and recording the activity of reptiles and their capacity for seed dispersion, among others.
The genus Didelphis contains six species of marsupials that are found only in the Americas. Commonly referred to as opossums, Didelphis species have been widely studied over the years and possess a number of features that make them suitable for semi-intensive production. Rearing any species for production requires a solid knowledge on species biology and behaviour. The following paper is a review of the state of knowledge on Didelphis species and focuses on the natural history, animal behaviour, diet and digestion. It further highlights the gaps of information on this genus. In total over 140 years of documented literature on the species was examined and synthesized. It was found that much is known on the natural history of the genus, except for the neo-tropical species which are yet to be studied. Animal behaviour and digestion were both intensively studied in the 1900s, but focussed almost solely on captive Didelphis virginiana specimens, with limited research on its congeners. Although much work was completed over a wide span of years, there remain a number of areas still requiring investigation, particularly for the neo-tropical species of Didelphis that live in South America and the Caribbean.
We review the use of clay models to explore questions about predation rates on small vertebrate taxa that are typically difficult to observe directly. The use of models has a relatively long history and we examine the range of taxa studied, which includes squamate reptiles, amphibians, mammals and birds. Within this review, we have also included studies of model eggs, which are used in nest predation studies. We review the questions that have been asked and the interpretations arising from the data. The use of clay model animals has provided us with insights into how differences in prey morphology, size, and colour influence the rate at which they are attacked by predators. This allows us insights into the ecological, behavioural and evolutionary selective pressures of different predators on small vertebrate prey, including analysis of what characteristics predators target and how predators approach their prey (e.g. which part of the body is attacked). Further available interpretations include how regional and habitat variation influences predation events on models. We also briefly discuss the potential for clay models to study interspecific sociality and competition. Finally, we review the problems and limitations with the method and make some suggestions for further studies and amendments to help standardize this creative tool for ecological research.
Interspecific competition between sympatric carnivores can have a profound effect on the structure, function and composition of ecosystems. Interspecific competition is often asymmetrical and the smaller carnivore is usually affected the most. We investigated the behavioural responses of two native species, the larger Tasmanian devil (Sarcophilus harrisii) and the smaller spotted-tailed quoll (Dasyurus maculatus) to each other’s odour and to that of an introduced predator, the feral cat (Felis catus), in north-west Tasmania, Australia. We used an experimental array of camera traps, in which carnivore scats were added as treatments. Behavioural responses exhibited by devils and quolls are indicative of a dominant predator-mesopredator relationship and suggest the potential for interspecific competition. The larger predator, the devil, was as vigilant at quoll odour as at control camera traps, but showed decreased vigilance at cat odour and did not avoid cat or quoll odours. The smaller predator, the spotted-tailed quoll, increased its vigilance near devil odour compared to control camera traps but did not avoid it. This experiment shows that assessing the behavioural responses of sympatric carnivores to each other’s odour can help understand predator interactions and reveal the potential for interspecific competition. Understanding these interactions is crucial in managing and conserving carnivores.
Significance statement
Animals navigate through an environment full of faecal odours left by predators, competitors and conspecifics. These odours provide information on both the immediate presence and the indirect risk of encountering a predator or an aggressive competitor. Tasmania’s largest predator, the Tasmanian devil, coexists with the smaller spotted-tailed quoll and the introduced feral cat. We tested the behavioural responses of Tasmanian devils and spotted-tailed quolls to each other’s faecal odour and to cat faecal odour. Behavioural patterns exhibited by predators in this experiment are indicative of a dominant predator-mesopredator relationship and suggest the potential for interspecific competition. Knowledge of the ecological interactions amongst sympatric carnivores can aid managers in making more informed decisions when trying to achieve specific conservation goals.
Se documentan 3 eventos de depredación de herpetozoos por arañas de las familias Ctenidae y Theraphosidae en diferentes sitios de Veracruz, México. Estas observaciones representan el primer caso de depredación por arañas sobre la especie de anuro Craugastor pygmaeus (familia Craugastoridae), la lagartija Scincella cherriei (Scincidae) y la serpiente Ninia sebae (Colubridae).
Herpetotheres cachinnans is a Neotropical falcon species found in a variety of forested to semi-open habitats from Mexico to Argentina. Despite H. cachinnans being known to consume a variety of prey types, snakes comprise the majority of its diet in terms of taxonomic richness and frequency. Here, we present a detailed review about prey records of H. cachinnans. A total of 122 prey records were compiled from 73 literature references and authors' records. Snakes were the most common prey, with 94 records (77%). Analysis of 24 stomach contents (from literature and author's records) show that 71% contained remains of at least one snake, and 62.5% had snakes exclusively. A snake-based diet seems to be uncommon in raptors, and H. cachinnans is the only one presenting such degree of diet specialization in the Neotropics.
Opossums are considered natural predators of snakes and possess resistance to the venom of some viperids. The resistance of Didelphis to Crotalus venom has been demonstrated through biochemical and immunologi-cal assays. However, systematic observations on the behavior of adult Didel-phis preying on venomous snakes have never been conducted. In this study the predatory and defensive behaviors of Didelphis marsupialis and Crotalus durissus, respectively, were analyzed in captivity. Defensive strategies showed by snakes included immobility, flight attempts, coiling, cocking, rattling, and counterattack with strikes and bites. The most common defensive behavior of the rattlesnakes was immobility. The way the opossums attacked was classified in three categories, depending on the defensive reactions presented by the snakes. On all occasions when the opossums were bitten, the injection of venom apparently did not affect the predation. The great ability in capturing and handling Crotalus durissus together with the apparent great tolerance to the venom shown by Didelphis marsupialis when preying on these snakes confirms the existent biochemical and immunological data about the resistance of opossums to crotalic venoms. In this way our data strongly reinforce the supposition that this species is an effective snake predator in nature.
Clay model experiments are commonly used to measure natural rates of predation and have become an important method in studying predator avoidance of aposematic frogs. Previous clay model experiments have demonstrated that conspicuous coloration in dendrobatid frogs is an effective deterrent to avian predators. It is generally assumed that predators recognize clay models as frogs, but few studies have examined this hypothesis. Certain aposematic frogs are similar in color to fruits on the forest floor, and it is possible that frugivorous or omnivorous birds perceive clay models as fruit. In the present study, we further investigate aposematism in Oophaga pumilio and specifically examine the importance of model shape and color. We assessed natural avian predation rates using clay models, which were either red or brown in color, and frog or ball (fruit) shaped. Overall, avian predation was significantly higher on red ball-shaped models when compared to red frog-shaped models. Brown frogs were also more likely to be preyed upon than red frogs. The omnivorous Great Tinamou (Tinamus major), however, exhibited no preference for frog color. Feeding naturally on fruits and seeds, tinamous in our study preferred and attacked red ball models more frequently, suggesting that they recognized these models as fruits. Collectively, our results provide evidence that birds distinguish between shapes and colors when making decisions about predation and that these attacks are dependent on the dietary preference of the predator. Clay model studies should take into account both color and shape of models, and consider that predation rates are likely dependent on the species assemblages present at a location and their specific dietary preferences.
The identification and analysis of ecological guilds have been fundamental to understand the processes that determine the structure and organization of communities. However, reviewing studies that have tried to categorize species into trophic guilds we found many different criteria on which such categorizations are based; consequently, a single species may have several guild designations, limiting its accuracy and applicability. In this paper we propose a classification scheme for trophic guilds as a first step to establish a common terminology. For this purpose we considered 1502 species of mainland birds and mammals from North America (Mexico, USA, and Canada). This classification takes into account 3 main criteria to identify each guild: main food type, foraging substrate and activity period. To determine the trophic guilds and assign species to them, we performed a cluster analysis to classify species according to their similarities in feeding patterns. The resulting hierarchical classification distinguishes 6 main levels of organization, which may occur in different combinations among taxonomic groups and sites: 1) taxon (e. g., birds or mammal), 2) diet (e. g. granivore, insectivore), 3) foraging habitat (e. g., terrestrial, arboreal), 4) substrate used for foraging (e. g., ground, foliage), 5) foraging behavior (e. g., gleaner, hunter), and 6) activity period (e. g., nocturnal, diurnal). We identified 22 guilds for birds and 27 for mammals. This approach aims to group together species that use similar resources in a similar way, and extend the usefulness of this approach to studies intend to analyze the organization of biotic communities.
This is the only field guide to provide comprehensive coverage of the mammals of Central America and southeast Mexico. The fully revised second edition includes 21 new species, as well as updated illustrations and distribution maps. Each species account provides measurements, descriptions, and comparisons with similar species, and is accompanied by a range map showing where the species can be found in the region. The 49 full-color animal plates contain similar species portrayed to scale on the same plate, with tracks and feet shown on the facing-page. 4 new full-color maps provide visual views of parks and protected areas, biomes, elevations and habitat loss, as well as a political map of the region. The book also features a detailed introduction with sections on how and where to find mammals and a listing of the most endangered species in the region.
This completely new in-depth field guide covers the 1070 bird species, including North American migrants, found in Mexico, Guatemala, Belize, El Salvador, Honduras, and western Nicaragua. More than 180 species are endemic to this region. Richly illustrated with 71 colour plates and additional black-and-white drawings, it describes the birds' appearance, voice, habitat, behaviour (including nests and eggs), and distribution. Introductory chapters give essential background information. Once you have this book, you will wonder how you ever got by without it.
Traditional surveys for small mammals and herpetofauna require intensive field effort because these taxa are often difficult to detect. Field surveys are further hampered by dynamic environmental conditions and dense vegetative cover, which are both attributes of biodiverse wet meadow ecosystems. Camera traps may be a solution, but commonly used passive infrared game cameras face difficulties photographing herpetofauna and small mammals. The Adapted-Hunt Drift Fence Technique (AHDriFT) is a camera trap and drift fence system designed to overcome traditional limitations, but has not been extensively evaluated. We deployed 15 Y-shaped AHDriFT arrays (three cameras per array) in northern Ohio wet meadows from March 10 to October 5, 2019. Equipment for each array cost approximately US$1,570. Construction and deployment of each array took about three hours, with field servicing requiring 15 minutes per array. Arrays proved durable under wind, ice, snow, flooding and heat. Processing two-weeks of images of 45 cameras averaged about 13 person-hours. We obtained 9,018 unique-capture events of 41 vertebrate species comprised of 5 amphibians, 13 reptiles (11 snakes), 16 mammals and 7 birds. We imaged differing animal size classes ranging from invertebrates to weasels. We assessed detection efficacy using expected biodiversity baselines. We determined snake communities from three years of traditional surveys and possible small mammal and amphibian biodiversity from prior observations and species ranges and habitat requirements. We cumulatively detected all amphibians and 92% of snakes and small mammals that we expected to be present. We also imaged four mammal and two snake species where they were not previously observed. However, capture consistency was variable by taxa and species, and low-mobility species or species in low densities may not be detected. In its current design, AHDriFT proved to be effective for terrestrial vertebrate biodiversity surveying.
Using an innovative approach to study the neural bases of psychiatric disorders, this study investigated the behavioral, morphological and pharmacological bases of panic attack-induced responses in a prey-versus-coral snake paradigm. Mesocricetus auratus was chronically treated with intraperitoneal administration of the selective serotonin uptake inhibitor paroxetine or the gamma aminobutyric acid (GABA)/benzodiazepine receptor agonist alprazolam at three different doses and were then confronted with a venomous coral snake (Micrurus frontalis, Reptilia, Colubridae). The threatened rodents exhibited defensive attention, flat back approaches, defensive immobility, and escape defensive responses in the presence of the venomous snake, followed by increases in Fos protein in limbic structure neurons. Chronic administration of both paroxetine and alprazolam decreased these responses with morphological correlates between the panicolytic effect of both drugs administered at the highest dose and decreases in Fos protein-immunolabeled perikarya found in the amygdaloid complex, hypothalamus and periaqueductal gray matter columns, which are structures that make up the encephalic aversion system. These findings provide face, construct and predictive validities of this new experimental model of anxiety- and panic attack-like behavioral responses displayed by threatened prey confronted with venomous coral snakes.
Camera trapping is widely used in ecological studies. It is often considered nonintrusive simply because animals are not captured or handled. However, the emission of light and sound from camera traps can be intrusive. We evaluated the daytime and nighttime behavioral responses of four mammalian predators to camera traps in road-based, passive (no bait) surveys, in order to determine how this might affect ecological investigations. Wild dogs, European red foxes, feral cats, and spotted-tailed quolls all exhibited behaviors indicating they noticed camera traps. Their recognition of camera traps was more likely when animals were approaching the device than if they were walking away from it. Some individuals of each species retreated from camera traps and some moved toward them, with negative behaviors slightly more common during the daytime. There was no consistent response to camera traps within species; both attraction and repulsion were observed. Camera trapping is clearly an intrusive sampling method for some individuals of some species. This may limit the utility of conclusions about animal behavior obtained from camera trapping. Similarly, it is possible that behavioral responses to camera traps could affect detection probabilities, introducing as yet unmeasured biases into camera trapping abundance surveys. These effects demand consideration when utilizing camera traps in ecological research and will ideally prompt further work to quantify associated biases in detection probabilities.
* * * The herpetofauna of British Honduras is well known. Several recent papers (summarized by Neill, 1965), and the pioneer review by Schmidt (1941), provide a substantial species list and data on distribution and variation of many common species. As Schmidt (1941: 480) noted, "The faunal importance of British Honduras as an independent geographic area is slight, but a knowledge of its fauna is essential to the larger problem offered by that of the Yucatan Peninsula as a whole and to the delimitation of the endemic fauna of the northern part." Such faunal delimitation has been hindered by the lack of extensive collections from representative localities in British Honduras, since all records of British Honduras snakes are based on specimens from scattered localities. During the years 1964 through 1967 Eduardo C. Welling M. obtained a collection of 232 snakes at Middlesex, Stann Creek District, British Honduras. Among the 24 species represented are several previously reported only once or twice from British Honduras, and one addition to the species list (Amastridium veliferum). More important, it is the first quantitative sample of a local snake fauna from British Honduras. This collection is in the University of Colorado
This species, usually an inhabitant of tropical forest floor litter, was abundant under logs in a pasture. Stomachs contained earth-worms, slugs and snails. Eggs, hatchlings and a peculiar defensive head display are described
The role of secretions of sternal scent glands in social recognition was examined in captive adult female Virginia opossums, Didelphis virginiana. Five of six females directed significantly more investigative behavior toward plastic disks artificially scent marked with sternal odors from male conspecifics than toward those marked with sternal odors from females when odors were presented in paired male-female combinations. None investigated female odors more than those of males. Estrous status did not appear to influence responses to sternal odors. Subjects also demonstrated the ability to discriminate between individual odors of females presented in pairs, even though females lack the specialized sternal glands characteristic of males. No evidence was found for an ability of female opossums to discriminate among odors of individual males.