The breeding biology of kakerori, or Rarotonga flycatcher (Pomarea dimidiata) was studied during ten years (1987-97) of experimental management aimed at saving this endangered monarch flycatcher from extinction. Kakerori remained territorial all year and were usually monogamous. Most birds kept the same mate from year to year, but pairs that failed to raise any young were more likely to divorce than successful pairs. Despite living in the tropics, kakerori breeding was strictly seasonal, with eggs laid from early October to mid-February, and mostly in late October and early November. Nesting started earlier in years when October was very sunny. Most pairs (74%) laid only one clutch, but some pairs laid up to four replacement clutches when nests failed. Three pairs (1%) successfully raised two broods in a season. Rat (Rattus spp.) predation was the principal cause of nest failure, especially of nests in pua (Fagraea berteriana), the main fruiting tree used by rats during the kakerori breeding season. Annual breeding productivity was initially poor (0.46 fledglings per breeding pair over two years) and the population was declining, but intensive management since 1989 has led to a great increase in productivity (1.07 fledglings per breeding pair over eight years) and the number of kakerori has increased from 29 birds in 1989 to a minimum of 153 birds in 1997. Their IUCN conservation status can therefore be lowered from ‘critically endangered’ to ‘endangered’.
Weka (Gallirallus australis) can be aged accurately up until 50 days old using leg and bill measurements, and then less accurately up to 180 days old using plumage development, wing spur shape and iris colour. Weka less than one year old can be distinguished by their remex tip and wing spur shape. Beyond one year, weka can only be placed into age groups, using wing spur shape.
Osteological characters distinguishing the South Georgian diving petrel (Pelecanoides georgicus) from the common diving petrel (P. urinatrix) are described. P. georgicus is shown to be the main diving petrel in Holocene fossil deposits at Mason Bay, Stewart Island, New Zealand, where it is represented by thousands of bones. P. georgicus is also recorded from dune deposits on Chatham Island. The Codfish Island population is thus a remnant of a formerly large Pacific population that bred on Macquarie Island, Auckland Islands, Stewart Island and Chatham Island, and is therefore of high conservation priority.
The North Island weka (Gallirallus australis greyi) population at Parekura Bay was monitored in 1991-95, during a long dry El Niño event. Adult weka had declined from ~400, in February 1987 (Beauchamp 1988), to 47-63 Weka in Parekura Bay and Whangamumu areas in June 1991. By March 1995 there were only three weka left there. Enhanced production of young weka was insufficient to prevent decline. Known mortality factors were road kills, Timms traps and dogs and stoats. Throughout the study the population lacked females. A “crowing call” by males was identified as associated with mate loss and mate finding.
We examined digestive tract contents and stable nitrogen isotope ratios (δ15N) in breast muscles of Buller’s shearwaters (Puffinus bulleri) salvaged from squid and large-mesh driftnets in the central North Pacific Ocean. The epipelagic Pacific saury (Cololabis saira) was the predominant prey, making up 71% of prey mass in digestive tracts. The remainder of the diet included small numbers of crustaceans, small fishes, and squids. The high degree of specialization in the diet seems to indicate that in the North Pacific, Buller’s shearwaters usually feed at or near the water surface and rarely pursue food under water. Although these birds have been observed feeding on scraps from fishing vessels, our data suggest that offal comprises less than 10 percent of the diet. Stable nitrogen isotope values provided quantified information on the timing of arrival of migrants into the North Pacific.
A breeding male Chatham Island taiko (Pterodroma magentae) was found recently dead of injuries by its burrow on 14 November 1996. Intraspecific fighting followed by sepsis of wounds seems the likely cause of death. All parts were preserved. Food items of taiko include four squid species and one fish species. Its intestinal structure suggests a close relationship with the P. mollis group and P. macroptera. Measurements of bones indicate that most subfossil bones previously referred to this species were correctly identified.
Large breeding colonies of sooty shearwaters or titi (Puffinus griseus) occur on offshore islands around New Zealand and several smaller colonies occur on headlands and near-shore islands around southern New Zealand; their population trends are unknown. Twelve mainland colonies around Otago had between 11 and 620 burrows in the 1992/93 breeding season. The largest of three near-shore island colonies in Otago had at least 1,050 burrows. Sooty shearwater burrows have been recorded from 39 mainland sites in the South Island, but only 11 (28%) of these have been checked in the last 40 years: many may now be extinct. OSNZ Beach Patrol data suggest that the overall number of sooty shearwaters has changed little over a 26 year period. Methods for monitoring sooty shearwater colonies need to be standardised to evaluate population trends in the future.