Common waxbills use carnivore scat to reduce the risk of nest predation

For many animals, nest construction is a prerequisite for successful breeding. The choice of nesting materials is an important component of nest construction, because material properties can influence nest design and, potentially, reproductive success. Common waxbills are small African finches that select carnivore scat as a material to include in, on, and around their nests. I investigated the hypothesis that scat functions to reduce predation risk by documenting its use in a wild population of common waxbills and by conducting an artificial nest experiment. Among natural nests, scat was present in every nest that hatched young, and parents continued to add scat to nests throughout the nestling period. Among artificial nests, those that received experimental additions of carnivore scat survived at a significantly higher rate than did untreated nests, suggesting that scat functions to reduce predation risk. The mechanism by which nests are protected remains unclear, although it is likely that scat acts as an olfactory deterrent and/or camouflage. Researchers have long focused on the implications of nest site characteristics for avian life-history evolution. Results of the present study suggest that nest materials, similar to nest sites, may influence life histories of nest-building animals by affecting predation risk. Copyright 2005.