Of nest-box monitors who responded, 86 percent used some form of predator deterrence (Figure 3). Their methods ranged from the conventional, to the creative, to the downright extraordinary. The Noel Guard - a wire mesh tube attached to the front of the nest box to prevent raccoons and cats from reaching into the entrance hole - was the most commonly used method (44 percent). Participants also used conical guards (10 percent) and PVC stovepipe/baffles (6 percent), both of which prevent predators from climbing the nest-box pole. Three percent of respondents greased the pole or pipe, making it slippery for animals such as raccoons and squirrels to climb. Other methods (23 percent) included, in the majority of cases, devices used to extend the outside length of the entrance hole to prevent animals from reaching into a nest box. Some monitors took added measures such as surrounding boxes with poultry netting, spikes, and even barbed wire. One participant wrote, "This box is mounted on an electric fence - nothing bothers this one."

Figure 3. Predator deterrence methods used by The Birdhouse Network participants in 2001.