Moonlight and shelter cause differential seed selection and removal by rodents

Abstract

foraging ecology predation risk Queráis scatter hoarding seed size wood mouse Various environmental factors may influence the foraging behaviour of seed dispersers which could ultimately affect the seed dispersal process. We examined whether moonlight levels and the presence or absence of rodent shelter affect rodent seed removal (rate, handling time and time of removal) and seed selection (size and species) among seven oak species. The presence or absence of safe microhabitats was found to be more important than moonlight levels in the removal of seeds. Bright moonlight caused a different temporal distribution of seed removal throughout the night but only affected the overall removal rates in open microhabitats. Seeds were removed more rapidly in open microhabitat (regardless of the moon phase), decreasing the time allocated to seed discrimination and translocation. Only in open microhabitats did increasing levels of moonlight decrease the time allocated to selection and removal of seeds. As a result, a more precise seed selection was made under shelter, owing to lower levels of predation risk. Rodent ranking preference for species was identical between full/new moon in shelter but not in open microhabitats. For all treatments, species selection by rodents was much stronger than size selection. Nevertheless, heavy seeds, which require more energy and time to be transported, were preferentially removed under shelter, where there is no time restriction to move the seeds. Our findings reveal that seed selection is safety dependent and, therefore, microhabitats in which seeds are located (sheltered versus exposed) and moonlight levels in open areas should be taken into account in rodent food selection studies.

Seed Predation on the Ground or in the Tree? Size-Related Differences in Behavior and Ecology of Granivorous Birds

“…We expected a more rapid seed predation on the ground in agreement with the "reduced finickiness" hypothesis (Leaver & Daly 2003, Perea et al 2011 where animals search for food more rapidly and less selectively in areas with higher levels of predation risk. Our results revealed a slower seed predation on the ground in comparison to the tree only for Chaffinches (the species more accustomed to foraging on the ground of forests; Marler 1956, Kear 1962, Newton 1967, and therefore, an increase in vigilance time on the ground could be a trait favored by selection.…”

Predicting forest management effects on oak–rodent mutualisms

“…In fact, studies monitoring individual movements have found that home ranges shrink when exposure to predation increases (Tew and Macdonald , Tattersall et al ). Regarding foraging behavior, wood mice invest less effort in food selection and manipulation in risky environments than in safe ones (Perea et al ). In our model, the landscape matrix became more permeable, and consequently dispersal distances increased, when mice perceived lower predation risks or took riskier decisions.…”

Effects of forest fragmentation on the oak–rodent mutualism

“…This conditional mutualism depends on a fine balance in which environmental conditions shape rodents’ hoarding activity (Den Ouden et al , Theimer ). Key environmental factors that condition the outcome of the mouse–oak relationship by driving mouse behavior are: 1) intraspecific competition for acorns (defined as the ratio between local mouse abundance and acorn crop),which is related to the net benefits between in situ seed consumption versus hoarding, post‐dispersal acorn retrieval and the likelihood of cache pilferage by conspecifics (Theimer , Vander Wall ) and 2) the presence of shelter, which conditions mouse perception of predation risks while mobilizing seeds (Perea et al , ). Forest fragmentation may have major effects on these factors.…”