Five-minute bird counts in Pureora Forest Park were compared between one site in a 1978-81 study and two similar sites in a 1997-98 study. The two sites from the more recent study have had different levels of pest control since the historical survey. The mean number of birds detected per count was calculated for each species and the differences among the sites were tested for significance. The results suggest a dramatic decline over time (irrespective of pest control) in many small native insectivores, including the grey warbler (Gerygone igata), tomtit (Petroica macrocephala ), fantail (Rhipidura fuliginosa) and rifleman (Acanthisitta chloris). A large increase in bellbird (Anthornis melanura) conspicuousness was detected. Increases were observed for robin (Petroica australis), kokako (Callaeas cinerea wilsoni), kaka (Nestor meridionalis), parakeet (Cyanoramphus novaezelandiae) and kereru (NZ pigeon Hemiphaga novaeseelandiae) between the historical site and the recent pest-controlled site, but tui (Prosthemadera novaeseelandiae) counts have decreased. The number of species with higher mean counts in the site with more intensive pest treatment suggests that pest control has had a positive effect on some bird populations. However, some species also increased at the site with less-intensive treatment, and tui is more conspicuous at this site than the controlled one. The study shows the value of historical bird count surveys for assessing long-term changes in bird populations, and suggests a need to make similar data sets from around New Zealand more readily available to researchers.
A previously unknown Moriori-based account of the extinct Hawkins’ rail (Diaphorapteryx hawkinsi) from the Chatham Islands is presented and discussed. The account, recorded by Sigvard Jacob Dannefaerd in a letter to Lord Lionel Walter Rothschild in 1895, includes details of the species’ appearance, behaviour and Moriori hunting methods. A second, similar description of a previously unidentified Chatham Islands bird is also linked to Hawkins’ rail. The clarity of the accounts suggests a considerably later extinction date for the species than previously supposed.
The diet of blue penguins (Eudyptula minor) at Oamaru, New Zealand was examined by stomach flushing. The 22 species identified comprised 14 fishes, 1 cephalopod and 7 crustaceans. Slender sprat (Sprattus antipodum) accounted for more than half of the diet throughout most of the year while Graham’s gudgeon (Grahamichthys radiata) and arrow squid (Nototodarus sloanii) were also important seasonally. Prey were either small, schooling, nearshore species or pelagic juveniles of larger species.
Status, breeding, and foraging of Chatham Island tui (Prosthemadera novaeseelandiae chathamensis) were studied on Rangatira Island, Chatham Islands between January 1995 and May 1999, with short visits made to adjacent Pitt Island throughout this period. The total population was estimated at ≈260 adults. Most birds were resident on Rangatira Island in spring, summer and autumn but moved to Pitt Island during the winter. In spring birds commuted between the two islands but became resident on Rangatira when breeding commenced. Radio transmitters were attached to adult tui to monitor breeding. No radio-tagged females bred (n = 13) but at least two of three radio-tagged males raised young. Adult tui were intolerant of disturbance during nesting so estimation of productivity was made by mapping the number of fledgling groups. Flax (Phormium tenax) nectar appeared to be the most important food for breeding tui and birds travelled long distances to visit flowering plants. Fruits of ngaio (Myoporum laetum), matipo (Myrsine chathamica), karamu (Coprosma chathamica), mahoe (Melicytus chathamicus) and muehlenbeckia (Muehlenbeckia australis) were also important foods. Invertebrates were most important when females were feeding their young. The amount of breeding that occurred each season was directly related to the abundance of flax flowers in spring, and in good flax flowering years tui were able to rear two broods. In poor flax flowering years many birds did not breed. Control of feral cats on Pitt Island would most likely result in a significant increase in this breeding population; however planting of flax adjacent to the forest areas on Chatham Island along with predator control may be necessary before tui can re-establish there.