<p>The hazel dormouse is currently in steep decline within the UK and other parts of northwest Europe, with one cause being the limited availability of nesting locations following historical deforestation. Nest boxes are often used as a conservation tool to mitigate the lack of natural opportunities, but until recently only one model of dormouse box was commonly used; this ‘conventional’ box is similar to a reversed bird nest box with an entry-hole facing the tree stem. However, in 2013 the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire designed a new model with a more restricted entry from underneath to deter bird competitors; this was anecdotally reported to perform better for dormouse. The performance of these two boxes was compared by randomly locating boxes of each model across one site and then monitoring uptake after two to five years. Hazel dormice showed a strong preference for the Brampton box. No birds were found to successfully use the Brampton box, and the lack of competition with birds and/or reduced ectoparasite loads from previous bird nesting activity may be significant factors in the selection of this box. However, when conventional boxes that had previously been occupied by birds were omitted from the paired study, hazel dormouse still showed a significant preference for the Brampton box which indicates that other factors are also involved; these may include superior insulatory properties of the Brampton box, two entrances rather than one offering better security from predators, or the different ages of the two different box types in this study affecting ectoparasite loads.</p>