variation

Possum leaf diet from 1976 to 1989 in the Orongorongo Valley was compared with the diet recorded from four previous years, using faecal analysis. There were large differences in the proportions of species eaten in different seasons and between different years. There was little overall change in the proportion of the main diet tree species, Metrosideros robusta and Weinmannia racemosa, and seasonal increases or declines in one were usually balanced by opposite changes in the other.

Vocalisations are important for territorial defence, mate attraction, and species recognition in many songbirds. Comparative studies on the songs of birds between islands and mainland populations provide insight into the evolution of vocal communication in terms of both ecological and social factors. We compared the vocalisations of tui (Prosthemadera novaeseelandiae novaeseelandiae), an endemic honeyeater from New Zealand’s mainland, with those of a subspecies from the remote Chatham Islands (P. n. chathamensis).