Diet and biology of the laughing owl Sceloglaux albifacies (Aves: Strigidae) on Takaka Hill, Nelson, New Zealand

Abstract

The faunal composition of two Holocene fossil deposits of small vertebrates provided new information on the diet and biology of Sceloglaux albifacies, a strigid owl endemic to New Zealand. The taxonomic composition and several measures of diversity of the prey accumulation are given. Most taxa in the deposit had a mass of 50‐150g, but species up to 400g were also present. The owl was a generalist feeder, but the prey biomass distribution showed that a few taxa provided most of its energy requirements. Changes in the diet appeared to coincide with the appearance of Rattus exulans, the Polynesian rat, and the consequent decline or extinction of several prey. The ecologies of extant taxa represented 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 possible guilds in the pre‐human and present faunas of Takaka Hill suggests that ground‐frequenting taxa were most severely affected by extinctions; three guilds vanished entirely.