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Why do birds stand on one leg? – A pilot study of exotic and native New Zealand birds

Notornis, 57 (4), 173-177

T.D. Harker; R.F. Harker (2010)

Article Type: Paper

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.

The impact of electrocution on the New Zealand falcon (Falco novaeseelandiae)

Notornis, 57 (2), 71-74

N.C. Fox; C. Wynn (2010)

Article Type: Full article

In a 5 year radiotracking study of 55 falcons on the Wairau Plain, Marlborough, the causes of death in 21 birds were identified. Of these, 10 (47%) falcons were electrocuted (7 juvenile females, 1 adult female, 1 juvenile male, and 1 adult male). Seven of the 10 poles were fitted with transformers. This level of mortality is thought to be too high to sustain a population of falcons. Suggestions are made how to mitigate the problem.

A census of variable oystercatcher (Haematopus unicolor) in the Marlborough Sounds

Notornis, 57 (4), 169-172

M. Bell (2010)

Article Type: Paper

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.

Use of radio telemetry to determine home range and movements of the bellbird (Anthornis melanura) – a feasibility study

Notornis, 57 (2), 63-70

E.B. Spurr; K.M. Borkin; S. Rod (2010)

Article Type: Paper

Radio transmitters were successfully attached to 7 male bellbirds (Anthornis melanura) in Kennedy’s Bush and Cass Peak Reserve, Port Hills, Christchurch, during the breeding season. A hand-held radio receiver was used to re-locate them. In addition, we used a grid of 4 remote continuously-operating proximity sensors (radio receivers connected to data loggers) to measure the home-range size of 1 bellbird (#7). Five of the bellbirds were detected regularly within 60 m of the site where they were captured. The other 2 were always detected at least 100 m away. Two of the 5 regularly detected near their capture location were occasionally detected 400–500 m away, in gullies with flowering flax (Phormium tenax) and kowhai (Sophora microphylla). The full home range (100% MCP) of bellbird #7 was at least 3.7 ha, and its core home range (90% MCP) was at least 0.2 ha. Its night-time roost was near the centre of its home range. First departure from the roost was before sunrise and last arrival about sunset. If used more extensively, radio telemetry would be useful for measuring home ranges and detecting long-range movements of bellbirds.

Seasonal variation in duck populations on the Waihopai River, Invercargill, New Zealand

Notornis, 57 (2), 57-62

J.R. Wood; C.J. Garden (2010)

Article Type: Paper

Seasonal variation in size of duck populations was examined using weekly surveys along a 1.5 km section of the Waihopai River, Invercargill, New Zealand, between Jul 1995 and Jul 1996. Six species were recorded: mallard (Anas platyrhynchos) (n = 8307), New Zealand shoveler (A. variegata) (n = 285), grey duck (A. superciliosa) (n = 36), paradise shelduck (Tadorna variegata) (n = 4), grey teal (A. gracilis) (n = 1), and New Zealand scaup (Aythya novaeseelandiae) (n = 1). Asynchronous seasonal trends were observed for mallard/grey duck and shoveler populations: mallard/grey duck numbers peaked during duck hunting season, whereas New Zealand shoveler peaked just prior, and declined during hunting season. A relatively constant rise in mallard/grey duck from Jan to late Jun highlights the difficulties in distinguishing the relative effects of post-breeding moult congregations vs. dispersal to refugia from hunting–related disturbance.
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