Jessica Lecours
Project
Sex difference in spatial cognition across spatial scales in brood-parasitic brown-headed cowbirds (Molothrus ater)My proposed research will use cognitive performance testing over spatial scales to explore the sex difference in cowbird reference memory with focus on allocentric tasks related to navigation. Objective and hypotheses: The objective of my research is to determine whether the observed trend in allocentric spatial memory task performance between sexes is apparent in a more ecologically relevant spatial scale. I hypothesize that using a larger scale spatial field for testing will elicit a display of stronger cognitive ability in female birds as it more closely resembles their nest locating and prospecting behaviour. I predict that females will outperform males in both testing conditions (small and large arenas), with a greater effect seen in the larger scale spatial test. Methodology: 30 male and 30 female adult cowbirds (divided into cohorts A and B) will be used in cognitive spatial testing. All have been wild caught near Wilfrid Laurier University and trained to interact with flip-lid reward cups. Two types of spatial cognition tasks will be used. A 5x5 cup array (paired with a 5x5 colored cup array as a control) and an 8-cup radial arm maze, which use baited reward cups to motivate both sexes to perform tasks. Each cohort will be divided in half (15 in each group) and the order of trials will be counterbalanced between large (350 cm x 350 cm) and small (200 cm x 200 cm) arenas, as well as between 5x5 array and radial arm maze tasks. During trials in the small arena, it will be placed within the large arena, and all landmarks will be visible from within both. For the standard 5x5 cup array, a single reward cup in a consistent geometric location will be the point of interest. In the paired color test, each cup will be a unique color, and the reward cup will remain the same color in a randomized geometric location in the array. For the radial arm maze, a single reward cup will remain in a consistent geometric location in an array of 8 cups separated by dividers, and the bird will be disoriented using a turntable prior to performing the task. Significance: Research into the cognitive differences existing between sexes in cowbirds has seen significant results providing evidence for an adaptive evolutionary origin of their differing brain morphology and physiology. This research aims to contribute ecologically relevant evidence to begin to understand how evolution has contributed to the ecology of these birds.
