DIET AND BIOLOGY OF THE LAUGHING OWL SCELOGLAUX-ALBIFACIES (AVES, STRIGIDAE) ON TAKAKA HILL, NELSON, NEW-ZEALAND

The faunal composition of two Holocene fossil deposits of small verteb rates provided new information on the diet and biology of Sceloglaux a lbifacies, a strigid owl endemic to New Zealand. The taxonomic composi tion and several measures of diversity of the prey accumulation are gi ven. Most taxa in the deposit had a mass of 50-150 g, but species up t o 400 g were also present. The owl was a generalist feeder, but the pr ey biomass distribution showed that a few taxa provided most of its en ergy requirements. Changes in the diet appeared to coincide with the a ppearance of Rattus exulans, the Polynesian rat, and the consequent de cline or extinction of several prey. The ecologies of extant taxa repr esented in the deposit suggest that the owl was primarily a nocturnal forest species. Many prey taxa were terrestrial. Species richness was higher for both diurnal (by 50%) and nocturnal (by 63%) vertebrates in the deposit than in the present fauna around the site. Analysis of po ssible guilds in the pre-human and present faunas of Takaka Hill sugge sts that ground-frequenting taxa were most severely affected by extinc tions; three guilds vanished entirely.