High predation risk for a small mammal: the eastern pygmy-possum (Cercartetus nanus)

2013 ◽  
Vol 35 (2) ◽  
pp. 149 ◽  
Author(s):  
Bradley Law ◽  
Mark Chidel ◽  
Alf Britton
Keyword(s):  
Predation Risk ◽  
Small Mammal ◽  
High Predation ◽  
Cercartetus Nanus

We report high rates of predation within a population of eastern pygmy-possum (Cercartetus nanus) near Sydney, observed during a study of the impacts of logging on the species. Predation by reptiles was observed on six of 61 radio-tracked pygmy-possums, while two were suspected of being taken by raptors. We further investigated predation by sooty owls (Tyto tenebricosa) by identifying remains in pellets. Pygmy-possums comprised 15% of the 126 dietary items identified. Predation occurred at both logged and unlogged sites in our study. We suggest that documented high rates of predation in our study could make the species vulnerable to altered predation regimes, such as influxes of feral predators, and highlight the need for a better understanding of any influence of logging on predator activity.

Impact of high predation risk on genome-wide hippocampal gene expression in snowshoe hares

Oecologia ◽  
2014 ◽  
Vol 176 (3) ◽  
pp. 613-624 ◽  
Author(s):  
Sophia G. Lavergne ◽  
Patrick O. McGowan ◽  
Charles J. Krebs ◽  
Rudy Boonstra
Keyword(s):  
Gene Expression ◽  
Predation Risk ◽  
Snowshoe Hares ◽  
Genome Wide ◽  
High Predation

Some like it cool? Intermorph comparison of preferred body temperature in a colour-dimorphic snake

2009 ◽  
Vol 59 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Koji Tanaka
Keyword(s):  
Body Temperature ◽  
Environmental Factors ◽  
Laboratory Experiment ◽  
Predation Risk ◽  
Field Studies ◽  
Behavioural Thermoregulation ◽  
Model Species ◽  
High Predation ◽  
Preferred Body Temperature ◽  
Recent Laboratory

AbstractOrganismal characteristics of ectotherms are profoundly affected by body temperature (Tb). Despite constraints imposed by environmental factors, they can adjust Tb by several means. However, if thermoregulatory ability is limited by their own property such as coloration and this constraint affects individual's fitness, selection may promote coevolution of coloration and thermal aspects. I investigated this topic using a colour-dimorphic (melanistic/striped) snake Elaphe quadrivirgata as a model species. Recent laboratory experiment revealed slower body warming in striped individuals than in melanistic individuals. Under this circumstance, one way that striped individuals can manage their slower body warming is to prefer low Tb. Contrary to this prediction, there was no intermorph difference in preferred Tb. Coupled with the results of field studies, I suggest that striped individuals manage their slower body warming by behavioural thermoregulation and that constraints (e.g., high predation risk due to conspicuousness under thermally superior habitats) imposed on melanistic individuals lessen their thermal advantages. The effect of melanism on thermal aspects may not be so advantageous for melanistic animals than generally thought.

Habitat as a source of intrapopulational variation of ornament size in Galápagos lava lizards (Microlophus albemarlensis complex)

2008 ◽  
Vol 29 (2) ◽  
pp. 278-283 ◽  
Author(s):  
Mark Jordan ◽  
Howard Snell ◽  
Jennifer Hollis ◽  
Paul Stone
Keyword(s):  
Predation Risk ◽  
Body Mass ◽  
Predator Avoidance ◽  
Habitat Structure ◽  
Predation Pressure ◽  
Residual Body ◽  
Galápagos Islands ◽  
Vegetative Cover ◽  
High Predation ◽  
Intrapopulational Variation

Abstract Gradients in habitat structure are expected to influence the outcome of selection on traits that contribute to communicative display. Galápagos lava lizards (Microlophus albemarlensis complex) on Isla Plaza Sur in the Galápagos Islands occur across a gradient of vegetative cover. Previous work in this population has shown that traits associated with predator avoidance are magnified in habitats with low vegetative cover. This pattern suggests that predation pressure differs by habitat and thus, may act to select against the elaboration of ornamentation. We measured the size of the chin patch, an ornament known to be used in intraspecific signaling, to test this hypothesis. The area of the chin patch was dependent on both snout-vent length and residual body mass. In contrast to expectation, males had larger chin patches in the sparsely vegetated habitat suggested to have high predation risk. This result raises questions about the presumed survival cost of ornament elaboration.

Differential effects of predation risk and competition over vigilance variables and feeding success in Eurasian siskins (Carduelis spinus)

Behaviour ◽  
2013 ◽  
Vol 150 (14) ◽  
pp. 1665-1687 ◽  
Author(s):  
Jordi Pascual ◽  
Juan Carlos Senar
Keyword(s):  
Food Intake ◽  
Predation Risk ◽  
Foraging Behaviour ◽  
Interference Competition ◽  
Ecological Factors ◽  
Intake Rate ◽  
Similar Length ◽  
Feeding Success ◽  
High Predation ◽  
Food Intake Rate

Many investigations have studied the effects of predation risk and competition over vigilance and feeding success, but they have proven to be difficult to discriminate. Moreover, none of the studies that have avoided the confusion has considered all the vigilance variables, food intake rate and time spent in the foraging patch. In this study, we designed an experiment with Eurasian siskinsCarduelis spinusforaging on three bird table feeders: one with low predation risk and competition, one with low predation risk and high competition and one with high predation risk and intermediate competition. Birds responded to increasing interference competition by increasing mean scan durations (probably due to the birds having to be vigilant for both other flock members and predators) and maintaining the length of mean inter-scan durations, while they responded to increasing predation risk by reducing mean inter-scan durations (probably in order to detect the predator sooner) while maintaining similar length of mean scan durations. Birds were often ejected from the feeder or departed because of disturbances, so time spent on feeders was reduced both because of competition and predation risk. Pecking rates were affected by competition but not by predation risk. Our results clearly show that birds vigilance strategy while foraging might be very different when they are mainly concerned with scanning for predators or when they primarily monitor competing flock companions. In addition, they stress the importance of recording all the vigilance and feeding variables when studying the effect of ecological factors over the foraging behaviour of birds.

scholarly journals Trophic shift and the origin of birds

2020 ◽  
Author(s):  
Yonghua Wu
Keyword(s):  
Predation Risk ◽  
Digestive System ◽  
Predation Pressure ◽  
Flapping Flight ◽  
Foraging Efficiency ◽  
Fat Digestion ◽  
Trophic Shift ◽  
High Predation ◽  
High Predation Pressure ◽  
Selection Of

AbstractBirds are characterized by evolutionary specializations of both locomotion (e.g., flapping flight) and digestive system (toothless, crop, and gizzard), while the potential selection pressures responsible for these evolutionary specializations remain unclear. Here we used a recently developed molecular phyloecological method to reconstruct the diets of the ancestral archosaur and of the common ancestor of living birds (CALB). Our results showed that the ancestral archosaur exhibited a predominant Darwinian selection of protein and fat digestion and absorption, whereas the CALB showed a marked enhanced selection of carbohydrate and fat digestion and absorption, suggesting a trophic shift from carnivory to herbivory (fruit, seed, and/or nut-eater) at the archosaur-to-bird transition. The evolutionary shift of the CALB to herbivory may have essentially made them become a low-level consumer and, consequently, subject to relatively high predation risk from potential predators such as gliding maniraptorans, from which birds descended. Under the relatively high predation pressure, ancestral birds with gliding capability may have then evolved not only flapping flight as a possible anti-predator strategy against gliding predatory maniraptorans but also the specialized digestive system as an evolutionary tradeoff of maximizing foraging efficiency and minimizing predation risk. Our results suggest that the powered flight and specialized digestive system of birds may have evolved as a result of their tropic shift-associated predation pressure.

scholarly journals Why lemmings have indoor plumbing in summer

1996 ◽  
Vol 74 (10) ◽  
pp. 1947-1949 ◽  
Author(s):  
Rudy Boonstra ◽  
Charles J. Krebs ◽  
Alice Kenney
Keyword(s):  
Predation Risk ◽  
Ultraviolet Light ◽  
Canadian Arctic ◽  
Falco Tinnunculus ◽  
Vegetation Growth ◽  
Hunting Activity ◽  
Microtine Rodents ◽  
Dicrostonyx Groenlandicus ◽  
High Predation ◽  
Buteo Lagopus

The faeces and urine of microtine rodents are visible in ultraviolet light, and diurnal raptors, such as European kestrels (Falco tinnunculus) and rough-legged buzzards (Buteo lagopus), have the ability to see in ultraviolet light. It has been reported that in Fennoscandia, these raptors use this ability to concentrate their hunting activity in spring on areas where microtines are abundant. We hypothesized that in arctic tundra areas in summer, intense avian predation pressure and short vegetation should select for microtine behaviour that would minimize their exposure to these raptors. We dug up 62 collared lemming (Dicrostonyx groenlandicus) burrows in the Canadian Arctic and all had underground latrines. Latrines are not hidden underground in winter, when lemmings live under the snow, build nests above ground, and defecate above ground, nor does this occur in microtine species living in temperate areas, where summer vegetation growth is greater. Thus, high predation risk may influence not only where prey forage but also where they defecate.

scholarly journals Compensatory foraging in Trinidadian guppies: Effects of acute and chronic predation threats

2014 ◽  
Vol 60 (3) ◽  
pp. 323-332 ◽  
Author(s):  
Chris K. Elvidge ◽  
Indar Ramnarine ◽  
Grant E. Brown
Keyword(s):  
Predation Risk ◽  
Predator Avoidance ◽  
Short Term ◽  
Graded Responses ◽  
Trade Offs ◽  
Behavioral Mechanism ◽  
Low Concentrations ◽  
High Predation ◽  
Threat Levels

Abstract In response to acute predation threats, prey may sacrifice foraging opportunities in favour of increased predator avoidance. Under conditions of high or frequent predation risk, such trade-offs may lead to reduced fitness. Here, we test the prediction that prey reduce the costs associated with lost opportunities following acute predation threats by exhibiting short-term compensatory foraging responses. Under semi-natural conditions, we exposed female guppies Poecilia reticulate from high and low predation risk sites to one of three levels of acute predation threat (high, intermediate or low concentrations of conspecific alarm cues). Our results confirm previous reports, demonstrating that guppies from a high predation site were consistently ‘bolder’ (shorter escape latencies) and exhibited graded threat-sensitive responses to different simulated threat levels while those from the low predation site were ‘shyer’ and exhibited non-graded responses. Most importantly, we found that when guppies from low predation sites resumed foraging, they did so at rates significantly lower than baseline rates. However, guppies from high predation sites resumed foraging either at rates equal to baseline (in response to low or intermediate risk stimuli) or significantly increased relative to baseline rates (in response to high risk stimuli). Together, these results highlight a complex compensatory behavioral mechanism that may allow prey to reduce the long-term costs associated with predator avoidance.

Effects of Predation Risk and Parasitism on the Feeding Ecology, Habitat Use, and Abondance of Lacustrine Threespine Stickleback (Gasterosteus aculeatus)

1988 ◽  
Vol 45 (3) ◽  
pp. 426-431 ◽  
Author(s):  
Per Johan Jakobsen ◽  
Geir Helge Johnsen ◽  
Petter Larsson
Keyword(s):  
Predation Risk ◽  
Salmo Salar ◽  
Littoral Zone ◽  
Gasterosteus Aculeatus ◽  
Population Decline ◽  
Length Distribution ◽  
Threespine Stickleback ◽  
Selective Predation ◽  
Restricted Area ◽  
High Predation

From 1980 to 1985, we investigated a lacustrine population of threespine stickleback (Gasterosteus aculeatus) with respect to densities, individual length, distribution, diet, frequency of parasitism by Schistocepbalus solidus, and selective predation by Atlantic salmon (Salmo salar). From these investigations we concluded the following. (1) When stickleback are forced into the littoral zone by salmon, competition in this restricted area increases, or alternatively, stickleback distribute themselves in an area with less profitable prey. This, combined with predation from salmon, results in a population decline and reduced growth of the stickleback. (2) At least in autumn, parasitized stickleback distribute themselves in areas with high predation risk from salmon; when exposed to salmon predation, parasitized stickleback are preyed upon at a higher rate than healthy ones. Hence, parasitized individuals have almost disappeared from the stickleback population in Lake Kvernavann, Norway.

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