Galagos as avian nest predators in South Africa

Galagos are generally regarded as dietary specialists that feed predominantly on insects and gum. The diet of the thick-tailed greater galago is more varied and also includes fruit and small vertebrates, although the latter is rare and restricted to certain populations. The southern lesser galago is seemingly a more specialist forager, but frugivory was recently reported in two separate populations, suggesting at least some dietary plasticity in this species. The species is not known to consume vertebrates. Here I report on observations of avian nest predation by both thick-tailed greater and southern lesser galagos in Roodewal State Forest Reserve in South Africa. Galagos were responsible for 56 % of nest losses captured on trail cameras. Both species consumed eggs and nestlings of six species of passerines ranging in size from recently hatched to ~30 g nestlings almost ready to fledge. The consumption of vertebrates by the southern lesser galago represents an extension of its diet, as this has not been reported before. The results suggest that eggs and nestlings comprise part of the regular diet of thick-tailed greater galagos in the study area, albeit only seasonal. The consumption of vertebrate prey by southern lesser galagos may represent the expression of latent behavior which is only expressed under certain environmental conditions, e.g., a severe drought, when its regular food base may be diminished.