A new approach to excluding small nocturnal predators from nest boxes

Date: 23, Dec, 2019
Author(s):   D. Stojanovic, S. Eyles, H. Cook, F. Alves, M. Webb & R. Heinsohn
Publisher: TSR Hub

Many species nest mainly or exclusively in tree cavities. However, tree cavities can be scarce and access to them competitive, and in some habitats deforestation has exacerbated the shortages. Nest boxes have consequently become an important conservation tool where breeding is limited by a lack of tree hollows. However, in addition to a scarcity of tree hollows for breeding, some threatened species are also severely impacted by predation while they are in their nests. This is a significant problem for the Critically Endangered swift parrot which is seriously threatened by sugar gliders. The sugar glider is a small (~120g) possum introduced to Tasmania in the 19th century. It is a major predator on small, cavity-dependent birds. As sugar gliders are of a similar size to the birds they can fit through the nest box openings. The scarcity of tree hollows is also bringing sugar gliders and nesting birds into contact more often. There is consequently an urgent conservation need to protect birds in nest boxes from sugar gliders. To address this challenge, we have developed and trialled an automated, solar-powered door that can be attached to nest boxes for at least the duration of a three-month breeding season. A photosensitive trigger mechanism opens the door at dawn and closes it at dusk to prevent nocturnal predation. We opted for a light sensor rather than a clock because the days may range in length over the course of the three-month breeding season, especially at high latitudes. This device became known as a “possum-keeper-outterer” during fundraising activity (crowdfunding campaign ‘Operation PKO’), as sugar gliders are key predators of threatened birds in our study sites in south-eastern Tasmania, and we refer to it hereafter as the PKO.

2.2.2 Nest Box Predation Findings Factsheet V3