Publications Archive

The diet of black shags (Phalacrocorax carbo) at Pencarrow, New Zealand, during April – October 1999 is described from otoliths, jawbones and pharyngeal tooth plates found in 119 regurgitated pellets of adults and four stomachs and two regurgitations of chicks. Black shags were primarily marine foragers, with only one freshwater item, crayfish (Paranephrops planifrons) among 420 food items identified. Half of the diet comprised spotty (Notolabrus celidotus), but in total, 22 species were found in the pellets, including 17 fish species. The size of fish otoliths indicated significant differences in the length of the 11 most frequently occurring fish species. These ranged from an estimated length of 106 mm to 275 mm (mean length 220 mm) and were similar to those reported from other NZ studies. The mean length of fish taken by adults in winter was smaller compared with those in autumn and spring.

Stephens Island provides the classic example in the New Zealand region of the effect that predation by feral cats (Felis catus) can have on an island land bird fauna. Twenty-five species of native New Zealand land birds were recorded on the island in the early 1890s when it was still forested and free of mammalian predators. It is probable that Stephens Island still had its original land bird fauna at that time. The land bird species included large populations of the extinct Stephens Island piopio (Turnagra capensis minor), and the endangered South Island saddleback (Philesturnus c. carunculatus). Cats were introduced to Stephens Island, probably in 1894. They soon became feral and multiplied rapidly. The evidence indicates that cats were responsible for the rapid demise of the native land bird fauna of the island.

Birds recorded on the Kermadec Islands, south-west Pacific, between 1967 and 1998 are summarised. Population estimates and distributions are given for the 24 breeding species. Brown noddy (Anous stolidus) is recorded breeding there for the first time. Information on breeding chronology for most breeding species is presented. Sightings of 53 non-breeding and vagrant species are summarised; 24 of these were new records since the last comprehensive review was published in 1970. The total bird list for the Kermadec Islands is now 80 species, including records of giant petrels (Macronectes), frigatebirds (Fregata) and oystercatchers (Haematopus) not identified to species. A further 16 species are included in a suspense list. The Kermadec Islands have only seven indigenous land birds, but retain a diverse seabird fauna, very similar to those of Norfolk and Lord Howe Islands. The land birds and seabirds of the largest island (Raoul) have been decimated by introduced cats (Felis catus) and rats (Rattus exulans, R. norvegicus). Introduced goats (Capra hircus) (since eradicated) drastically modified the vegetation of Raoul and Macauley Islands, and this also affected some bird species. Recommendations for restoration of the avifauna of these two islands are given.

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.