Do nest boxes in restored woodlands promote the conservation of hollow-dependent fauna?

Vegetation restoration is considered as an important strategy for reversing biodiversity decline in agricultural areas. However, revegetated areas often lack key vegetation attributes like large old hollow-bearing trees. As these trees take a long time to develop, artificial cavities such as nest boxes are sometimes provided to address lag effects. We conducted a 3-year experiment using 150 nest boxes with 4 designs to quantify patterns of occupancy within 16 replanted areas and 14 patches of remnant old-growth eucalypt woodland. We quantified patterns of occupancy of nest boxes in physically connected versus isolated remnants and plantings, and multiple covariate effects on nest box occupancy at the nest box, tree, patch, and landscape levels. Our analyses revealed a lower probability of nest box occupancy within remnants (vs. plantings) for 2 of the 6 response variables examined: any species and the Feral Honeybee. Nest boxes in connected remnants and plantings were more likely to be occupied than those in isolated plantings and remnants by any mammal and the Common Brushtail Possum. Nest boxes in restored woodlands are used by some hollow-dependent fauna but principally already common species and not taxa of conservation concern. Nest boxes were also used by pest species. A key management consideration must be to create connected habitat to facilitate colonization of nest boxes by mammals. Approximately 15% of the cavity-dependent vertebrates within the study area used next boxes, possibly because the diverse requirements of the array of other species were not met by the range of nest boxes deployed.