Covariance between predation risk and nutritional preferences confounds interpretations of giving-up density experiments

Jordan D. McMahon; Marcus A. Lashley; Christopher P. Brooks; Brandon T. Barton

doi:10.1002/ecy.2365

Welcome to the Dark Side: Partial Nighttime Illumination Affects Night-and Daytime Foraging Behavior of a Small Mammal

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.779825 ◽

2022 ◽

Vol 9 ◽

Author(s):

Julia Hoffmann ◽

Franz Hölker ◽

Jana A. Eccard

Keyword(s):

Predation Risk ◽

Foraging Behavior ◽

Small Mammal ◽

Interspecific Interactions ◽

Dark Side ◽

Natural Light ◽

Giving Up Density ◽

Night And Day ◽

Carry Over ◽

Perceived Predation Risk

Differences in natural light conditions caused by changes in moonlight are known to affect perceived predation risk in many nocturnal prey species. As artificial light at night (ALAN) is steadily increasing in space and intensity, it has the potential to change movement and foraging behavior of many species as it might increase perceived predation risk and mask natural light cycles. We investigated if partial nighttime illumination leads to changes in foraging behavior during the night and the subsequent day in a small mammal and whether these changes are related to animal personalities. We subjected bank voles to partial nighttime illumination in a foraging landscape under laboratory conditions and in large grassland enclosures under near natural conditions. We measured giving-up density of food in illuminated and dark artificial seed patches and video recorded the movement of animals. While animals reduced number of visits to illuminated seed patches at night, they increased visits to these patches at the following day compared to dark seed patches. Overall, bold individuals had lower giving-up densities than shy individuals but this difference increased at day in formerly illuminated seed patches. Small mammals thus showed carry-over effects on daytime foraging behavior due to ALAN, i.e., nocturnal illumination has the potential to affect intra- and interspecific interactions during both night and day with possible changes in personality structure within populations and altered predator-prey dynamics.

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Fight for Life

The American Biology Teacher ◽

10.1525/abt.2015.77.9.8 ◽

2015 ◽

Vol 77 (9) ◽

pp. 693-698 ◽

Cited By ~ 1

Author(s):

Jennifer M. Clark ◽

Matthew T. Begley

Keyword(s):

Predation Risk ◽

Optimal Foraging ◽

Optimal Foraging Theory ◽

Foraging Theory ◽

Competitive Interactions ◽

Predator Prey ◽

Trade Offs ◽

Ecological Concepts ◽

Energy Trade ◽

Giving Up Density

Optimal foraging theory explains that organisms whose foraging is as energetically efficient as possible should be favored by natural selection. However, many individuals must exhibit trade-offs between foraging and other factors in their environment (i.e., predation risk, competitive interactions). We present a hands-on activity for undergraduates using just a deck of cards, bingo chips, and dice to introduce ecological concepts of foraging theory, predator–prey interactions, and energy trade-offs. Specifically, this activity will focus on optimal foraging theory and giving-up density. Students should gain an understanding of how organisms balance predation risk and competitive interactions with energetic demands. Further, this activity can be scaled for nonmajors and introductory courses to introduce general ecological concepts, or for upper-division courses to explore advanced topics in foraging theory.

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The influence of predation risk on foraging behaviour of brushtail possums in Australian woodlands

Wildlife Research ◽

10.1071/wr03098 ◽

2005 ◽

Vol 32 (2) ◽

pp. 121 ◽

Cited By ~ 31

Author(s):

Karolyne N. Pickett ◽

David S. Hik ◽

Alan E. Newsome ◽

Roger P. Pech

Keyword(s):

Reproductive Success ◽

Predation Risk ◽

Body Condition ◽

Foraging Behaviour ◽

Red Fox ◽

Conservation Strategies ◽

Habitat Types ◽

Lethal Effects ◽

Giving Up Density ◽

Cypress Pine

The potential effects of predation risk on common brushtail possums were investigated in south-eastern Australian woodlands. Patterns of habitat use, foraging costs using giving-up density (GUD) experiments, and indices of body condition and reproductive success were examined at eight sites in two habitat types (eucalypt- or cypress-pine–dominated stands), within three areas of different red fox abundance (high, moderate and low fox density). In cypress-pine–dominated stands, possums travelled further on the ground, visited more feeding stations and had lower GUDs at feeders where foxes were removed than did possums in high-fox-density sites. In contrast, there was no effect of fox removal on the behaviour of possums in eucalypt-dominated stands. Fox removal also had no effect on indices of body condition and reproduction. Minor effects of microhabitat were detected with trackplot and GUD experiments, but, overall, the results suggest that habitat at the stand-level was more important. The non-lethal effects of foxes in different habitats may need to be taken into account when developing conservation strategies for native marsupials.

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Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

10.32942/osf.io/h2mpw ◽

2019 ◽

Author(s):

Gretchen F. Wagner ◽

Emeline Mourocq ◽

Michael Griesser

Keyword(s):

Predation Risk ◽

Reproductive Cycle ◽

Perceived Risk ◽

Nest Predation ◽

Bird Species ◽

Size Variation ◽

Egg Laying ◽

Offspring Size ◽

Natural Predation ◽

Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

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