Burn, C. C., Popat, R. 2021. A tunnel is not enough: Mice benefit from in-cage provision of a communal shelter as well as a handling tunnel. Animal Technology and Welfare 20(3), 203-210.

Mouse shelters can provide mice with security, help them thermoregulate, offer darkness to prevent damage to their eyes and enable climbing and gnawing opportunities. For laboratory mice, there is a vast array of commercially available cage furniture, so choosing which shelter to provide can be difficult. We investigated whether an in-cage handling tunnel alone is sufficient as a shelter or whether an additional cardboard tube or igloo shelter is beneficial. Using 12 cages of adult C57BL/6 mice (5 x female, 7 x male), we conducted a repeated measures experiment, providing the handling tunnel alone or with a cardboard tube or with an amber dome in a randomised order for one week per cage. Cages also contained bedding, nesting material and a gnawing block. We observed that, compared with a handling tube alone, mice with the additional dome sheltered three times more (P<0.001), probably because the dome enabled more mice to simultaneously shelter. The dome significantly reduced time spent using nesting material (P<0.001), so it may have partially substituted for nesting. Some mice used the cardboard tube less than expected by chance, implying that it reduced the useable space available to mice. When the cage was opened for handling, mice with a dome were less likely to spontaneously enter the handling tunnel (P<0.001), so the dome needed briefly removing before tunnel-handling mice. The handling tunnel was not sufficient as a shelter, and a shelter large enough for several mice to occupy it simultaneously should be additionally provided.