School of Biology, University of St Andrews, St Andrews KY16 9TH, UK.
Department of Biological Sciences, University of Lethbridge, Alberta, Canada.
Proc Biol Sci. 2020 Jul 8;287(1930):20201269. doi: 10.1098/rspb.2020.1269.
Ordinality is a numerical property that nectarivores may use to remember the specific order in which to visit a sequence of flowers, a foraging strategy also known as traplining. In this experiment, we tested whether wild, free-living rufous hummingbirds () could use ordinality to visit a rewarded flower. Birds were presented with a series of linear arrays of 10 artificial flowers; only one flower in each array was rewarded with sucrose solution. During training, birds learned to locate the correct flower independent of absolute spatial location. The birds' accuracy was independent of the rewarded ordinal position (1st, 2nd, 3rd or 4th), which suggests that they used an object-indexing mechanism of numerical processing, rather than a magnitude-based system. When distance cues between flowers were made irrelevant during test trials, birds could still locate the correct flower. The distribution of errors during both training and testing indicates that the birds may have used a so-called working up strategy to locate the correct ordinal position. These results provide the first demonstration of numerical ordinal abilities in a wild vertebrate and suggest that such abilities could be used during foraging in the wild.
有序性是一种数值属性，食蜜动物可能会利用它来记住访问一系列花朵的特定顺序，这是一种也被称为“traplining”的觅食策略。在这个实验中，我们测试了野生、自由生活的红腹吸蜜鸟是否可以使用有序性来访问奖励花朵。研究人员向鸟类展示了一系列线性排列的 10 朵人工花；每个花列中只有一朵花用蔗糖溶液奖励。在训练过程中，鸟类学会了独立于绝对空间位置找到正确的花。鸟类的准确性与奖励的顺序位置（第一、第二、第三或第四）无关，这表明它们使用了一种基于对象索引的数值处理机制，而不是基于大小的系统。当在测试试验中使花朵之间的距离线索变得无关紧要时，鸟类仍然可以找到正确的花。在训练和测试期间，错误的分布表明鸟类可能使用了所谓的“工作向上”策略来定位正确的顺序位置。这些结果首次证明了野生脊椎动物的数值有序能力，并表明这些能力可能在野外觅食中被使用。
