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Alves-Nunes JM, Fellone A, Almeida-Santos SM, de Medeiros CR, Sazima I, Vuolo Marques OA. Study of defensive behavior of a venomous snake as a new approach to understand snakebite. Sci Rep 2024; 14:10230. [PMID: 38702318 PMCID: PMC11068791 DOI: 10.1038/s41598-024-59416-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 04/10/2024] [Indexed: 05/06/2024] Open
Abstract
Snakebites affect millions of people worldwide. The majority of research and management about snakebites focus on venom and antivenom, with less attention given to snake ecology. The fundamental factor in snakebites is the snakes' defensive biting behavior. Herein we examine the effects of environmental variables (temperature, time of day, and human stimulus) and biological variables (sex and body size) on the biting behavior of a medically significant pit viper species in Brazil, Bothrops jararaca (Viperidae), and associate it with the epidemiology of snakebites. Through experimental simulations of encounters between humans and snakes, we obtained behavioral models applicable to epidemiological situations in the State of São Paulo, Brazil. We found a significant overlap between behavioral, morphological, environmental, and epidemiological data. Variables that increase snakebites in epidemiological data also enhance the tendency of snakes to bite defensively, resulting in snakebites. We propose that snakebite incidents are influenced by environmental and morphological factors, affecting the behavior of snakes and the proportion of incidents. Thus, investigating behavior of snakes related to snakebite incidents is a valuable tool for a better understanding of the epidemiology of these events, helping the prediction and, thus, prevention of snakebites.
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Affiliation(s)
- João Miguel Alves-Nunes
- Programa de Pós-Graduação em Biodiversidade, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, São Paulo, Brazil.
- Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil.
| | - Adriano Fellone
- Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil
- Programa de Pós- Graduação em Ecologia e Evolução, Universidade Federal de São Paulo, Campus Diadema, São Paulo, Brazil
| | - Selma Maria Almeida-Santos
- Programa de Pós-Graduação em Biodiversidade, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, São Paulo, Brazil
- Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil
| | | | - Ivan Sazima
- Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil
- Museu de Biodiversidade Biológica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Otavio Augusto Vuolo Marques
- Programa de Pós-Graduação em Biodiversidade, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, São Paulo, Brazil
- Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, São Paulo, Brazil
- Programa de Pós- Graduação em Ecologia e Evolução, Universidade Federal de São Paulo, Campus Diadema, São Paulo, Brazil
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Starostová Z, Píchová V, Bauerová A, Kubička L, Kratochvíl L. Catch-up growth and overweight adults in the offspring of young gecko mothers resembling low birth weight infants. Biol Lett 2024; 20:20230452. [PMID: 38228187 PMCID: PMC10791515 DOI: 10.1098/rsbl.2023.0452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 12/13/2023] [Indexed: 01/18/2024] Open
Abstract
Endothermic and ectothermic amniotes differ in the timing of reproductive onset, with reptiles initiating reproduction before reaching final body size. Long-term consequences of maternal effect for early reptile offspring are poorly explored. We conducted growth experiments to compare the growth of offspring produced by young and older females of gecko Paroedura picta. Young, not fully grown females lay smaller eggs leading to production of smaller offspring. These offspring undergo accelerated growth and ultimately reach a comparable sex-specific final body length as do offspring of older females. Final body length is thus canalized with respect to the maternal effect on egg size. Notably, the offspring of young mothers have a tendency towards larger body mass. Ontogeny of the offspring of young females shares similarities with that of mammalian offspring with low birth weight or early malnutrition, exhibiting catch-up growth and a predisposition to obesity. We highlight the important consequences of early reproduction for offspring in animals that initiate reproduction prior to reaching final body size. Both life-history models and conservation practices should take into account that female lizards might produce the most fit offspring only between reaching their final body length and the onset of reproductive senescence.
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Affiliation(s)
- Zuzana Starostová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
| | - Veronika Píchová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
| | - Anna Bauerová
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
| | - Lukáš Kubička
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
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Zamora-Camacho FJ. Keep the ball rolling: sexual differences in conglobation behavior of a terrestrial isopod under different degrees of perceived predation pressure. PeerJ 2023; 11:e16696. [PMID: 38144184 PMCID: PMC10740659 DOI: 10.7717/peerj.16696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/28/2023] [Indexed: 12/26/2023] Open
Abstract
Background Antipredator behaviors are theoretically subjected to a balance by which their display should be minimized when their benefits do not outweigh their costs. Such costs may be not only energetic, but also entail a reduction in the time available for other fitness-enhancing behaviors. However, these behaviors are only beneficial under predation risk. Therefore, antipredator behaviors are predicted to be maximized under strong predation risk. Moreover, predation pressure can differ among individuals according to traits such as sex or body size, if these traits increase vulnerability. Antipredator behaviors are expected to be maximized in individuals whose traits make them more conspicuous to predators. However, how sex, body size and antipredator behaviors interact is not always understood. Methods In this work, I tested the interaction between sex, body size and antipredator behavior in the common pill woodlouse (Armadillidium vulgare), which conglobate (i.e., they roll up their bodies almost conforming a sphere that conceals their appendages) in response to predator attacks. Specifically, I tested whether latency to unroll after a standardized mechanical induction was greater in animals exposed to predator chemical cues (toad feces) than in conspecifics exposed to cues of non-predatory animals (rabbits) or no chemical cues whatsoever (distilled water), incorporating sex and body mass in the analyses. Results In agreement with my prediction, latency to unroll was greater in individuals exposed to predator chemical cues. In other words, these animals engage in conglobation for longer under perceived predator vicinity. However, this result was only true for males. This sexual dimorphism in antipredator behavior could result from males being under greater predation risk than females, thus having evolved more refined antipredator strategies. Indeed, males of this species are known to actively search for females, which makes them more prone to superficial ground mobility, and likely to being detected by predators. Body size was unrelated to latency to unroll. As a whole, these results support the hypothesis that antipredator behavior is tuned to predator cues in a way consistent with a balance between costs and benefits, which might differ between the sexes.
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Denny KL, Huskey S, Anderson CV, Smith ME. Communication via Biotremors in the Veiled Chameleon (Chamaeleo calyptratus): Part I- Biotremor Production and Response to Substrate-Borne Vibrations. Integr Comp Biol 2023; 63:484-497. [PMID: 37365691 DOI: 10.1093/icb/icad085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/26/2023] [Accepted: 06/11/2023] [Indexed: 06/28/2023] Open
Abstract
Biotremors are vibrations, usually surface waves along the boundary of a medium, produced by an organism. While substrate-borne vibrations are utilized by different reptile species, true conspecific communication via biotremors has not yet been demonstrated in lizards. Recent research revealed that the veiled chameleon (Chamaeleo calyptratus) produces biotremors. The prerequisites for any communication system are the ability of an organism to produce and detect a signal. We tested C. calyptratus behavioral responses to vibrations by placing them on a dowel attached to a shaker, emitting vibrations of 25, 50, 150, 300, and 600 Hz and compared their locomotory velocity before and after the stimulus. Adult chameleons exhibited a freeze response to 50 and 150 Hz, while juveniles exhibited a similar response to frequencies between 50 and 300 Hz. In a second experiment, chameleons were induced to produce biotremors via experimenter contact. These biotremors ranged in mean fundamental frequency from 106.4 to 170.3 Hz and in duration from 0.06 to 0.29 s. Overall, two classes of biotremors were identified, "hoots" and "mini-hoots," which differed significantly in mean relative signal intensity (-7.5 and -32.5 dB, respectively). Juvenile chameleons 2 months of age were able to produce biotremors, suggesting this behavior may serve a wide range of ecological functions throughout ontogeny. Overall, the data demonstrate that C. calyptratus can both produce and detect biotremors that could be used for intraspecific communication.
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Affiliation(s)
- Kathryn L Denny
- Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA
| | - Steve Huskey
- Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA
| | | | - Michael E Smith
- Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA
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Niwa S, Osada N, Saeki I. Young climbers successfully avoid predators: survival behavioural strategy of juveniles of the land snail Ezohelix gainesi. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Abstract
Predation risk has a great influence on animal behaviour. Juveniles are often more susceptible to predation than adults owing to their small body size and limited locomotive ability. Ezohelix gainesi (Camaenidae) is a ground-dwelling land snail that swings its shell as a strategy to avoid predation by beetles. This strategy, however, does not seem to work in juveniles, probably because of their small shell size. Instead, small individuals climb plants as an alternative strategy that is likely to avoid predation; to examine this, we initially made an experimental comparison of the rates of predation by beetles on land snails of different sizes. In these conditions, smaller snails were preyed upon more frequently than larger ones. Next, we compared the size distribution of snails on plants with those on the forest floor. Small snails occurred more frequently on plants than on the ground, and the shell diameter of land snails at 50% probability of occurring on plants was similar to that at 50% probability of predation. Climbing behaviour by small snails was also confirmed in the laboratory in the absence of predators. Therefore, plant-climbing by juvenile E. gainesi is probably an adaptive strategy to avoid predation by ground-dwelling beetles.
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Affiliation(s)
- Shigeru Niwa
- Wildlife Research Center , 3-3-7 Kotobashi, Sumida-ku, Tokyo 130-8606 , Japan
| | - Noriyuki Osada
- Laboratory of Plant Conservation Science, Faculty of Agriculture, Meijo University , Nagoya, Aichi 468-8502 , Japan
| | - Ikuyo Saeki
- Faculty of Life and Environmental Sciences, University of Tsukuba , 1-1-1 Tennodai, Tsukuba, Ibaraki 305 - 8571 , Japan
- Makino Herbarium, Tokyo Metropolitan University , 1-1 Minamiosawa, Hachioji, Tokyo 192 - 0364 , Japan
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Piao Y, Yao G, Jiang H, Huang S, Huang F, Tang Y, Liu Y, Chen Q. Do pit vipers assess their venom? Defensive tactics of Deinagkistrodon acutus shift with changed venom reserve. Toxicon 2021; 199:101-108. [PMID: 34107276 DOI: 10.1016/j.toxicon.2021.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
To maximize survival probability, animals must assess predation risks and adopt flexible defensive strategies based on specific conditions. Pit vipers utilize venom for predation and self-defense, and venom status significantly influences its effectiveness. Thus, pit vipers may evaluate their venom reserve and adopt corresponding defensive tactics. Twenty-three sharp-snouted pit vipers (Deinagkistrodon acutus) were grouped by different venom status and were subjected to eight behavior trials. Subjects' defensive behaviors were recorded and analyzed. Results showed that the normal venom group displayed stable responses across the trials. The low venom group showed fewer strikes and more fleeing behaviors at the end of experiments. After given prolonged intervals for replenishing the venom, significant increases of strike behaviors were observed in the replenishing venom group. These results demonstrated the capability of adopting flexible defensive tactics based on varied venom reserve and provided new evidence for venom-status-recognition.
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Affiliation(s)
- Yige Piao
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
| | - Ge Yao
- State Key Laboratory of NBC Protection for Civilian, Beijing, 102205, China.
| | - Hui Jiang
- State Key Laboratory of NBC Protection for Civilian, Beijing, 102205, China.
| | - Song Huang
- Anhui Normal University, Wuhu, 241000, Anhui, China; Huangshan Noah Biodiversity Institute, Huangshan, 245000, Anhui, China.
| | - Feng Huang
- Huangshan Institute of Snake, Huangshan, 245000, Anhui, China.
| | - Yezhong Tang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
| | - Yang Liu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
| | - Qin Chen
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
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Golubović A, Anđelković M, Tomović L, Arsovski D, Gvozdenović S, Šukalo G, Ajtić R, Bonnet X. Death‐feigning propensity varies within dice snake populations but not with sex or colour morph. J Zool (1987) 2021. [DOI: 10.1111/jzo.12882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Golubović
- Institute of Zoology Faculty of Biology University of Belgrade Belgrade Serbia
| | - M. Anđelković
- Institute for Biological Research “Siniša Stanković” National Institute of Republic of Serbia University of Belgrade Belgrade Serbia
| | - L. Tomović
- Institute of Zoology Faculty of Biology University of Belgrade Belgrade Serbia
| | - D. Arsovski
- Macedonian Ecological Society Skopje North Macedonia
| | | | - G. Šukalo
- Faculty of Natural Sciences and Mathematics University of Banja Luka Banja Luka Bosnia and Herzegovina
| | - R. Ajtić
- Natural History Museum in Belgrade Belgrade Serbia
| | - X. Bonnet
- Centre d'Etudes Biologiques de Chizé Villiers‐en‐Bois France
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8
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Cox CL, Chung AK, Blackwell C, Davis MM, Gulsby M, Islam H, Miller N, Lambert C, Lewis O, Rector IV, Walsh M, Yamamoto AD, Davis Rabosky AR. Tactile stimuli induce deimatic antipredator displays in ringneck snakes. Ethology 2021. [DOI: 10.1111/eth.13152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Christian L. Cox
- Department of Biological Sciences Florida International University Miami FL USA
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Albert K. Chung
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
- Department of Ecology and Evolutionary Biology University of California Los Angeles Los Angeles CA USA
| | | | - Maura M. Davis
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Miranda Gulsby
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
- Department of Biology Kennesaw State University Kennesaw GA USA
| | - Hasib Islam
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Nathan Miller
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
- James Madison University Harrisonburg VA USA
| | - Carson Lambert
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Olivia Lewis
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Ian V. Rector
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Marleigh Walsh
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Alannah D. Yamamoto
- Mountain Lake Biological Station University of Virginia Charlottesville VA USA
- University of Maryland College Park MD USA
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Allf BC, Sparkman AM, Pfennig DW. Microevolutionary change in mimicry? Potential erosion of rattling behaviour among nonvenomous snakes on islands lacking rattlesnakes. ETHOL ECOL EVOL 2021. [DOI: 10.1080/03949370.2020.1837962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Bradley C. Allf
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA
| | | | - David W. Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
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Davis Rabosky AR, Moore TY, Sánchez-Paredes CM, Westeen EP, Larson JG, Sealey BA, Balinski BA. Convergence and divergence in anti-predator displays: a novel approach to quantitative behavioural comparison in snakes. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blaa222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abstract
Animals in nature use many strategies to evade or deter their predators. Within venomous snake mimicry, stereotyped anti-predator behaviours are hypothesized to be effective warning signals under strong selection for independent convergence across species. However, no studies have systematically quantified snake anti-predator displays across taxonomically broad clades to examine how these behaviours evolve within a comparative methods framework. Here we describe a new high-throughput approach for collecting and quantifying anti-predator displays in snakes that demonstrates both low observer bias and infinite extension. Then, we show this method’s utility by comparing 20 species spanning six taxonomic families from Peru. We found that a simple experimental set-up varying simulated predator cues was successful in eliciting displays across species and that high-speed videography captured a great diversity of anti-predator responses. Although display components show complicated patterns of covariance, we found support for behavioural convergence in anti-predator displays among elapid coral snakes and their distantly related mimics. Our approach provides new analytical opportunities for both behaviour and kinematics, especially macroevolutionary analyses across clades with similar difficulty in observing or comparing trait diversity.
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Affiliation(s)
- Alison R Davis Rabosky
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
| | - Talia Y Moore
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
- Department of Mechanical Engineering and Robotics Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Ciara M Sánchez-Paredes
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
- Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Department of Environment and Geography, University of York, Heslington, York, UK
| | - Erin P Westeen
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
- Department of Environmental Science, Policy, and Management and Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
| | - Joanna G Larson
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Briana A Sealey
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
| | - Bailey A Balinski
- Department of Ecology and Evolutionary Biology and Museum of Zoology (UMMZ), University of Michigan, Ann Arbor, Michigan, USA
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Meter B, Starostová Z, Kubička L, Kratochvíl L. The limits of the energetical perspective: life-history decisions in lizard growth. Evol Ecol 2020. [DOI: 10.1007/s10682-020-10054-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Lopes de Assis C, José Magalhães Guedes J, Miriam Gomes de Jesus L, Neves Feio R. New defensive behaviour of the false coral snake Oxyrhopus rhombifer Duméril, Bibron & Duméril, 1854 (Serpentes, Dipsadidae) in south-eastern Brazil. NEOTROPICAL BIOLOGY AND CONSERVATION 2020. [DOI: 10.3897/neotropical.15.e48564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Anti-predator mechanisms are essential for species survival and the description of defensive behaviour may improve our understanding about the ecology, biology and evolution of species. Herein, we describe new anti-predator behaviour for the False Coral Snake Oxyrhopus rhombifer in south-eastern Brazil, through direct observation of a juvenile specimen under laboratory settings. We recorded 10 types of defensive behaviour, seven of which are new records for this species and one of them (body vibration) is the first report for Brazilian snakes. Such behaviour may be explained by ontogeny or physical constraints. We highlight that O. rhombifer may be capable of recognising different threat levels imposed by predators and, accordingly, adjusting its defensive behaviour.
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13
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Angarita-Sierra T, Montañez-Méndez A, Toro-Sánchez T, Rodríguez-Vargas A. A case of envenomation by the false fer-de-lance snake Leptodeira annulata (Linnaeus, 1758) in the department of La Guajira, Colombia. BIOMEDICA : REVISTA DEL INSTITUTO NACIONAL DE SALUD 2020; 40:20-26. [PMID: 32220160 PMCID: PMC7357383 DOI: 10.7705/biomedica.4773] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 08/05/2019] [Indexed: 11/30/2022]
Abstract
Envenomations by colubrid snakes in Colombia are poorly known, consequently, the clinical relevance of these species in snakebite accidents has been historically underestimated. Herein, we report the first case of envenomation by opisthoglyphous snakes in Colombia occurred under fieldwork conditions at the municipality of Distracción, in the department of La Guajira. A female biologist was bitten on the index finger knuckle of her right hand when she tried to handle a false fer-de-lance snake (Leptodeira annulata). Ten minutes after the snakebite, the patient started to have symptoms of mild local envenomation such as edema, itching, and pain in the wound. After 40 minutes, the edema reached its maximum extension covering the dorsal surface of the right hand and causing complete loss of mobility. The clinical treatment focused on pain and swelling control. No laboratory tests were performed. The patient showed good progress with the total regression of the edema 120 hours after the snake-bite accident and complete recovery of the movement of the limb in one week. Venomous bites of "non-venomous snakes" (opisthoglyphous colubrid snakes) must be considered as a significant public health problem because patients lose their work capability during hours or even days and they are forced to seek medical assistance to treat the envenomation manifestations.
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Affiliation(s)
- Teddy Angarita-Sierra
- Vicerrectoría de Investigación, Universidad Manuela Beltrán, Bogotá, D.C., Colombia; Yoluka ONG, Fundación de Investigación en Biodiversidad y Conservación, Bogotá, D.C., Colombia.
| | | | - Tatiana Toro-Sánchez
- Yoluka ONG, Fundación de Investigación en Biodiversidad y Conservación, Bogotá, D.C., Colombia.
| | - Ariadna Rodríguez-Vargas
- Grupo de Investigación en Proteínas, Departamento de Química, Universidad Nacional de Colombia, Bogotá, D.C., Colombia.
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Kurali A, Pásztor K, Hettyey A, Tóth Z. Resource-dependent temporal changes in antipredator behavior of common toad (Bufo bufo) tadpoles. Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2503-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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15
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Kowalski K, Sawościanik O, Rychlik L. Do Bufonids Employ Different Anti-Predator Behaviors Than Ranids? Comparison among Three European Anurans. COPEIA 2018. [DOI: 10.1643/ce-16-567] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Herr MW, Graham SP, Langkilde T. Stressed snakes strike first: Hormone levels and defensive behavior in free ranging cottonmouths (Agkistrodon piscivorus). Gen Comp Endocrinol 2017; 243:89-95. [PMID: 27823955 DOI: 10.1016/j.ygcen.2016.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/29/2016] [Accepted: 11/03/2016] [Indexed: 01/02/2023]
Abstract
Stress is believed to be an important factor mediating animal behavior. Here we explore the relationship between concentrations of a stress hormone and defensive behavior of a snake. The cottonmouth (Agkistrodon piscivorus) is an abundant, large-bodied pitviper that is well known for its intense defensive behaviors. The defensive behaviors and hormonal ecology of cottonmouths have been studied extensively, but the interaction between these is not well understood. We conducted field trials, recording the snake's behavior and obtaining blood samples to quantify plasma CORT concentrations, both upon first encountering a snake and after a 30min standardized confinement stressor. We found that snakes with elevated levels of baseline CORT at first encounter were more likely to strike than exhibit a threat display when approached in the field. However, this behavior was not related to the magnitude of the snake's CORT increase following confinement, suggesting that more stress-prone snakes are not more defensive. Post-stressor antipredator behavior was also not related to any of our CORT measures. This study suggests that baseline CORT levels can be important correlates of defensive behavior. If this is a causative relationship, environmental challenges that increase baseline stress levels of populations may elevate cottonmouth defensive behavior. This would increase costs associated with defensive behavior (energetic, lost opportunity, etc.) and have important consequences for animal-human interactions.
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Affiliation(s)
- Mark W Herr
- Department of Biology, The Pennsylvania State University, USA.
| | - Sean P Graham
- Department of Biology, Geology, and Physical Sciences, Sul Ross State University, USA
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, USA; Intercollege Graduate Degree Program in Ecology, and The Center for Brain, Behavior and Cognition, The Pennsylvania State University, USA
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Visser F, Curé C, Kvadsheim PH, Lam FPA, Tyack PL, Miller PJO. Disturbance-specific social responses in long-finned pilot whales, Globicephala melas. Sci Rep 2016; 6:28641. [PMID: 27353529 PMCID: PMC4926103 DOI: 10.1038/srep28641] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 06/07/2016] [Indexed: 11/29/2022] Open
Abstract
Social interactions among animals can influence their response to disturbance. We investigated responses of long-finned pilot whales to killer whale sound playbacks and two anthropogenic sources of disturbance: tagging effort and naval sonar exposure. The acoustic scene and diving behaviour of tagged individuals were recorded along with the social behaviour of their groups. All three disturbance types resulted in larger group sizes, increasing social cohesion during disturbance. However, the nature and magnitude of other responses differed between disturbance types. Tagging effort resulted in a clear increase in synchrony and a tendency to reduce surface logging and to become silent (21% of cases), whereas pilot whales increased surface resting during sonar exposure. Killer whale sounds elicited increased calling rates and the aggregation of multiple groups, which approached the sound source together. This behaviour appears to represent a mobbing response, a likely adaptive social defence against predators or competitors. All observed response-tactics would reduce risk of loss of group coordination, suggesting that, in social pilot whales, this could drive behavioural responses to disturbance. However, the behavioural means used to achieve social coordination depends upon other considerations, which are disturbance-specific.
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Affiliation(s)
- Fleur Visser
- Kelp Marine Research, Loniusstraat 9, 1624 CJ, Hoorn, The Netherlands
- Behavioural Biology Group, Leiden University, PO Box 9505, Leiden, 2300 RA, The Netherlands
| | - Charlotte Curé
- CEREMA–DTer Est, Acoustics Group, F-67035, Strasbourg Cedex 2, France
| | - Petter H. Kvadsheim
- Norwegian Defence Research Establishment FFI, Maritime Systems Division, NO-3191, Horten, Norway
| | - Frans-Peter A. Lam
- Acoustics and Sonar, TNO, PO Box 96864, The Hague, 2509 JG, The Netherlands
| | - Peter L. Tyack
- Sea Mammal Research Unit, University of St. Andrews, St. Andrews, Fife, KY16 8LB, UK
| | - Patrick J. O. Miller
- Sea Mammal Research Unit, University of St. Andrews, St. Andrews, Fife, KY16 8LB, UK
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18
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Siers SR, Reed RN, Savidge JA. To cross or not to cross: modeling wildlife road crossings as a binary response variable with contextual predictors. Ecosphere 2016. [DOI: 10.1002/ecs2.1292] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Shane R. Siers
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado 80523 USA
| | - Robert N. Reed
- U.S. Geological Survey Fort Collins Science Center Fort Collins Colorado 80526 USA
| | - Julie A. Savidge
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado 80523 USA
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Suchomelová P, Jančúchová-Lásková J, Landová E, Frynta D. Experimental assessment of social interactions in two species of the genus Teratoscincus (Gekkota). Behav Processes 2015; 120:14-24. [PMID: 26299547 DOI: 10.1016/j.beproc.2015.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 11/29/2022]
Abstract
Social organization of many reptile species that are rare in the wild remains rather unexplored due to difficulties when setting experiments in the field. Behavioral analysis of standard social situations in laboratory conditions is considered an indirect method to reveal social behavior in the field. We studied two rare species of geckos, Teratoscincus scincus and Teratoscincus keyserlingii, inhabiting sand dunes of Uzbekistan and Eastern Iran. A series of experiments was carried out to quantify responses in social interactions among conspecific adults as well as reactions of these towards conspecific/heterospecific subadults and juveniles. We also assessed the effect of species and sex on recorded behavior. Finally, the reaction to threat stimuli simulating predator attack was analyzed. The species effect was recorded only in the response to a simulated predatory attack: T. scincus typically escaped whereas larger T. keyserlingii attacked the stimulus. In accordance with the sexual competition hypothesis, agonistic interactions were nearly exclusively confined to male-male encounters while females were tolerant to each other. Male-female encounters regularly resulted in mating attempts, which suggests that females are not strongly selective in choosing partners. Therefore, male aggression can be linked to mate guarding or territoriality. Adults' lack of interest in immature geckos may indicate generalized tolerance of adults towards young.
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Affiliation(s)
- Petra Suchomelová
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague, Czech Republic.
| | - Jitka Jančúchová-Lásková
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague, Czech Republic.
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague, Czech Republic.
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague, Czech Republic.
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21
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Hoss SK, Clark RW. Mother Cottonmouths (Agkistrodon piscivorus) Alter Their Antipredator Behavior in the Presence of Neonates. Ethology 2014. [DOI: 10.1111/eth.12265] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shannon K. Hoss
- Department of Biology; San Diego State University; San Diego CA USA
| | - Rulon W. Clark
- Department of Biology; San Diego State University; San Diego CA USA
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22
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Ontogenetic switch between alternative antipredatory strategies in the leopard gecko (Eublepharis macularius): defensive threat versus escape. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1536-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Citadini JM, Navas CA. Inter-individual variation and temperature-dependent antipredator behavior in the snake Tomodon dorsatus (Dipsadidae). Behav Processes 2013; 97:11-7. [PMID: 23548560 DOI: 10.1016/j.beproc.2013.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/14/2013] [Indexed: 11/17/2022]
Abstract
Although many studies assessed the influence of temperature on the behavior of ectotermic vertebrates, little attention has been given to interindividual variation in the defensive responses of reptiles. In the present study we investigated the defensive behavior of the snake Tomodon dorsatus, in order to test the hypotheses that (1) individuals differ in their antipredator behavior consistently with the concept of behavioral syndromes, (2) temperature influences the defensive behavior, and (3) these two factors interact with each other. There was significant interindividual variation in defensive behavior, as well as consistently aggressive, passive or evasive behaviors. Temperature influenced aggressiveness, which was slightly higher when body temperature was lower, but this trend was only evident in animals with aggressive disposition. Our results corroborate the hypothesis of interaction between individuality of behavior and temperature-dependent defensive behavior in T. dorsatus. These results, together with results from previous studies, suggest that the evolution of temperature-dependent defensive behavior differs among lineages of ectothermic tetrapods. This article is part of a Special Issue entitled: insert SI title.
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Affiliation(s)
- Jessyca Michele Citadini
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Trav. 14, n° 321, Cidade Universitária, CEP: 05508-090 São Paulo, SP, Brazil
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24
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May PG, Farrell TM. Growth Patterns of Dusky Pygmy Rattlesnakes (Sistrurus miliarius barbouri) from Central Florida. HERPETOLOGICAL MONOGRAPHS 2012. [DOI: 10.1655/herpmonographs-d-11-00003.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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25
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Young aphids avoid erroneous dropping when evading mammalian herbivores by combining input from two sensory modalities. PLoS One 2012; 7:e32706. [PMID: 22496734 PMCID: PMC3322135 DOI: 10.1371/journal.pone.0032706] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 02/02/2012] [Indexed: 11/19/2022] Open
Abstract
Mammalian herbivores may incidentally ingest plant-dwelling insects while foraging. Adult pea aphids (Acyrthosiphon pisum) avoid this danger by dropping off their host plant after sensing the herbivore's warm and humid breath and the vibrations it causes while feeding. Aphid nymphs may also drop (to escape insect enemies), but because of their slow movement, have a lower chance of finding a new plant. We compared dropping rates of first-instar nymphs with those of adults, after exposing pea aphids to different combinations of simulated mammalian breath and vibrations. We hypothesized that nymphs would compensate for the greater risk they face on the ground by interpreting more conservatively the mammalian herbivore cues they perceive. Most adults dropped in response to breath alone, but nymphs rarely did so. Breath stimulus accompanied by one concurrent vibrational stimulus, caused a minor rise in adult dropping rates. Adding a second vibration during breath had no additional effect on adults. The nymphs, however, relied on a combination of the two types of stimuli, with a threefold increase in dropping rates when the breath was accompanied by one vibration, and a further doubling of dropping rates when the second vibration was added. The age-specificity of the aphids' herbivore detection mechanism is probably an adaptation to the different cost of dropping for the different age groups. Relying on a combination of stimuli from two sensory modalities enables the vulnerable nymphs to avoid costly mistakes. Our findings emphasize the importance of the direct trophic effect of mammalian herbivory for plant-dwelling insects.
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Sperry JH, Weatherhead PJ. Individual and sex‐based differences in behaviour and ecology of rat snakes in winter. J Zool (1987) 2012. [DOI: 10.1111/j.1469-7998.2011.00895.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. H. Sperry
- Program in Ecology Evolution and Conservation Biology University of Illinois Champaign IL USA
- Engineer Research and Development Center Champaign IL USA
| | - P. J. Weatherhead
- Program in Ecology Evolution and Conservation Biology University of Illinois Champaign IL USA
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Nowak EM, Theimer TC, Schuett GW. Functional and Numerical Responses of Predators: Where Do Vipers Fit in the Traditional Paradigms? Biol Rev Camb Philos Soc 2008; 83:601-20. [DOI: 10.1111/j.1469-185x.2008.00056.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Oswald M, Robison BD. Strain-specific alteration of zebrafish feeding behavior in response to aversive stimuli. CAN J ZOOL 2008; 86:1085-1094. [PMID: 21379405 DOI: 10.1139/z08-085] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Behavioral management of risk, in which organisms must balance the requirements of obtaining food resources with the risk of predation, has been of considerable interest to ethologists for many years. Although numerous experiments have shown that animals alter their foraging behavior depending on the levels of perceived risk and demand for nutrients, few have considered the role of genetic variation in the trade-off between these variables. We performed a study of four zebrafish (Danio rerio (Hamilton, 1822)) strains to test for genetic variation in foraging behavior and whether this variation affected their response to both aversive stimuli and nutrient restriction. Zebrafish strains differed significantly in their latency to begin foraging from the surface of the water under standard laboratory conditions. Fish fed sooner when nutrients were restricted, although this was only significant in the absence of aversive stimuli. Aversive stimuli caused fish to delay feeding in a strain-specific manner. Strains varied in food intake and specific growth rate, and feeding latency was significantly correlated with food intake. Our results indicate significant genetic variation in foraging behavior and the perception of risk in zebrafish, with a pattern of strain variation consistent with behavioral adaptation to captivity.
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Affiliation(s)
- M Oswald
- University of Idaho, Department of Biological Sciences, P.O. Box 443051, Moscow, ID 83844-3051, USA
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29
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Dangles O, Pierre D, Christides JP, Casas J. Escape performance decreases during ontogeny in wild crickets. ACTA ACUST UNITED AC 2007; 210:3165-70. [PMID: 17766293 DOI: 10.1242/jeb.004648] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Increasing the ecological relevance of studies relating to the performance of organisms has been a central issue for functional biologists over the last few years. Of particular concern are changes in performance throughout the life cycle as selective forces act differently on various life stages. We addressed this issue experimentally by following ontogenic variations in the escape performance of crickets threatened by artificial predatory signals. We measured their performance under natural settings, which is a necessary approach yet one that is undocumented in insects. We analysed numeric film sequences obtained using a high-speed video camera at 1000 frames s(-1) to quantify wild cricket performance and behaviour in the field. We detected significant differences in cricket escape performance throughout ontogeny. Escape performances were higher in juvenile crickets than older instars. Complementary behavioural measurements for escaping crickets suggest that these variations may be related to the lower predatory risk perceived by large adults than by juveniles. We expect that our analysis of size-refuge will also improve our understanding in the development of performance, given its importance in community and population ecology theories.
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Affiliation(s)
- O Dangles
- Université de Tours, IRBI UMR CNRS 6035, Parc Grandmont, 37200 Tours, France.
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30
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Glaudas X, Winne CT. Do warning displays predict striking behavior in a viperid snake, the cottonmouth (Agkistrodon piscivorus)? CAN J ZOOL 2007. [DOI: 10.1139/z07-025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Warning displays are defined as signals designed to intimidate predators or indicate a proclivity to fight. However, support for the idea that warning behaviors signal an intent to fight is largely based on anecdotes and isolated observations, and a complete understanding of antipredator behavior will only be achieved if specific hypotheses are experimentally tested. Herein, we tested in a North American viperid snake, the cottonmouth ( Agkistrodon piscivorus (Lacépède, 1789)), the hypothesis that warning displays serve as a reliable signal to potential predators that a snake will strike. The cottonmouth exhibits two stereotypical warning displays during predator confrontation, i.e., mouth gaping and tail vibrations, making it an ideal study organism to experimentally test the relationship between warning displays and defensive striking. To test this idea, we recorded the sequence of defensive behavior — gaping, tail vibrating, and striking — of cottonmouths towards a standardized predatory stimulus in the laboratory. As predicted, snakes that gaped during the trials were subsequently more likely to strike than snakes that did not. In contrast, striking behavior was independent of the occurrence of tail vibrations. Our results suggest that gaping behavior — but not tail-vibrating behavior — may provide an honest signal to would-be predators.
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Affiliation(s)
- Xavier Glaudas
- University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
| | - Christopher T. Winne
- University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
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31
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Reaney LT. Foraging and mating opportunities influence refuge use in the fiddler crab, Uca mjoebergi. Anim Behav 2007. [DOI: 10.1016/j.anbehav.2006.05.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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32
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Glaudas X, Winne CT, Fedewa LA. Ontogeny of Anti-Predator Behavioral Habituation in Cottonmouths (Agkistrodon piscivorus). Ethology 2006. [DOI: 10.1111/j.1439-0310.2005.01183.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Loehr J, Kovanen M, Carey J, Högmander H, Jurasz C, Kärkkäinen S, Suhonen J, Ylönen H. Gender- and age-class-specific reactions to human disturbance in a sexually dimorphic ungulate. CAN J ZOOL 2005. [DOI: 10.1139/z05-162] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
According to optimality theory, an individual's characteristics should play a major part in determining antipredator strategies. We studied behavioural reactions to human presence of gender and age classes of 35 thinhorn sheep (Ovis dalli Nelson, 1884) in late winter 2001 in Faro, Yukon Territory, Canada. The behaviour of undisturbed sheep was observed from distances of 400–1200 m and compared with the behaviour recorded when one or two people were in close proximity to the sheep. Ewes decreased bedding and increased foraging when humans were present, but there were no changes in these behaviours in rams. Disturbance caused an increase in vigilance and a trend was found for adults to react more strongly to disturbance than juveniles. We demonstrate the importance for disturbance research of gaining detailed information about all different kinds of population members and using applicable statistical tests in the data analyses.
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Aubret F, Bonnet X. Influence of body reserves and eye opacity on foraging behaviours of tiger snakes. ACTA ACUST UNITED AC 2005; 303:1075-84. [PMID: 16254914 DOI: 10.1002/jez.a.229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Physiological states such as reproductive stage, parasite load, body condition, and environmental conditions, influence behaviours in complex ways. According to the Clark's asset-protection principle (Clark, 1994. Behav Ecol 5:159-170), individuals in good body condition take fewer predation risks than conspecifics in lesser condition. In many ectotherms, foraging, digestion, and moulting require an elevation of the metabolism achieved through intensive basking, thereby increasing the risk of being detected by predators. Using four experimental groups of snakes, we showed that two independent physiological states, (1) the presence of prey in the stomach and (2) eye opacity associated with moulting, increase predator vulnerability. In a parallel experiment, two groups of snakes were maintained on contrasting diets (high food intake vs. low food intake) for 6 months. Apart from sloughing periods, most individuals (89%) accepted their meal irrespective of food treatment. Consequently, well-fed snakes exhibited higher body condition (one third physiological state) relative to less-fed individuals. During sloughing events, however, well-fed individuals often refused (78%) to eat while the less-fed individuals readily accepted (86%) their meal despite eye opacity. Individuals with less body reserves accepted the cumulative risks owing to eye opacity and stomach fullness. By contrast, well-fed snakes remained more "prudent" (i.e., exhibited behaviours that depended on their internal state). Our results show that snakes can adjust their foraging "decision" by combining different physiological informations.
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