Bird nests often contain objects produced and manipulated by other animals, including human rubbish. The function, if any, of these items remains unclear, and it is unknown whether they might serve a signalling role to increase the conspicuousness of the nest lining or contribute to its crypsis. We located several nests of the introduced song thrush (Turdus philomelos) in New Zealand containing discarded cigarette butts. These items were embedded into the dried mud-matrix of the nest and appeared visually inconspicuous to the human observer. However, human and avian visual sensitivities are dramatically different. We used full-spectrum reflectance spectrophotometry, combined with perceptual modelling of the avian visual system to assess the contrast between mud lining, garbage, and the colours of thrush eggs. Our analyses confirmed that, when perceived by birds, cigarette butts were similar in appearance to the nest lining and showed sharp contrast with the eggs. We suggest that cigarette butts form an opportunistic structural component of the song thrush nest. It remains to be determined whether human-made objects in song thrush nests serve anti-predator or an olfactory signalling function. This study illustrates the application of avian perceptual modelling to test signalling based hypotheses for the extended phenotype of birds, including nest architecture.
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.
A pair of barn owls (Tyto alba) was found breeding in Kaitaia farmland in Apr 2008, and observations on their nesting biology and behaviour were made over a period of 24 months. Another injured young barn owl, possibly from an earlier breeding attempt, was found with the pair at the time of their discovery, and brought into captivity. The nest tree was climbed and 2 dead owlets recovered, but the pair re-nested and 3 young successfully fledged. Pellets and prey remains were collected and their diet is described through pellet analysis. This is the 1st record of wild barn owls breeding in New Zealand.
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.
A new subspecies of Coenocorypha snipe from Campbell I is described and named. This bird was discovered on rat-free 19 ha Jacquemart I in 1997, and had probably been confined there as a breeding species for about 170 years. Norway rats (Rattus norvegicus) were eradicated from 11,268 ha Campbell I in 2001, and snipe soon began to recolonise the main island from Jacquemart I 1 km offshore. Twelve adults and 5 chicks were caught on Campbell I in Jan 2006, and 1 nest was found. Genetic analysis of blood samples, and measurements and plumage descriptions from these birds revealed that they were best regarded as a subspecies of Coenocorypha aucklandica, a species here recognised as confined to the subantarctic Auckland, Antipodes and Campbell Is, and specifically distinct from the 2 other extant Coenocorypha snipes (Snares I snipe C. huegeli and Chatham I snipe C. pusilla).
Few places have been as ecologically devastated by the introduction of exotic mammals as Phillip Island in the Norfolk Island group. Pigs (Sus scrofa), goats (Capra hircus) and rabbits (Oryctolagus cuniculus) denuded the island so severely that massive amounts of soil and underlying substrate were lost through erosion. Rabbits, the last of these exotic animals to be removed, were eradicated during the 1980’s. Since then the extent of vegetation on the island has been increasing by natural revegetation and through plantings and seeding. Fourteen species of seabird currently breed on Phillip Island. Five species—Providence petrel (Pterodroma solandri), Kermadec petrel (P. neglecta), white-naped petrel (P. cervicalis), flesh-footed shearwater (Puffinus carneipes) and red-tailed tropicbird (Phaethon rubricauda)—all have ecologically significant populations. In this paper, we review the current status of the seabird populations breeding on Phillip Island, and suggest how vegetation restoration is likely to affect each species. We update previously published notes and present unpublished material collected by us over more than 3 decades. We document when each species was first discovered, reveal the location of nesting sites, describe breeding phenology and nesting habitat, report on any banding activities and returns, and discuss potential threats.