One-legged standing (or unipedal posture) in birds was investigated with a particular focus on the role of ambient air temperature on this behaviour in a variety of wading birds and waterfowl. Waterfowl (Anas platyrhynchos and Cygnus atratus) were less likely to be observed standing on 1 leg than long-legged species of wading birds (Ardea novaehollandiae, Limosa lapponica, Platalea regia, Himantopus himantopus), perhaps because of differences in the length of their legs. Feeding behaviour and activities associated with disturbance influenced the frequency of unipedal posture. For captive flamingos (Phoenicopterus roseus) and pied stilts (Himantopus himantopus) the proportion of birds observed standing on 1 leg increased as the temperature increased from 8 to 19C. This observation contradicts the theory that unipedal posture is a behavioural adaptation to minimise heat loss on cold days. An alternative theory based on unihemispheric slow wave sleep (USWS) patterns is proposed as an explanation for unipedal posture and is recommended as a focus for future research. Our results also confirm the importance of considering differences between species in leg anatomy and activity levels to measure the effects of temperature.
There have been few studies on the temporal patterns of social behaviours and how they relate to timing of life history stages in nocturnal colonial bird species. This study focuses on the threatened Westland petrel (Procellaria westlandica; Procellariidae), to investigate temporal patterns in colonial interactions, including vocalisations and social behaviours, in the context of petrel sociality. We conducted extensive behavioural observations on the colony at different time-scales (throughout single nights, between seasons, and across years) to characterise the temporal dynamics of at-colony behaviours. These analyses show consistent temporal variation in several behavioural attributes (e.g., social interactions, vocalisations, eyes closed, body movements), with little or no temporal variation in others (e.g., self maintenance or stationary behaviours). These data provide the basis for specific predictions to test the role of social interactions between temporally varying vocalisations and social behaviours in nocturnal colonial birds.
A total of 730 variable oystercatchers (Haematopus unicolor) were recorded during a survey of the entire 1,500 km coastline of the Marlborough Sounds, New Zealand in spring 2006. This included 347 breeding pairs, 28 single birds and a non-breeding flock of 8 birds. The distribution of oystercatchers was influenced by habitat and human development, with fewer birds found in the inner sounds, where there is most development, and in the exposed outer coastline, where cliff or boulder habitat is limiting. Using similar methods of coastal surveys during the breeding season, the estimated national population of oystercatchers has increased from 2000 birds in 1970-71 to 7000 birds in 2006. This represents a population growth rate of 3.5% per annum. Winter flock counts give lower population estimates and coastal surveys are recommended for future monitoring of this species.
We estimated apparent annual survival of adult and young grey-faced petrels (Pterodroma macroptera gouldi) and age of first return to the natal colony of young birds from 2 colonies in the Bay of Plenty, New Zealand, between 1991 and 2008. We analysed the capture histories of 5844 adult birds and 928 chicks in a mark-recapture framework. The apparent adult annual survival rate was 0.89 after accounting for transience effects, which were greater at the mainland site (Mauao, Mount Maunganui) than on the island colony (Motuotau, Rabbit Island). Annual survival of young birds between fledging and 2 years of age was 0.844 for Mauao and 0.865 for Motuotau. Around 50% of fledglings that returned to their natal colony did so by 4 years of age, and by age 6, the probability of a fledgling returning was approximately 1.0. These are the first reliable estimates of these parameters for grey-faced petrels and are vital for models aimed at predicting the effects of natural perturbations or management interventions on breeding populations.
We report Records Appraisal Committee (RAC) decisions regarding Unusual Bird Reports received between 1 Aug 2008 and 31 Dec 2010. Among the 58 submissions accepted by the RAC are the 1st New Zealand records of streaked shearwater (Calonectris leucomelas) and straw-necked ibis (Threskiornis spinicollis), 2nd records of great shearwater (Puffinus gravis), semipalmated plover (Charadrius semipalmatus) and Franklin’s gull (Larus pipixcan), and 3rd records of little stint (Calidris minuta) and black kite (Milvus migrans). Other notable records included the 1st oriental cuckoo (Cuculus optatus) from the Kermadec Islands, a New Zealand dabchick (Poliocephalus rufopectus) near Nelson, and 2 records of Stewart Island shag (Leucocarbo chalconotus) near Lake Ellesmere, Canterbury.
We investigated the population size and annual survival of Salvin’s albatrosses (Thalassarche salvini) breeding at the Western Chain, The Snares, New Zealand. A count of breeding pairs during incubation resulted in totals of 1100-1200 breeding annually on Toru and Rima Islets in the 3 years 2008-2010; none was seen breeding on Tahi, Rua or Wha Islets. The majority of adults bred annually. Based on banding and recapture the annual survival probability of breeding birds was estimated to be 0.967 while that of known-age birds banded as chicks in Feb 1986 was estimated at 0.939. A bird banded as a chick on the Bounty Is in 1985 was found breeding on Toru Islet of the Western Chain in the 3 years 2008-2010. This is the first record of a banded Salvin’s albatross breeding away from its natal island.