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

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.