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Predator Avoidance (predator + avoidance)
Selected AbstractsSpatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio trackingAFRICAN JOURNAL OF ECOLOGY, Issue 3 2001Frauke Fischer Abstract Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex-specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics. Résumé On a étudié par radio-télémétrie l'utilisation spatiale et temporelle de l'habitat par les cobes (Kobus kob kob) au Parc National de Comoé (en Côte d'Ivoire, Afrique de l'Ouest). On a équipé un total de 23 cobes de colliers radio et on les a suivis pendant 15 mois (pour certains). L'espace vital des mâles était plus petit et celui des femelles plus grand que ce à quoi on s'attendait d'après les modèles théoriques. Les mâles adultes couvraient une zone plus réduite que les femelles adultes et ne déplaçaient pas leur espace vital en fonction des saisons. Les distances parcourues chaque jour étaient les mêmes pour les deux sexes. Les cobes se déplaçaient moins la nuit que le jour, et couvraient de plus courtes distances pendant la saison des pluies. Alors qu'une augmentation du recouvrement entre espaces vitaux des femelles aboutissait à un taux supérieur d'associations entre individus, l'association d'adultes des deux sexes n'était pas liée au taux de recouvrement des espaces vitaux. On suggère que le comportement territorial des mâles et l'évitement des prédateurs par les femelles pourraient expliquer les différences, spécifiques au sexe, de la dimension de l'espace vital des adultes et la déviation par rapport aux dimensions prévues. On suppose que l'évitement des prédateurs est la raison principale de la limitation des déplacements de nuit ainsi qu'en saison des pluies. On suppose que le comportement reproducteur et l'écologie alimentaire déterminent le degré d'association entre membres de la même espèce. [source] Food abundance affects both morphology and behaviour of juvenile perchECOLOGY OF FRESHWATER FISH, Issue 2 2008J. Borcherding Abstract,,, Behaviour and morphology were both shown to differ between 1+ perch from two lakes that in earlier studies showed differences in size-specific predation risk. As the level of nourishment is known to affect behaviour and morphology, we fed perch of the two lakes in tanks for 40 days with two food levels, to study whether observed differences remain stable with changes in food availability. The perch fed in excess grew significantly, while the perch at the low food conditions lost weight, clearly indicating undernourishment. In aquarium experiments, the starved perch from both lakes were much bolder in the trade-off between foraging and predator avoidance than their well-fed conspecifics. In addition, the shape of perch differed significantly between feeding treatments. At low food levels perch got a more slender body, while at high food levels they developed a deeper body and a relatively smaller head. Independent of feeding level, the comparison between the two lakes revealed a clearly deeper body and a larger head area for one population, a shape difference that remained stable after the feeding period. The results give evidence that the level of nourishment is an important factor that quickly alters risk-taking behaviour. In body morphology, however, more stable shape characteristics must be distinguished from more flexible ones. Consequently, the level of nourishment is a potential factor that may quickly hide other proximate cues and must be considered attentively in studies, in which shape changes and behaviour are related to environmental factors like diet, predation pressure or habitat diversity. [source] Dissolved copper triggers cell death in the peripheral mechanosensory system of larval fishENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Tiffany L. Linbo Abstract Dissolved copper is an increasingly common non,point source contaminant in urban and urbanizing watersheds. In the present study, we investigated the sublethal effects of dissolved copper on the peripheral mechanosensory system, or lateral line, of larval zebrafish (Danio rerio). Zebrafish larvae were exposed to copper (0,65 ,g/L), and the cytotoxic responses of individual lateral line receptor neurons were examined using a combination of in vivo fluorescence imaging, confocal microscopy, scanning electron microscopy, and conventional histology. Dissolved copper triggered a dose-dependent loss of neurons in identified lateral line neuromasts at concentrations ,20 ,g/L. The onset of cell death in the larval mechanosensory system was rapid (<1 h). When copper-exposed zebrafish were transferred to clean water, the lateral line regenerated over the course of 2 d. In contrast, the lateral line of larvae exposed continuously to dissolved copper (50 ,g/L) for 3 d did not recover. Collectively, these results show that peripheral mechanosensory neurons are vulnerable to the neurotoxic effects of copper. Consequently, dissolved copper in non-point source storm-water runoff has the potential to interfere with rheotaxis, schooling, predator avoidance, and other mechanosensory-mediated behaviors that are important for the migration and survival of fish. [source] Eavesdropping on the Neighbourhood: Collared Pika (Ochotona collaris) Responses to Playback Calls of Conspecifics and HeterospecificsETHOLOGY, Issue 10 2009Sarah A. Trefry The acoustic environment, composed in part by the vocalizations of sympatric animals, is a major source of information and can be used to fine-tune behavioural decisions. Active assessment of alarm calls within and between mammal species is not fully understood. We explored the behavioural responses of collared pikas to con- and heterospecific vocalizations, in order to determine whether they selectively attend to these calls. Pikas increased their vigilance after playback of alarm calls of heterospecific mammals (marmots and ground squirrels), but responded most strongly to conspecific calls. While responses to playback calls of their own, of neighbours and of a stranger did not differ, pikas did discriminate between individual callers in a habituation-discrimination experiment. The ability to make use of information from different sources in their acoustic environment likely facilitates pikas' behavioural decisions that affect foraging, predator avoidance and nepotism. [source] Detection and Avoidance of Predators in White-Tailed Deer (Odocoileus virginianus) and Mule Deer (O. hemionus)ETHOLOGY, Issue 2 2001Susan Lingle In this paper, we investigate the relationship between early detection of predators and predator avoidance in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus), two closely related species that differ in their habitat preferences and in their anti-predator behavior. We used observations of coyotes (Canis latrans) hunting deer to test whether the distance at which white-tails and mule deer alerted to coyotes was related to their vulnerability to predation. Coyote encounters with both species were more likely to escalate when deer alerted at shorter distances. However, coyote encounters with mule deer progressed further than encounters with white-tails that alerted at the same distance, and this was not due to species differences in group size or habitat. We then conducted an experiment in which a person approached groups of deer to compare the detection abilities and the form of alert response for white-tails and mule deer, and for age groups within each species. Mule deer alerted to the approacher at longer distances than white-tails, even after controlling for variables that were potentially confounding. Adult females of both species alerted sooner than conspecific juveniles. Mule deer almost always looked directly at the approacher as their initial response, whereas white-tails were more likely to flee or to look in another direction with no indication that they pinpointed the approacher during the trial. Mule deer may have evolved the ability to detect predators earlier than white-tails as an adaptation to their more open habitats, or because they need more time to coordinate subsequent anti-predator defenses. [source] Confusion Effect in a Reptilian and a Primate PredatorETHOLOGY, Issue 8 2000Carsten Schradin The confusion effect is claimed to be one benefit of group living with respect to predator avoidance: it is more difficult for predators to capture prey that is surrounded by other conspecifics than to capture an isolated individual. So far, the predictions of the confusion effect have been tested mainly in aquatic predators. As the confusion effect is seen to be a general problem for predators, terrestrial predators of two different vertebrate classes were used to test it. The prey (mealworms and black beetles, Tenebrio molitor) was harmless and had no chance of predator avoidance. Thus, confounding effects of group defence and enhanced vigilance were controlled. Both leopard geckos (Eublepharis macularius) and common marmosets (Callithrix jacchus) took longer to catch one out of several prey compared to one single prey. Leopard geckos showed more fixations (changing of head position) when confronted with 20 mealworms than when confronted with only one mealworm, thus showing indications of being ,confused'. [source] Non-lethal predator effects on the performance of a native and an exotic crayfish speciesFRESHWATER BIOLOGY, Issue 12 2005PER NYSTRÖM Summary 1. I tested the hypothesis that the potential for non-lethal effects of predators are more important for overall performance of the fast-growing exotic signal crayfish (Pacifastacus leniusculus Dana) than for the slower growing native noble crayfish (Astacus astacus L.). I further tested if omnivorous crayfish switched to feed on less risky food sources in the presence of predators, a behaviour that could reduce the feeding costs associated with predator avoidance. 2. In a 2 month long outdoor pool experiment, I measured behaviour, survival, cheliped loss, growth, and food consumption in juvenile noble or signal crayfish in pools with either a caged predatory dragonfly larvae (Aeshna sp.), a planktivorous fish that do not feed on crayfish (sunbleak, Leucaspius delineatus Heckel), or predator-free controls. Crayfish had access to multiple food sources: live zooplankton, detritus and periphyton. Frozen chironomid larvae were also supplied ad libitum outside crayfish refuges, simulating food in a risky habitat. 3. Crayfish were mainly active during hours of darkness, with signal crayfish spending significantly more time outside refuges than noble crayfish. The proportion of crayfish outside refuges varied between crayfish species, time and predator treatment, with signal crayfish spending more time in refuges at night in the presence of fish. 4. Survival in noble crayfish was higher than in signal crayfish, and signal crayfish had a higher frequency of lost chelipeds, indicating a high level of intraspecific interactions. Crayfish survival was not affected by the presence of predators. 5. Gut-contents analysis and stable isotope values of carbon (,13C) and nitrogen (,15N) indicated that the two crayfish species had similar food preferences, and that crayfish received most of their energy from feeding on invertebrates (e.g. chironomid larvae), although detritus was the most frequent food item in their guts. Signal crayfish guts were more full than those of noble crayfish, but signal crayfish in pools with fish contained significantly less food and fewer had consumed chironomids compared with predator-free controls. Length increase of signal crayfish (35%) was significantly higher than of noble crayfish (20%), but signal crayfish in pools with fish grew less than in control pools. 6. This short-term study indicates that fish species that do not pose a lethal threat to an organism may indirectly cause reductions in growth by affecting behaviour and feeding. This may occur even though prey are omnivorous and have access to and consume multiple food sources. These non-lethal effects of predators are expected to be particularly important in exotic crayfish species that show a general response to fish, have high individual growth rates, and when their feeding on the most profitable food source is reduced. [source] Response of small rodents to manipulations of vegetation height in agro-ecosystemsINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 1 2008Jens JACOB Abstract Some small mammal populations require human interference to conserve rare or threatened species or to minimize adverse effects in plant production. Without a thorough understanding about how small rodents behave in their environment and consideration of how they react to management efforts, management will not be optimal. Social behavior, spatial and temporal activity patterns, predator avoidance and other behavioral responses can affect pest rodent management. Some of these behavioral patterns and their causes have been well studied. However, their impact on pest rodent management, especially for novel management approaches, is not always clear. Habitat manipulation occurs necessarily through land use and intentionally to reduce shelter and food availability and to increase predation pressure on rodents. Rodents often respond to decreased vegetation height with reduced movements and increased risk sensitivity in their feeding behavior. This seems to result mainly from an elevated perceived predation risk. Behavioral responses may lessen the efficacy of the management because the desired effects of predators might be mediated. It remains largely unknown to what extent such responses can compensate at the population level for the expected consequences of habitat manipulation and how population size and crop damage are affected. It is advantageous to understand how target and non-target species react to habitat manipulation to maximize the management effects by appropriate techniques, timing and spatial scale without causing unwanted effects at the system level. [source] Spatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio trackingAFRICAN JOURNAL OF ECOLOGY, Issue 3 2001Frauke Fischer Abstract Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex-specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics. Résumé On a étudié par radio-télémétrie l'utilisation spatiale et temporelle de l'habitat par les cobes (Kobus kob kob) au Parc National de Comoé (en Côte d'Ivoire, Afrique de l'Ouest). On a équipé un total de 23 cobes de colliers radio et on les a suivis pendant 15 mois (pour certains). L'espace vital des mâles était plus petit et celui des femelles plus grand que ce à quoi on s'attendait d'après les modèles théoriques. Les mâles adultes couvraient une zone plus réduite que les femelles adultes et ne déplaçaient pas leur espace vital en fonction des saisons. Les distances parcourues chaque jour étaient les mêmes pour les deux sexes. Les cobes se déplaçaient moins la nuit que le jour, et couvraient de plus courtes distances pendant la saison des pluies. Alors qu'une augmentation du recouvrement entre espaces vitaux des femelles aboutissait à un taux supérieur d'associations entre individus, l'association d'adultes des deux sexes n'était pas liée au taux de recouvrement des espaces vitaux. On suggère que le comportement territorial des mâles et l'évitement des prédateurs par les femelles pourraient expliquer les différences, spécifiques au sexe, de la dimension de l'espace vital des adultes et la déviation par rapport aux dimensions prévues. On suppose que l'évitement des prédateurs est la raison principale de la limitation des déplacements de nuit ainsi qu'en saison des pluies. On suppose que le comportement reproducteur et l'écologie alimentaire déterminent le degré d'association entre membres de la même espèce. [source] Morphological variation of perch Perca fluviatilis in humic lakes: the effect of predator density, competition and prey abundanceJOURNAL OF FISH BIOLOGY, Issue 4 2010J. Kekäläinen Between and within-lake variations in morphology of perch Perca fluviatilis were studied in four humic lakes in eastern Finland. Perca fluviatilis were more streamlined and smaller headed in a lake with the highest abundance of cyprinids, but lowest abundance of predators (Lake Tuopanjärvi), indicating adaptation to planktivorous feeding and low predator density. Highest bodied fish were found from a lake with the lowest cyprinid but highest predator abundance (Lake Koppelojärvi), which conversely indicates adaptation to more effective predator avoidance. Furthermore, the length of the paired fins was longest in Lake Kinnasjärvi and Lake Tuopanjärvi, where the abundance of benthic macroinvertebrates was lowest, suggesting selection for more effective benthivory. Clear morphological differences of P. fluviatilis between habitats were found only in Lake Kinnasjärvi, whereas in Lake Koppelojärvi and Lake Tuopanjärvi only the length of the paired fins differed and in Lake Harkkojärvi no differences were found. Taken together, these results suggest that inter and intrapopulation morphological differences are probably highly dependent on different biotic factors (i.e. predation risk, resource availability and competition). Spatial and temporal variations in these factors may have a great effect on body morphology of P. fluviatilis. [source] Effects of the toxic dinoflagellate, Alexandrium fundyense on three species of larval fish: a food-chain approachJOURNAL OF FISH BIOLOGY, Issue 1 2008J. C. Samson Sublethal behavioural effects of exposure to paralytic shellfish toxins (PST; saxitoxin and its derivatives) from the toxic dinoflagellate Alexandrium fundyense were investigated in newly settled winter flounder Pseudopleuronectes americanus, larval sheepshead minnow Cyprinodon variegatus and larval mummichog Fundulus heteroclitus through an A. fundyense,copepod,fish food chain. Consumption of as few as six to 12 toxin-containing copepods was lethal to the fishes. After consuming fewer toxin-containing copepods, all three fish species exhibited sublethal effects from vector-mediated exposure. Prey-capture ability of mummichogs was reduced in larvae that had consumed toxic copepods, Coullana canadensis. After consuming toxic C. canadensis or mixed copepods, mummichog larvae had reduced swimming performance. Swimming activity was also significantly reduced in winter flounder after consuming toxic copepods, including time spent in motion and distance travelled. Prey capture and predator avoidance were reduced in first-feeding sheepshead minnow larvae that had consumed toxic dinoflagellate cells. Adverse effects on prey capture or predator avoidance may reduce larval survival and facilitate the transmission of PST through the food web. This study provides baseline information on sublethal effects of PST exposure on fishes using a novel food-chain approach with zooplankton as vectors. [source] Understanding fish habitat ecology to achieve conservation,JOURNAL OF FISH BIOLOGY, Issue 2005J. C. Rice Habitat science can provide the unifying concepts to bring together ecological studies of physiological tolerances, predator avoidance, foraging and feeding, reproduction and life histories. Its unifying role is built on two assumptions, imported from terrestrial habitat science and not always stated explicitly: that competition is present interspecifically and intraspecifically under at least some conditions, and that habitat features have some persistence and predictability in space and time. Consistent with its central conceptual position in ecology, habitat science has contributed importantly to scientific advice on pollution, coastal zone management and many other areas of environmental quality, although it has been largely divorced from developments in fish populations dynamics done in support of fisheries management. Commitments by most management agencies to apply an integrated, ecosystem approach to management of human activities in marine systems, poses new challenges to marine science advisors to management. Integrated management and ecosystem approaches both inherently require spatial thinking and spatial tools, making habitat science a particularly relevant advisory framework, particularly because of the unifying role of habitat in ecology. The basic mechanisms behind ocean biological dynamics, productivity, concentration and retention, however, present much weaker opportunities for competition and less persistence and predictability, weakening the foundations of theory and concepts behind current habitat science. The paper highlights the new types of thinking about ,habitat' that will be required, if habitat science is to meet the advisory needs of the new approaches to management. [source] Polyculture production of juvenile fishes for survival in natureJOURNAL OF FISH BIOLOGY, Issue 2004J. S. Burke Production of seed for stock enhancement projects requires consideration of the behavioural quality of the animals to be released in the wild. Our approach to improving behavioural quality of hatchery fish is to raise them in polyculture with the plants or animals that fish normally utilize as shelter in nature. Results suggest that such ,naturalized' systems provide a broad improvement in behaviour as both predator avoidance and feeding skills were improved relative to control hatchery fish. In addition fish in a naturalized system grew better and were more tolerant of stress than were fish reared by traditional hatchery methods. We hypothesize that the spatial heterogeneity of our ,naturalized' systems provided training in both hiding and seeking and that these activities improved feed conversion and stress tolerance. [source] Sex differences in behaviour as an indirect consequence of mating systemJOURNAL OF FISH BIOLOGY, Issue 4 2000A. E. Magurran A considerable literature has been devoted to documenting differences between the sexes. However, relatively little attention has hitherto been directed towards those differences that arise as an indirect consequence of mating system even though they can have profound implications for the daily lives of the animals involved. In this review we focus on differences in the non-reproductive behaviour of fish and relate these to sexual dimorphism in size and morphology, and to variance in fitness between the sexes. In line with our expectation, differences in distributional ecology, schooling, aggression, predator avoidance and foraging are exaggerated in sexually dimorphic species and polygamous mating systems. Nonetheless, the behaviour of males and females may also differ in sexually monomorphic and monogamous species. We conclude by highlighting promising directions for further research. [source] Sexual segregation in western grey kangaroos: testing alternative evolutionary hypothesesJOURNAL OF ZOOLOGY, Issue 2 2007A. M. MacFarlane Abstract In sexually dimorphic ungulates, sexual segregation is hypothesized to have evolved because of sex-specific differences in body size and/or reproductive strategies. We tested these alternative hypotheses in kangaroos, which are ecological analogues of ungulates. Kangaroos exhibit a wide range of body sizes, particularly among mature males, and so the effects of body size and sex can be distinguished. We tested predictions derived from these hypotheses by comparing the distribution of three sex,sex size classes of western grey kangaroos Macropus fuliginosus, in different habitats, and the composition of groups of kangaroos, across seasons. In accordance with the predation risk-reproductive strategy hypothesis, during the non-breeding season, females, which were more susceptible to predation than larger males, and were accompanied by vulnerable young-at-foot, were over-represented in secure habitats. Large males, which were essentially immune to predation, occurred more often than expected in nutrient-rich habitat, and small males, which faced competing demands of predator avoidance and feeding, were intermediate between females and large males in their distribution across habitats. During the breeding season, females continued to be over-represented in secure habitats when their newly emerged pouch young were most vulnerable to predation. All males occupied these same habitats to maximize their chances of securing mates. Consistent with the social hypotheses, groups composed of individuals of the same sex, irrespective of body size, were over-represented in the population during the non-breeding season, while during the breeding season all males sought females so that mixed-sex groups predominated. These results indicate that body size and reproductive strategies are both important, yet independent, factors influencing segregation in western grey kangaroos. [source] Mixed species groups in mammalsMAMMAL REVIEW, Issue 3-4 2003EVA STENSLAND ABSTRACT 1.,Mixed species groups have long been noted in birds, but they also occur among different species of mammals ranging from closely related species to species from different orders. Mixed species groups of mammals occur in many different habitats, e.g. ungulates on the savannah, primates in various types of forests and cetaceans in the oceans. Mixed species groups are very different in their duration, frequency, predominant activity and structure depending on the species interacting and the habitat they occur in. 2.,Functional explanations for mixed species groups usually fall within two categories: foraging advantages and predator avoidance. However, there could also be other social and reproductive advantages of mixed species groups that could contribute to their formation and stability. The advantages do not have to be equally distributed between the participating species and can also vary according to season and the presence of predators. 3.,It is important that all investigators of mixed species groups take their studies one step further after the naturalistic description and test the function and benefits of mixed species groups in order to give more strength to their conclusions. In this paper we review and discuss the function of mixed species groups in mammals and suggest an approach on how to investigate the function of such groups. [source] The transcriptomics of life-history trade-offs in whitefish species pairs (Coregonus sp.)MOLECULAR ECOLOGY, Issue 7 2008J. ST-CYR Abstract Despite the progress achieved in elucidating the ecological mechanisms of adaptive radiation, there has been little focus on documenting the extent of adaptive differentiation in physiological functions during this process. Moreover, a thorough understanding of the genomic basis underlying phenotypic adaptive divergence is still in its infancy. One important evolutionary process for which causal genetic mechanisms are largely unknown pertains to life-history trade-offs. We analysed patterns of gene transcription in liver tissue of sympatric dwarf and normal whitefish from two natural lakes, as well as from populations reared in controlled environments, using a 16 006-gene cDNA microarray in order to: (i) document the extent of physiological adaptive divergence between sympatric dwarf and normal species pairs, and (ii) explore the molecular mechanisms of differential life history trade-offs between growth and survival potentially involved in their adaptive divergence. In the two natural lakes, 6.45% of significantly transcribed genes showed regulation either in parallel fashion (2.39%) or in different directions (4.06%). Among genes showing parallelism in regulation patterns, we observed a higher proportion of over-expressed genes in dwarf relative to normal whitefish (70.6%). Patterns observed in controlled conditions were also generally congruent with those observed in natural populations. Dwarf whitefish consistently showed significant over-expression of genes potentially associated with survival through enhanced activity (energy metabolism, iron homeostasis, lipid metabolism, detoxification), whereas more genes associated with growth (protein synthesis, cell cycle, cell growth) were generally down-regulated in dwarf relative to normal whitefish. Overall, parallelism in patterns of gene transcription, as well as patterns of interindividual variation across controlled and natural environments, provide strong indirect evidence for the role of selection in the evolution of differential regulation of genes involving a vast array of potentially adaptive physiological processes between dwarf and normal whitefish. Our results also provide a first mechanistic, genomic basis for the observed trade-off in life-history traits distinguishing dwarf and normal whitefish species pairs, wherein enhanced survival via more active swimming, necessary for increased foraging and predator avoidance, engages energetic costs that translate into slower growth rate and reduced fecundity in dwarf relative to normal whitefish. [source] Foraging and mate-finding in the silver Y moth, Autographa gamma (Lepidoptera: Noctuidae) under the risk of predationOIKOS, Issue 2 2003Niels Skals Animal foraging and reproductive behaviour is influenced by other simultaneous demands such as predator avoidance. The trade-offs between these demands may depend on sex or mating experience. This study demonstrates that the olfactory-mediated foraging and mate-seeking behaviours in the silver Y moths, Autographa gamma, are affected by auditory cues mimicking their bat predators. Both males and females changed their foraging behaviour under simulated predation risk. Fewer moths reached the odour source following sound stimulation and the time to find the odour source increased by up to 250%. However, there were no significant differences between male and female ability to reach the plant odour source or the duration of the flight towards the source when stimulated with ultrasound. Hence females are not more cautious than males when observed in the same behavioural context. Risk-taking in males was independent of whether they were flying toward a flower odour or sex pheromones having equal attractive value. This indicates that the trade-off between olfactory and acoustic cues is independent the type of odour. Mated females were not as strongly affected by sound as non-mated, indicating that flower odours have a higher adaptive value for mated females, suggesting that some processes following mating experience influence the trade-off between flower odours and simulated bat sounds. [source] Comparison of responses to alarm calls by patas (Erythrocebus patas) and vervet (Cercopithecus aethiops) monkeys in relation to habitat structureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2002Karin L. Enstam Abstract We studied responses to alarm calls of sympatric patas (Erythrocebus patas) and vervet (Cercopithecus aethiops) monkeys in relation to habitat structure, with the intention of understanding the relationship between the environment and predator avoidance. Patas and vervet monkeys are phylogenetically closely related and overlap in body size. However, while patas monkeys are restricted to nonriverine habitats at our study site, vervets use both nonriverine and riverine habitats, allowing us to "vary" habitat structure while controlling for effects of group size, composition, and phylogeny. Patas monkeys in the nonriverine habitat responded to mammalian predator alarm calls with a greater variety of responses than did vervets in the riverine habitat, but not when compared with vervets in the nonriverine habitat. Ecological measurements confirm subjective assessments that trees in the riverine habitat are significantly taller and occur at lower densities than trees in the nonriverine habitat. Despite the lower density of trees in the riverine habitat, locomotor behavior of focal animals indicates that canopy cover is significantly greater in the riverine than the nonriverine habitat. Differences in responses to alarm calls by the same groups of vervets in different habitat types, and convergence of vervets with patas in the same habitat type, suggest that habitat type can be a significant source of variation in antipredator behavior of primates. Am J Phys Anthropol 119:3,14, 2002. © 2002 Wiley-Liss, Inc. [source] Chemical discrimination among predators by lizards: Responses of three skink species to the odours of high- and low-threat varanid predatorsAUSTRAL ECOLOGY, Issue 1 2009RAY LLOYD Abstract Animals must balance the benefits of predator avoidance with costs. Costs of predator avoidance, such as being forced to spend long periods inactive, should select for careful discrimination among predator species. Although prey responses to multiple predators have been well researched across many taxa, no studies have tested whether lizards discriminate among larger lizard predators. We examined the responses of three species of skink to two species of predatory goanna, one that occasionally consumes skinks, and the other a skink specialist. Three litter-dwelling, tropical skink species, Carlia rostralis, C. rubrigularis and C. storri, were given a choice between a retreat site treated with the odour of one of the goanna species, and an odourless control. The two goanna species used for stimulus scents were: Varanus tristis, a species that consumes skinks as a major proportion of its diet, and Varanus varius, a species that consumes skinks occasionally. Both goannas are broadly sympatric with all three skink species. Carlia rostralis and C. storri both avoided the scent of V. tristis, whereas C. rubrigularis did not. However, no skink species avoided the odour of V. varius. Prey are clearly able to avoid predators based on chemical cues, and can discriminate among similar predators that pose different levels of threat. [source] Morphological correlates of burst speed and field movement patterns: the behavioural adjustment of locomotion in wall lizards (Podarcis muralis)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2003FLORENTINO BRAÑA Locomotion of lizards has clear morphological determinants and is important for developing activities such as feeding, social interaction and predator avoidance. Thus, morphological variation is believed to have fitness consequences through affecting locomotor performance. This paper firstly evaluates the dependence of burst speed on morphology, and secondly examines the movement patterns of free-ranging undisturbed wall lizards (Podarcis muralis) engaged in several kinds of activity. Body size was the most important correlate of burst speed as performed at the optimal temperature for running in the laboratory. After removing size effects from performance and morphological traits, the length of some particular limb segments had positive influence on burst speed, but these effects were weak, each trait explaining less than 16% of variance in burst speed. Free-ranging P. muralis exhibited intermittent locomotion, with movement sequences interrupted by frequent short pauses. Field movement patterns greatly differed depending upon the kind of activity and were in most aspects independent of the size and sex of the animal. P. muralis involved in thermoregulation performed short and low-speed displacements; exploratory activities were characterized by frequent, slow and short movements. On the contrary, lizards involved in intraspecific pursuits and predator escape developed comparatively high speeds, although only exceptionally did they attain the size-specific burst speed predicted from the laboratory trials. Speed of escape increased with distance to the refuge and the animals are able to assess predation risks to modulate approach distance, speed and pauses, so maximum exertion is seldom required. The evolution of locomotor capacities exceeding routine needs is discussed in the context of the principle of ,excessive construction'. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 135,146. [source] Bird Assemblage and Visitation Pattern at Fruiting Elmerrillia tsiampaca (Magnoliaceae) Trees in Papua New GuineaBIOTROPICA, Issue 2 2010Steffen Oppel ABSTRACT Most tropical trees produce fleshy fruits that attract frugivores that disperse their seeds. Early demography and distribution for these tree species depend on the effects of frugivores and their behavior. Anthropogenic changes that affect frugivore communities could ultimately result in changes in tree distribution and population demography. We studied the frugivore assemblage at 38 fruiting Elmerrillia tsiampaca, a rain forest canopy tree species in Papua New Guinea. Elmerrillia tsiampaca is an important resource for frugivorous birds at our study site because it produces abundant lipid-rich fruits at a time of low fruit availability. We classified avian frugivores into functional disperser groups and quantified visitation rates and behavior at trees during 56 canopy and 35 ground observation periods. We tested predictions derived from other studies of plant,frugivore interactions with this little-studied frugivore assemblage in an undisturbed rain forest. Elmerrillia tsiampaca fruits were consumed by 26 bird species, but most seeds were removed by eight species. The most important visitors (Columbidae, Paradisaeidae and Rhyticeros plicatus) were of a larger size than predicted based on diaspore size. Columbidae efficiently exploited the structurally protected fruit, which was inconsistent with other studies in New Guinea where structurally protected fruits were predominantly consumed by Paradisaeidae. Birds vulnerable to predation foraged for short time periods, consistent with the hypothesis that predator avoidance enhances seed dispersal. We identified seven functional disperser groups, indicating there is little redundancy in disperser groups among the regular and frequent visitors to this tropical rain forest tree species. [source] | |||||||||||||||||||||||||