This paper describes the activity of garden, bush and riverine birds in the Western Hutt hills, 1981-92. The area is 15 km north of Wellington, 7 km north of the Hutt River estuary, and 15 km south of Pauatahanui Inlet, Porirua Harbour, on the southwest coast of the North Island. Observation is based on 35 years’ residence and >12 500 10-min counts conducted between 1981 and 1992. Species first seen each day are distinguished from those first heard. Whenever possible the birds’ food was recorded. The western hills have fewer native passerines than similar habitat on the eastern hills. Several species increased or decreased during the study. Some apparent decline was attributed to the author’s hearing loss. Wind reduced bird detection. Nectar of New Zealand flax (Phormium spp.) was eaten by silvereyes (Zosterops lateralis), tui (Prosthemadera novaeseelandiae) and starlings (Sturnus vulgaris) at different times. In the study area there were about 0.9 cats (Felis catus) per household, a potential predator on birds.
We investigated the use of call count surveys to monitor weka numbers for management purposes. A Generalised Linear Model based on data from 11 1 nights of listening for weka at Rakauroa (North Island, New Zealand) showed that the number of calls recorded was influenced by listening site and month, but not by wind direction, wind strength, cloud cover, phase of the moon, rainfall or temperature. Mean number of calls heard was highest between December and March, with a peak in January. More birds were heard from certain listening sites. Although there was no correlation between any of the environmental variables and weka calling, wind, and rain may have reduced the audibility of weka in other studies. The estimated probability of detecting weka was 60-80% (mean = 728). At least 3 nights at each listening station were necessary to improve the census accuracy. Call counts of weka at Rakauroa between 1993 and 1997 showed a decline in the number of weka.
The total population of North Island weka (Gallirallus australis greyi) is about 4150 adults spread over five islands, one North Island population, and a number of captive birds in aviaries and mainland island programmes. Between 77% and 84% of the adult weka population are on Kawau Island. Density changes in the Mansion House Historic Reserve, and anecdotal records suggest that adult weka populations on Kawau Island has fluctuated between c.2100 and c.5000 during 1992-1999. The largest declines occurred within 12 months of the 1990-91 and 1997-98 droughts.
The growth of New Zealand’s second mainland Australasian gannet (Morus serrator) colony at Muriwai, north west Auckland is described from counts between 1975 and 1998. The colonies on Motutara Island, and the southern and northern colonies on Otakamiro Point have increased from 28 pairs in 1975 to 1393 pairs in 1998. The potential for future colony expansion on the northern cliff face, where human disturbance is highest, is discussed.
We observed that South Polar Skuas (Catharacta maccormicki) breeding near the Adelie Penguin (Pygoscelis adeliae) western colony at Cape Crozier, Ross Island, Antarctica were able to forage throughout the colony, the majority of which was not defended by territorial skuas as in other Ross Island colonies. All local skuas were able to find enough food on the colony throughout January to support breeding and none were seen to forage at sea. Skuas foraged as individuals to obtain penguin eggs and chicks but kleptoparasitism usually occurred so that several skuas fed in turn on a single carcass. At the end of each feeding event a general melee occurred in which up to 30 skuas fought over the chick remains. The implications for skua breeding of this foraging regime, in which any skuas in the local area can obtain penguin food, are considered. We suggest that the high levels of food availability contributed to the unusually high success for this region of these skuas in raising both chicks. Desertion of chicks while foraging, however, leads to some mortality among older chicks later in the season through predation. It is recommended that further research on skuas at super-large penguin colonies be undertaken.