Individual study: Modifications can prevent raccoons Procyon lotor from entering wood duck Aix sponsa nest boxes
Eaton R.L. (1966) Protecting metal wood duck houses from raccoons. The Journal of Wildlife Management, 30, 428-430
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Use artificial nests that discourage predation
A trial in captivity in Illinois, USA, in the 1960s (Eaton 1966) found that raccoons Procyon lotor could enter metal wood duck Aix sponsa houses (cylindrical metal houses with a 33 cm cone on top and a 10 cm circular entrance hole) more easily if the cone on top of the house was increased beyond the standard 33 cm. However, if the cone was extended to provide a 7.6 cm overhanging roof and the distance between entrance hole and the roof was increased from 30 to 60 cm, then none of the five raccoons tested could access the nest hole. Reducing the size of the entrance hole to 8.9 x 7 cm also prevented all raccoons from entering, but the authors warn that it is not certain whether wood ducks would use such entrances.