Front Psychol. 2013 Feb 13;4:53. doi: 10.3389/fpsyg.2013.00053. eCollection 2013.
- 1Institute of Systematics and Ecology of Animals, Russian Academy of Science Novosibirsk, Russia ; Novosibirsk State University Novosibirsk, Russia.
Abstract
We simulated the situation of risky hunting
in the striped field mouse Apodemus agrarius in order to examine
whether these animals are able to make a choice between small and large
quantities of live prey (ants). In the first (preliminary) experiment we
investigated to what extent mice were interested in ants as a live prey
and how their hunting
activity depended on the quantity of these edible but rather aggressive
insects. We placed mice one by one into arenas together with ant groups
of different quantities, from 10 to 60. Surprisingly, animals, both
wild-caught and laboratory-reared, displayed rather skilled predatory
attacks: mice killed and ate from 0.37 ± 003 to 4 ± 0.5 ants per minute.
However, there was a threshold number of ants in the arenas when
rodents expressed signs of discomfort and started to panic, likely
because ants bit them. This threshold corresponds to the dynamic density
(about 400 individuals per m(2) per min) in the vicinity of anthills
and ants' routes in natural environment. In the second experiment mice
had to choose between different quantities of ants placed in two
transparent tunnels. Ants here served both as food items and as a source
of danger. As far as we know, this is the first experimental paradigm
based on evaluation of quantity judgments in the context of risk/reward
decision making where the animals face a trade-off between the
hedonistic value of the prey and the danger it presents. We found that
when mice have to choose between 5 vs. 15, 5 vs. 30, and 10 vs. 30 ants,
they always tend to prefer the smaller quantity, thus displaying the
capacity for distinguishing more from less in order to ensure
comfortable hunting.
The results of this study are ecologically relevant as they reflect
situations and challenges faced by free-living small rodents.
KEYWORDS:
ants; behavioral ecology; cognition; decision making; feeding patches; quantity judgments; risky hunting; rodents
