Mainwaring M.C. (2011) The use of nestboxes by roosting birds during the non-breeding season: a review of the costs and benefits. ARDEA 99 (2): 167-176

The advantages and disadvantages of breeding in nestboxes are well known, whilst the merits of roosting in nestboxes during the non-breeding season remain poorly understood. Here I review the advantages and disadvantages of using nestboxes as roosting sites during the non-breeding season. The main advantage of nestboxes is that they increase the number of cavities available for roosting and birds gain considerable thermal benefits and energy savings, when compared to congeners roosting outside of cavities. However, the main disadvantage is that roosting birds are widely targeted by detrimental ectoparasites, and birds actively avoid nestboxes where ectoparasites are abundant. Meanwhile, there is insufficient evidence to make any firm conclusions as to whether roosting in nestboxes increases or decreases predation risk and this is an area, which warrants further research. Consequently, there is a great deal of variation in the quality of individual nestboxes as roosting sites, and interspecific competition results in larger and more dominant species roosting in preferred nestboxes. In summary, this review emphasises the importance of nestboxes to roosting birds during the non-breeding season.