Responses of coal tits (Periparus ater) to aversive food: insights into hoarding motivation and memory.

Food-hoarding birds hide many different food types, and are able to remember which kind of food they have hidden and where it was located. Usually, these different food types, although potentially of different value to the birds, are all palatable and would be consumed when encountered. We report on the responses of coal tits (Periparus ater) to peanut pieces that were made distasteful with quinine. While birds preferred eating normal peanut pieces over quinine-soaked ones, they were still very likely to hoard the distasteful nuts. Birds also did not distinguish between the two nut types when retrieving them after 30 min. These findings point towards the compulsive and automatic nature of hoarding decision, independent of the value of the food being hoarded. We discuss how high hoarding motivation may interact with eating motivation to drive natural patterns of hoarding intensity in the field. Our findings also suggest that the taste of hoarded food items is not part of the representation of the cache memory. We speculate that this may be because tasting the item and caching the item happens in separate locations and are therefore not associated with each other.