Justification of Red List Category
Introduced predators, hunting and habitat degradation are all taking their toll on this pigeon which has undergone a moderately rapid population reduction as a result. It is therefore classified as Near Threatened. If apparent recent increases are sustained, it may be eligible for downlisting in the future.
The global population size has not been quantified, but the species is described as not uncommon (Gibbs et al. 2001).
The species is suspected to be have undergone a moderately rapid decline over three generations (20 years), owing to the impacts of introduced predators, collisions with vehicles and infrastructure, and illegal hunting. However, there has apparently been some recover as the population was considered to be increasing in 2012 (Robertson et al. 2013).
Hemiphaga novaeseelandiae is a forest pigeon endemic to New Zealand, breeding on the North, South and Stewart Islands, Little and Great Barrier Islands, Hen and Chicken Islands, Mayor Island and Kapiti Island (del Hoyo et al. 1997, Gibbs et al. 2001). It underwent rapid declines in Northland - a 1993 survey indicated a 50% decline within 14 years (Pierce et al. 1993), and studies indicate that declines also occurred elsewhere (Mander et al. 1998). The reason(s) for these mortalities has not been established by necropsy but appear to be associated with intestinal disintegration (T. Beauchamp in litt. 2013). There has apparently since been some recovery, as the population was considered to be increasing in 2012 (Robertson et al. 2013). The subspecies spadicea, of Norfolk Island, went extinct in the early 20th century (Schodde et al. 1983).
It breeds in native forest, in the non-breeding season birds also utilise exotic plantations and suburban areas. The species is dependent on fruiting trees and it is considered that only a relatively small number of native species are of great importance (Gibbs et al. 2001). Breeding takes a notably long time, with incubation lasting about 30 days and the young fledging after 6-7 weeks (Gibbs et al. 2001).
Introduced predators are the primary cause of decline nationwide, in particular, brush-tailed possum Trichosurus vulpecula, black rat Rattus rattus, stoat Mustela erminea and cats (Mander et al. 1998). T. vulpecula and R. rattus also compete for fruit, reducing the number of breeding attempts, and possibly causing the starvation of adults (Mander et al. 1998). Loss of forest habitat through burning and clearance for farmland, removal of firewood and browsing by herbivores is also a threat (Aikman et al. 2001) but was more significant in the early 20th century. Birds are illegally hunted for food, particularly in Northland, with perhaps hundreds being shot each year (Heather and Robertson 1997, Pullman and Pullman 1997, Powlesland 2013).
The cause(s) of recent large-scale mortalities has not been established by necropsy, but it appears to be associated with intestinal disintegration. There were two droughts in Northland 2010-11 and 2012-13 and a very wet summer in 2011-12, and some taraire (an important fruiting tree) are showing poor recovery after the last drought. In addition there has been continuing spread of guava moth in northern New Zealand and the potential for myrtle rust to arrive (T. Beauchamp in litt. 2013). Other mortality factors include collisions with fast moving vehicles, overhead power and telephone wires and windows, and electrocution when perched on some power poles (Powlesland 2013).
Conservation and research actions underway
In some small areas, intensive predator control has seen numbers undergo unprecedented increases.
51 cm. Large, plump green and white pigeon. Head, throat, upper breast and upperparts metallic green with purple sheen; clearly demarcated white lower breast, underparts and legs; red bill and feet. Similar spp. Hemiphaga chathamensis has a matt blackish-grey head, throat, breast and neck sides, also has dark green rather than white undertail coverts and occurs only on the Chatham Islands. Hint Listen for distinctive noisy wingbeats overhead. Voice Call is typically a single 'kuu', sometimes drawn out into almost a wail, plus some growling at the nest.
Text account compilers
Benstead, P., Khwaja, N., Mahood, S., McClellan, R., Taylor, J., Martin, R & Symes, A.
BirdLife International (2019) Species factsheet: Hemiphaga novaeseelandiae. Downloaded from http://www.birdlife.org on 20/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/08/2019.