Cognitive aspects of risky foraging: great tits go for less (#157)
The risk in risk-sensitive foraging is usually considered in the form of metabolic loss while handling prey and searching for new food patches, rather than in the form of danger coming from the prey. Here we consider a situation where the prey itself is dangerous. We simulated the situation of risky hunting in the great tits Parus major in order to examine whether these birds are able to make a choice between small and large quantities of live prey, both tasty and dangerous. We use red wood ants Formica aquilonia with whom passerine birds share territories in forest habitats. Our experiments reflect the natural situation when great tits face aggressive red wood ants within tree crowns and sometimes use them to feed chicks. It has been demonstrated that in similar experiments with ants field striped mice always tend to prefer the smaller quantity of dangerous prey (Panteleeva et al., 2013). We placed tits one by one into specially designed transparent cages divided into two parts. The bird was placed into the entrance part where it could evaluate the situation during one minute. Then the bird was allowed to enter the working part of the cage where it could choose between two glass feeders (“food patches”) containing ant groups of different quantities, from 5 to 50. Ants behaved rather aggressively, and they served both as food items and as a source of danger. We found that birds choose at random between 5 and 10, and they prefer more ants when choosing between 10 and 25. This means that tits value ants as food and quantities in this range do not bother them much. However they always go for the smaller quantity when choosing between 10 and 50 ants, thus displaying the capacity for distinguishing between more and less in order to ensure comfortable hunting.
The study has been supported by the Russian Scientific Fund (14-14-00603)