Habitat use by yellowheads, mohoua ochrocephala (Aves: Muscicapidae), in the hawdon river valley, arthur’s pass national park. 2. time budgets and foraging behaviour

Instantaneous sampling was used to describe the ecological niche of yellowheads. Observations began during nesting in 1983 and continued until April 1984. Yellowheads spent on average 90% of their time foraging. As daylength decreased, an increasing proportion of time was spent foraging and a decreasing proportion of time was spent on social activities. When feeding nestlings, females spent significantly more time foraging than did males. Yellowheads spent 75% of their time in the upper understorey and the shaded canopy. There was no difference in the relative use of strata in the two canopy tree species, nor a sexual difference in the time spent in each strata. Yellowheads were entirely insectivorous. Prey items were recorded on 33 occasions; most were lepidopteran larvae. The most common foraging method was surface gleaning, mostoften on foliage and trunks. Time spent foraging on different substrates varied with tree diameter and tree species. Relative use of different foraging methods changed during the study, as did the types of substrates searched for prey and the proportion of time spent in different strata and at different heights in the forest. Presumably these changes were in response to variations in invertebrate availability.