Nest-box choice in the laboratory mouse: Preferences for nest-boxes differing in design (size and/or shape) and...

The purpose of this paper is to introduce two experimental paradigms used for a laboratory approach to spatial choice behaviour in the mouse. The experimental procedure involves a free-choice spatial situation which allows the development of a long-term behavioural process. The animal is placed in an arena containing two or more nest-boxes to be chosen as nest-sites. These may differ in certain characteristics, such as size, shape, or composition. The experimental procedures are: (1) a series of independent successive choice tests, or "paired comparisons"; (2) a dependent successive choice test, or "forced progressive elimination ranking". Both procedures have been used to study nest-box choice in mice according to spatial parameters. In Experiment I, "paired comparisons" were used to evaluate the strength of individual preferences for nest-boxes differing in design (size and/or shape), according to whether nest-boxes were open or closed. In Experiment II, the second method was used to analyse individual preferential ranking patterns with series of nest-boxes differing in design or composition. The results of the two types of experiment were complementary regarding the design (size and shape) of the nest-boxes: highest in order of preference were small narrow-sided nest-boxes, followed by small square ones, then the small circular one, and last the big circular ones. Experiment I proved in particular the role of closure in reinforcing the strength of preferences. In Experiment II, on the other hand, the constituent materials did not appear to have any clear influence on preferential ranking patterns for the nest-boxes differing in design; nevertheless, a positive correlation was noted between the classification of objects made of different materials, and the degree of darkness afforded by these materials.