Scheid Christelle, Bugnyar Thomas
IPHC-DEPE, ULP, CNRS, 23 rue Becquerel, 67087, Strasbourg, France.
Anim Cogn. 2008 Oct;11(4):691-8. doi: 10.1007/s10071-008-0160-5. Epub 2008 May 27.
Observational spatial memory (OSM) refers to the ability of remembering food caches made by other individuals, enabling observers to find and pilfer the others' caches. Within birds, OSM has only been demonstrated in corvids, with more social species such as Mexican jays (Aphelocoma ultramarine) showing a higher accuracy of finding conspecific' caches than less social species such as Clark's nutcrackers (Nucifraga columbiana). However, socially dynamic corvids such as ravens (Corvus corax) are capable of sophisticated pilfering manoeuvres based on OSM. We here compared the performance of ravens and jackdaws (Corvus monedula) in a short-term OSM task. In contrast to ravens, jackdaws are socially cohesive but hardly cache and compete over food caches. Birds had to recover food pieces after watching a human experimenter hiding them in 2, 4 or 6 out of 10 possible locations. Results showed that for tests with two, four and six caches, ravens performed more accurately than expected by chance whereas jackdaws did not. Moreover, ravens made fewer re-visits to already inspected cache sites than jackdaws. These findings suggest that the development of observational spatial memory skills is linked with the species' reliance on food caches rather than with a social life style per se.
观察性空间记忆（OSM）是指记住其他个体所藏食物的能力，使观察者能够找到并窃取其他个体的藏物。在鸟类中，OSM仅在鸦科鸟类中得到证实，像墨西哥松鸦（Aphelocoma ultramarine）这样社交性更强的物种，在找到同种个体的藏物方面比像克拉克胡桃雀（Nucifraga columbiana）这样社交性较弱的物种表现出更高的准确性。然而，像渡鸦（Corvus corax）这样社交动态性较强的鸦科鸟类能够基于OSM进行复杂的窃取策略。我们在此比较了渡鸦和寒鸦（Corvus monedula）在一项短期OSM任务中的表现。与渡鸦不同，寒鸦具有很强的社会凝聚力，但几乎不藏物且不会争夺食物藏物。鸟类需要在观看人类实验者将食物块藏在10个可能位置中的2个、4个或6个位置后找回食物块。结果表明，在有2个、4个和6个藏物的测试中，渡鸦的表现比随机预期更准确，而寒鸦则不然。此外，渡鸦对已经检查过的藏物地点的再次访问次数比寒鸦少。这些发现表明，观察性空间记忆技能的发展与物种对食物藏物的依赖有关，而不是与社会生活方式本身有关。
