Poor observational memory ability in food hoarding parids (#511)
At northern latitudes members of the parid family (tits and chickadees) use two entirely different over wintering strategies. Most species, such as willow tits, marsh tits and black-capped chickadees store large amounts of seeds and nuts in large year-round territories in which they are residents. The stored supplies constitute an important part of the winter sustenance. Two parid species, the great and blue tits, are not territorial in winter. These species do not store food and especially the great tit is known to be unusually innovative an explorative. In winter great tits frequently roam around exploring possible new food sources. The great tit is the largest parid in Europe and it regularly follows its smaller food hoarding relatives to steal cached food. In an indoor experiment we have demonstrated that caged great tits can observe caching marsh tits from a distance and later return and pilfer the cache. Such memorization is complex, since it requires an allocentric perspective, i. e. an ability to see the caching site from another individual’s perspective. In nature, female great tits are subordinate to males meaning that they are displaced at food sources. To compensate for this female great tits have developed an especially good ability for “observational cache memorization”. Remarkably, female great tits that have observed a marsh tit cache are as good as the cacher itself in relocating caches. In a second indoor experiment we tested observational memorization in marsh tits in the same set up as the great tits. They showed no ability to memorize locations of caches made by conspecifics. This was according to our expectation, since a hoarder that memorized lots of own caches need not to bother with the more difficult task to memorize caches made by others.