Optimal Foraging in Peromyscus Polionotus: the Influence of Item-Size and Predation Risk

Behaviour ◽  
1992 ◽  
Vol 121 (1-2) ◽  
pp. 95-109 ◽  
Author(s):  
John P. Phelan ◽  
Richard H. Baker
Keyword(s):  
Predation Risk ◽  
Optimal Foraging ◽  
Field Experiments ◽  
Behavioral Strategies ◽  
Seed Selection ◽  
Seed Type ◽  
Peromyscus Polionotus ◽  
Seed Preference ◽  
Risk Of Predation ◽  
Item Size

AbstractPredictions of optimal foraging theory were tested for Peromyscus polionotus in the laboratory and in two field experiments in which seed item-size was manipulated. In the laboratory, handling times for millet, sunflower seeds, and peanuts were determined. Additionally, energy/handling (E/h) time values were calculated and seed preference experiments were conducted. Mice showed a clear preference for the seeds more profitable in terms of E/h. Seed preference experiments were also conducted in the field to determine the relative influence of optimal foraging and predation risk in diet choice. In the first of the two field experiments, behavioral strategies to reduce predation vulnerability could not influence differential seed selection. As predicted, the mice again showed a preference for the more profitable seed type. In the second experiment, animals were presented with conflicting demands because foraging on a more abundant, but less preferred, seed type afforded the animal an increased ability to avoid predators. Presented with this opportunity to reduce the risk of predation, the animals shifted their preference to the safer, but less profitable food. This shift in seed preference was accompanied by predation-risk-reducing changes in spatial foraging patterns.

Optimal foraging and physiological responses to the risk of predation: how fecal cortisol concentrations from trapped Allenby’s gerbil (Gerbillus andersoni allenbyi) relate to foraging under the risk of predation

2019 ◽  
Vol 65 (1-2) ◽  
pp. 28-36 ◽  
Author(s):  
Justin R. St. Juliana ◽  
Burt P. Kotler ◽  
Berry Pinshow ◽  
Noga Kronfeld-Schor
Keyword(s):  
Predation Risk ◽  
Time Allocation ◽  
Optimal Foraging ◽  
Time Course ◽  
Stress Hormones ◽  
Cortisol Concentration ◽  
Corticosterone Concentration ◽  
Fecal Cortisol ◽  
Risk Of Predation ◽  
Time Course Experiment

We studied the influence of manipulating predation risk on Allenby’s gerbil ( Gerbillus andersoni allenbyi) held in a large, outdoor enclosure. We measured giving up densities (GUDs), apprehension, time allocation to foraging, harvest strategy (grab and go (GAG) vs. eat at tray (EAT)), and fecal cortisol concentration. First we established the time necessary for cortisol and corticosterone concentrations to change significantly from baseline after a stressful experience. To do this we collected feces from gerbils 2, 4, 6, or 8 hours after being handled (treatment) or not (control). After 8 h, fecal cortisol, but not corticosterone, concentration was significantly higher in treatment animals. We used the results from the hormone time course experiment to design the predation experiment. We used a dog, trained to harass gerbils, to increase predation risk for the gerbils. We predicted that fecal cortisol concentrations would increase directly in the face of predation risk, or indirectly, due to reduced foraging time because of perceived predation risk that, in turn, leads to increased hunger levels. As predicted, in the presence of a predator, GUDs were higher, time allocation lower, and GAG foraging was used more in treatment animals than in controls, but we found no change in apprehension. There was no difference in cortisol concentration between predator present and no-predator treatments. However, individuals that tended to have higher average fecal cortisol concentrations also tended, on average, to spend more time foraging. This indicates a relationship between stress hormones and optimal foraging. This relationship is potentially causal. While nightly changes in behavior may not be related to stress hormones, over course time scales, stress hormones may be driving gerbils to forage more.

Bumblebees avoid flowers containing evidence of past predation events

2006 ◽  
Vol 84 (9) ◽  
pp. 1240-1247 ◽  
Author(s):  
K.R. Abbott
Keyword(s):  
At Risk ◽  
Predation Risk ◽  
Field Experiments ◽  
The Other ◽  
Risk Of Predation ◽  
Series Of Experiments ◽  
Indirect Cues ◽  
Artificial Flowers ◽  
Ambush Predators

Bees are at risk of predation from flower-dwelling ambush predators. Since these predators tend to be cryptic, bees trying to mitigate predation risk may need to make use of indirect cues of the predator’s presence. For example, they may use cues of past predation events as indirect cues of current predation risk. I conducted a series of experiments that examined how bumblebees (genus Bombus Latreille, 1802) respond to cues of past predation events. In two field experiments, I found that wild rose (genus Rosa L.) flowers containing a freshly killed bumblebee, or the scent of a freshly killed bumblebee, received fewer bumblebee visits than control flowers. To test the possibility that bumblebees in the first two experiments were avoiding cues of competition risk rather than cues of predation risk, captive-reared bumblebees were given a choice between two artificial flowers — one containing a freeze-killed bumblebee (relatively more similar to a live foraging bee) and the other containing a crush-killed bumblebee (relatively more similar to a bee killed by a predator). Most bumblebees chose the flower containing the freeze-killed bee, supporting the hypothesis that the bumblebees in the first two experiments were attempting to avoid predation.

scholarly journals Aerial attack strategies of bat-hunting hawks, and the dilution effect of swarming

2020 ◽  
Author(s):  
Caroline H. Brighton ◽  
Lillias Zusi ◽  
Kathryn McGowan ◽  
Morgan Kinniry ◽  
Laura N. Kloepper ◽  
...  
Keyword(s):  
Predation Risk ◽  
Survival Rates ◽  
Dilution Effect ◽  
Strong Interactions ◽  
Behavioral Strategies ◽  
Tadarida Brasiliensis ◽  
Risk Of Predation ◽  
Column Formation ◽  
Order Of Magnitude ◽  
Buteo Swainsoni

AbstractAggregation behaviors can often reduce predation risk, whether through dilution, confusion, or vigilance effects, but these effects are challenging to measure under natural conditions, involving strong interactions between the behaviors of predators and prey. Here we study aerial predation of massive swarms of Brazilian free-tailed bats Tadarida brasiliensis by Swainson’s hawks Buteo swainsoni, testing how the behavioral strategies of predator and prey influence catch success and predation risk. The hawks achieved high overall catch success, but they were no more successful against lone bats than against bats flying in column formation. There was therefore no evidence of any net vigilance or confusion effect, and hawks attacking the column benefitted from the opportunity to make several attempted grabs. Even so, the bats’ overall risk of predation was an order of magnitude higher when flying alone. Attacks on lone bats (∼10% of attacks) were greatly overrepresented relative to the proportion of bats classified as flying alone (∼0.2%), so dilution is both necessary and sufficient to explain the higher survival rates of bats flying in the column. From the hawks’ perspective, their odds of catching a bat more than trebled if the attack involved a stoop rather than level flight, or a rolling rather than pitching grab maneuver. These behavioral tactics were independently deployed in nearly three-quarters of all attacks. Hence, whereas the survival rate of a bat depends principally on whether it flies alone or in a group, the catch success of a hawk depends principally on how it maneuvers to attack.Lay summaryBats emerging by daylight from a massive desert roost are able to minimise their predation risk by maintaining tight column formation, because the hawks that attack them target stragglers disproportionately often. Whereas the predation risk of a bat therefore depends on how it maintains its position within the swarm, the catch success of a hawk depends on how it maneuvers to attack. Catch success is maximised by executing a stooping dive or a rolling grab.

Do changes in reef habitats influence relative predation risk on the juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875)?

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 839-856 ◽  
Author(s):  
J. Hesse ◽  
J. A. Stanley ◽  
A. G. Jeffs
Keyword(s):  
Predation Risk ◽  
Spatial Scales ◽  
Spiny Lobster ◽  
Habitat Type ◽  
Small Spatial Scale ◽  
Important Species ◽  
Early Juvenile ◽  
Risk Of Predation ◽  
Jasus Edwardsii ◽  
Commercially Important

Kelp habitats are in decline in many temperate coastal regions of the world due to climate change and expansion of populations of grazing urchins. The loss of kelp habitat may influence the vulnerability to predators of the juveniles of commercially important species. In this study relative predation rates for kelp versus barren reef habitat were measured for early juvenile Australasian spiny lobster, Jasus edwardsii (Hutton, 1875), on the northeastern coast of New Zealand using tethering methods. Variation in assemblages of predators over small spatial scales appeared to be more important for determining the relative predation of lobsters, regardless of habitat type. Therefore, the assessment of relative predation risk to early juvenile lobsters between kelp and barren habitats will require more extensive sampling at a small spatial scale, as well as a specific focus on sampling during crepuscular and nocturnal periods when these lobsters are most at risk of predation.

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

2010 ◽  
Vol 37 (4) ◽  
pp. 273 ◽  
Author(s):  
Karen Fey ◽  
Peter B. Banks ◽  
Hannu Ylönen ◽  
Erkki Korpimäki
Keyword(s):  
Baltic Sea ◽  
Predation Risk ◽  
Myodes Glareolus ◽  
The Baltic Sea ◽  
Short Term ◽  
Behavioural Responses ◽  
Alien Predator ◽  
Risk Of Predation ◽  
The Baltic ◽  
The Impact

Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis) and a recently invading alien predator, the American mink (Mustela vison), in laboratory. We also studied the short-term responses of free-ranging field voles and bank voles (Myodes glareolus) to simulated predation risk by alien mink on small islands in the outer archipelago of the Baltic Sea. Key results. In the laboratory, voles avoided odour cues of native weasel but not of alien mink. It is possible that the response to mink is a context dependent learned response which could not be induced in the laboratory, whereas the response to weasel is innate. In the field, however, voles reduced activity during their normal peak-activity times at night as a response to simulated alien-mink predation risk. No other shifts in space use or activity in safer microhabitats or denser vegetation were apparent. Conclusions. Voles appeared to recognise alien minks as predators from their odours in the wild. However, reduction in activity is likely to be only a short-term immediate response to mink presence, which is augmented by longer-term strategies of habitat shift. Because alien mink still strongly suppresses vole dynamics despite these anti-predator responses, we suggest that behavioural naiveté may be the primary factor in the impact of an alien predator on native prey. Implications. Prey naiveté has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naiveté whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.

scholarly journals Effects of microhabitat on rodent-mediated seed removal of endangered Kmeria septentrionalis in the karst habitat

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10378
Author(s):  
Guohai Wang ◽  
Yang Pan ◽  
Guole Qin ◽  
Weining Tan ◽  
Changhu Lu
Keyword(s):  
Predation Risk ◽  
Rattus Norvegicus ◽  
Removal Rate ◽  
Soil Surface ◽  
Predation Rate ◽  
Seed Removal ◽  
Seed Type ◽  
Stone Surface ◽  
Broad Variety ◽  
High Removal Rate

Seed removal behaviors of rodents are largely influenced by microhabitat. Although the karst ecosystem is composed of a broad variety of microhabitats, we have no information on how they affect such behaviors. We investigated rodents’ seed removal behaviors in four karst microhabitats (stone cavern, stone groove, stone surface, and soil surface) using three types of Kmeria septentrionalis seeds: fresh, black (intact seeds with black aril that dehydrates and darkens), and exposed (clean seeds without the aril). We show that Rattus norvegicus, Leopoldamys edwardsi and Rattus flavipectus were the predominant seed predators. Even though all seed types experienced a high removal rate in all four microhabitats, but rodents preferentially removed seeds from the three stone microhabitats (stone caves: 69.71 ± 2.74%; stone surface: 60.53 ± 2.90%; stone groove: 56.94 ± 2.91%) compared to the soil surface (53.90 ± 2.92%). Seeds that had been altered by being exposed to the environment were more attractive to rodents than fresh seeds (76.25 ± 2.20% versus 36.18 ± 2.29%). The seed removal behavior of rodents was significantly affected by the microhabitat and seed type. Finally, seeds that had fallen on the soil surface microhabitat incurred a lower predation risk than seeds fallen on other microhabitats, which increased their probability to germinate. Our results indicate that the lower predation rate of seeds from the endangered K. septentrionalis dropped on the soil surface increases trees’ likelihood of survival.

scholarly journals Predation Risk by Gastronomic Boom - Case Peru

2018 ◽  
Vol 11 (1) ◽  
pp. 100-103
Author(s):  
Aldo Alvarez-Risco ◽  
Jaime Delgado-Zegarra ◽  
Jaime A. Yáñez ◽  
Santiago Diaz-Risco ◽  
Shyla Del-Aguila-Arcentales
Keyword(s):  
Natural Resources ◽  
Predation Risk ◽  
Environmental Sustainability ◽  
Natural Sources ◽  
Risk Of Predation ◽  
Significant Damage

Abstract The growth of tourism to Peru and the gastronomic boom with millions of people looking to taste Peruvian food is resulting in a risk of predation of natural sources necessary to make these dishes. The focus in only obtaining these ingredients can generate significant damage to the Peruvian biodiversity, so stakeholders need to develop strategies to avoid predation due to the gastronomic boom. Citizens and visitors need to play a role in protecting the natural resources and contributing to environmental sustainability.

Patterns of shelter use and their effects on the relative survival of subadult California spiny lobster (Panulirus interruptus)

2016 ◽  
Vol 67 (8) ◽  
pp. 1153 ◽  
Author(s):  
Amalia M. Harrington ◽  
Kevin A. Hovel
Keyword(s):  
Predation Risk ◽  
Field Experiments ◽  
Spiny Lobster ◽  
Relative Survival ◽  
Panulirus Interruptus ◽  
Rocky Reefs ◽  
Comprehensive Examination ◽  
Spiny Lobsters ◽  
Shelter Selection ◽  
Natural Reefs

Spiny lobsters use refuge habitat and gregarious behaviour to reduce predation risk, particularly in their vulnerable juvenile and subadult stages. We characterised patterns of sheltering behaviour in the California spiny lobster (Panulirus interruptus (Randall)) on southern California rocky reefs and used manipulative experiments to examine how these behaviours affect the survival of subadult lobsters and shelter selection. Lobsters generally were gregarious and subadults were commonly found inhabiting shelters with adult lobsters. Tethering experiments with subadults indicated that communal denning increases the odds of survival only when adult lobsters are part of aggregations. This corresponded to results from a shelter choice experiment in the laboratory, where the presence of predators caused subadults to shelter more often with adult conspecifics rather than other subadults. Despite the gregarious nature of P. interruptus, solitary subadults were common at all sites. Although field experiments clearly indicated that solitary lobsters increased their odds of survival by inhabiting shelters scaled to body size, evidence that lobsters exhibit shelter scaling on natural reefs was mixed. Our results indicate that subadult P. interruptus exhibit similar behavioural strategies as other spiny lobsters to reduce predation risk, and they provide a more comprehensive examination of P. interruptus behaviour than previously available.

Developmental costs of yellow colouration in fire salamanders and experiments to test the efficiency of yellow as a warning colouration

2020 ◽  
Vol 41 (3) ◽  
pp. 373-385 ◽  
Author(s):  
Barbara A. Caspers ◽  
E. Tobias Krause ◽  
Isabelle Hermanski ◽  
Christopher Wiesbrock ◽  
Friedrich-Wilhelm Kastrup ◽  
...  
Keyword(s):  
Predation Risk ◽  
Carabid Beetles ◽  
Colour Pattern ◽  
Natural Habitats ◽  
Yellow Colour ◽  
Risk Of Predation ◽  
Fire Salamander ◽  
Food Conditions ◽  
In Fire ◽  
Salamander Larvae

Abstract Warning colouration reduces predation risk by signalling or mimicking the unpleasantness of prey and therefore increases survival. We tested in two experiments the evolutionary costs and benefits of the yellow colour pattern in fire salamanders (Salamandra salamandra), which display a yellow/black colour pattern usually associated with toxic alkaloids. Our first experiment aimed to test whether the development of colouration is condition dependent and thus related to developmental costs, i.e. influenced by resource availability during the developmental process. Therefore, we reared fire salamander larvae under different nutritional conditions and compared the relative amount of yellow they developed after metamorphosis. Fire salamander larvae reared under limited food conditions had a lower proportion of yellow following metamorphosis than control larvae reared under superior food conditions. In a second experiment we tested whether the proportion of yellow has an impact on the risk of being attacked using artificial models. We tested, in salamander-free and salamander-occupied natural habitats, whether artificial clay models with different proportions of yellow and black receive different attack rates from potential predators (birds, mammals, insects). In clay models the proportion of yellow and the site had a significant effect on predation risk. Models with larger amounts of yellow had fewer bite marks from predators such as carabid beetles and birds, but only in sympatry with salamanders. In conclusion, the early expression of conspicuous colouration seems to be condition dependent and therefore potentially costly. Furthermore, the yellow colouration of fire salamanders act as a signal that potentially reduces their risk of being attacked by predators. Thus, the yellow colouration of fire salamanders seems to represent an adaptive trait that reduces the risk of predation, which can be expressed in higher quantity by individuals of a certain condition.

SCREAMING AS A STRATEGY TO REDUCE THE PREDATION RISK INCURRED BY BEGGING?

Behaviour ◽  
2001 ◽  
Vol 138 (5) ◽  
pp. 615-627 ◽  
Author(s):  
Keyword(s):  
Predation Risk ◽  
Feeding Rate ◽  
Honest Signal ◽  
Apparent Paradox ◽  
Signalling System ◽  
Comparative Analyses ◽  
Risk Of Predation ◽  
Food Requirement ◽  
Per Se ◽  
High Degree

AbstractFollowing the theory of parent-offspring conflict parents request from their offspring an honest signal of food requirement to optimally adjust feeding rate. For this purpose, offspring display a highly informative signalling system, begging vocalisation, for which the conspicuousness to predators maintains honesty, since only hungry offspring are willing to take this risk. The risk of predation incurred by begging activities challenges our understanding of how begging vocalisation could evolve towards a high degree of noisiness. A solution to this apparent paradox resides in the possibility that alongside the evolution of begging, birds also evolved strategies that reduce the risk of being depredated. Following the ornithological literature nestlings scream in the presence of a predator to frighten it, induce parents to rescue them and siblings to flee from the nest and hide in the vegetation. I therefore propose the hypothesis that nestling screaming behaviour evolved as a means of reducing the risk of predation incurred by conspicuous begging. Comparative analyses supported the prediction postulating that species in which nestlings scream in the presence of a predator produce begging calls that are more conspicuous to predators than calls of non-screaming species. This suggests that the predation cost of begging lies not only in terms of predation per se but also in the requirement of anti-predator strategies.

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