Publications Archive

The South Island saddleback (Philesturnus carunculatus carunculatus) is one of two subspecies of the New Zealand saddleback. Despite the endangered status of this subspecies, it was not studied in detail until 1994, when 26 birds were released onto Motuara Island in the Marlborough Sounds of New Zealand. I report the foraging behaviour and diet of this reintroduced population during the first breeding season after release. South Island saddlebacks used their bills in a variety of ways when foraging, and were predominantly insectivorous. They obtained most food from the ground and five-finger (Pseudopanax arboreus), and the number of prey captured generally reflected the amount of time saddlebacks spent on foraging substrates. North and South Island saddlebacks are very similar in terms of foraging behaviour, prey handling techniques and types of invertebrate prey consumed. The foraging patterns and diet of South Island saddlebacks on Motuara Island differed from all potential competitors. I conclude that the success of the South Island saddleback transfer to Motuara Island should not be threatened by a lack of food or foraging opportunities.

During the 1997/98 breeding season we counted the breeding populations of Chatham Island shag (Leucocarbo onslowi), Pitt Island shag (Stictocarbo featherstoni) and black shag (Phalacrocorax carbo). Surveys, on foot or from kayaks and fishing boats, of all potential shag nesting habitat within the Chatham Islands provided the first complete census for shags breeding there. The breeding population of Chatham Island shag was 842 pairs in 10 discrete colonies, while there were 729 breeding pairs of Pitt Island shag at 63 locations throughout the group. Given that the counts of the endemic shags are for the total world populations. these species are extremely rare. The black shag breeding population was 233 pairs, in 5 locations on Chatham Island only. Comparisons with counts made during the 1960s and 1970s by visiting ornithologists suggest that the populations of Chatham Island shag and black shag have remained relatively stable, although the distribution of colonies of both species has changed significantly. Too few previous counts of Pin Island shag colonies were available to determine a population trend. All 3 species are threatened in the Chatham Islands by destruction of nesting habitat, disturbance of nesting colonies, human persecution, and predation by introduced mammals.

The presence of small numbers of Westland petrels (Procellaria westlandica) off the east and west coasts of South America is a relatively recent discovery. Evidence for the presence of the species in those seas has, however, been found to extend back at least as far as 1913, with the re-identification of a specimen in the American Museum of Natural History collection as P. westlandica. Preliminary comments are given on the condition of plumage of Westland petrels observed in South American waters.

The breeding of little shags at the Lindale Tourist Complex, Wellington, was studied during the 1997/98 and 1998/99 seasons. Breeding at the site first occurred in spring 1993 when a single pair was present. By 1999, the breeding population had increased to about 44 pairs. The breeding season extended over eight months (August to March), with a successful breeding cycle taking about 11 weeks (courtship and nest-building one week, incubation four weeks, chick rearing six weeks). Breeding success was high, with 79% of nesting attempts resulting in young leaving the nest. The productivity of successful nesting attempts differed significantly between the two seasons; 1.5 young per nest in 1997/98 and 2.1 in 1998/99.

Four historical records of snipe from Campbell Island in the New Zealand subantarctic are reviewed to determine whether any may refer to the recently discovered Campbell Island snipe (Coenocorypha sp.). It is concluded that none of the records is likely to have been Campbell Island snipe, and that Norway rats (Rattus norvegicus) probably reached Campbell Island before 1840. An 1840 record of “a Scolopax” may have been Coenocorypha, but this is not supported by any documentation or specimen. All other records were errors in identification referring to bar-tailed godwits (Limosa lapponica), or incorrect recording of the location where snipe were seen. Three “snipe” specimens shot on Campbell Island in 1894 were located in the Museum of Victoria and are bar-tailed godwits.

Breeding of South Island pied oystercatchers (Haematopus ostralegus finschi) on farmland in mid-Canterbury was studied from 1987 to 1997. Each year birds returned to breeding territories from early June; females arrived about six days earlier than males. Laying dates extended from early August to mid-November and were similar in all years. Most first clutches were laid from late August to mid-September. Up to two replacement clutches were laid. Clutch size averaged 2.29 (range 1-3 eggs) and declined through the breeding season, but was consistent from year to year. Mean first clutch sizes were larger than replacement clutches. On average, 47% of eggs hatched and 59% of these chicks survived to fledge. Both hatching and fledging rates declined through the season. On average, 52% of pairs which laid in any year failed to rear a fledgling. Hatching success was greater in cultivated sites than pasture sites, but fledging success was similar at both sites. Trampling by stock, farming activities, and unknown causes were the main causes of egg loss. Sagar, P.M.; Geddes, D.; Banks, J.; Howden, P. 2000. Breeding of South Island pied oystercatchers (Haematopus ostralegus finschi) on farmland in mid-Canterbury, New Zealand. Notornis 47 (2): 71-81. Keywords breeding success; Haematopodidae; agricultural land; land use; population change