Patterson-Kane, E. G. 2003. Shelter enrichment for rats. Contemporary Topics in Laboratory Animal Science 42(2), 46-48.

Nest boxes are a simple and effective form of environmentalenrichment. Rats accept a wide range of nest-box types but have the strongest...preference for enclosed, opaque, thermoplastic boxes. ...Tubes have proven a relatively ineffective enrichment for rats. ... Nesting paper may substitute for nest boxes to some extend, but nest boxes are preferred to nesting paper when the two are offered separately. [p. 46] ....All rats in standard laboratory caging should be provided with a nest box. This proviso should be considered a minimum husbandry requirement rather than a benevolent enrichment. As rat nest boxes are not commercially available at this time, laboratories should consider constructing their own, using the simple designs presented in this study. [p.47-48]