Failure of a Free-living Northern Mockingbird (Mimus polyglottos) to Discriminate Food Rewards on the Basis of Number

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2005-09

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Abstract

Spontaneous numerical discrimination has been observed in animals in laboratory and field studies. These studies often rely on subjects choosing the most profitable food items. I designed a feeding apparatus to explore the spontaneous numerical discrimination of a free-living northern mockingbird (Mimus polyglottos). The feeder consisted of two tubes containing food rewards. In order to attain the reward from a tube, the subject had to remove one or more obstacles. I tested to see if the subject would choose the tube with greatest profitability first. The subject did not discriminate when given a choice between a tube with two obstacles and a tube with three obstacles. The subject also did not discriminate between a tube with larger number of food items and a tube with fewer food items (each tube with one obstacle). However, the subject did discriminate between a tube with reward and a tube without reward. The failure of the subject to discriminate on the basis of number may reflect the low cost associated with making the sub-optimal choice. With some improvements, the feeding apparatus may provide a way to examine spontaneous numerical competence in free-living birds without having to capture subjects.

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Author Institution: Dept. of Biology, Xavier University, OH

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The Ohio Journal of Science, v105, n4 (September, 2005), 97-99.