Richard Hill, Birds Australia
Environment Australia, May 2002
Habitat Critical to Survival
Until the late 1700s Norfolk Island was covered in dense forests and the Green Parrot was probably widely distributed across the island. Between the late 1700s and 1800s, felling of forest tree species led to considerable deforestation. Clearing for agriculture and plantation production further reduced native vegetation cover. By the late 1800s the Green Parrot was confined to the area now included in NINP. Since then, the structure and composition of the remaining native vegetation has changed dramatically primarily through weed invasion and grazing (Anon 1984).
The most extensive area of native habitat remaining on Norfolk Island is within NINP, which encompasses 465 ha (12%) of the island. Gilmour and Helman (1989) quantified the native vegetation assemblages of the Park as 30% 'native forest' (palm, hardwood, and Norfolk Island Pine forest), 37% 'weed-infested native forest' and 33% 'exotic forest' (see also Schodde et al. 1983).
Green Parrots forage in all habitats within the park except for a small area of eucalypt plantation (J. Hicks, pers.comm.) and in some areas outside of the park. The principle diet of adult Green Parrots appears to be a variety of native seeds, fruits, flowers, and leaves. This includes Norfolk Island Pine (Araucaria heterophylla), Ironwood (Nestegis apetala), Norfolk Island Palm (Rhopalostylis baureri var. baueri), Bloodwood (Baloghia inophylla), Cordyline (Cordyline obtecta) and Whiteoak (Lagunaria patersonia spp. patersonia) (Forshaw 1981, Hicks and Preece 1991). Seeds, fruit and bark of some exotic species are also consumed, namely Red Guava, African Olive and Lantana (Lantana camara) (Hicks and Preece 1991).
African Olive and Red Guava seeds may now form a significant part of the diet of newly-fledged juveniles (Davidson 1997, Motte and Hall 1988), with Bloodwood seeds, Norfolk Island Pine seed and green and fallen Red Guava fruit also important (Davidson 1997).
No quantitative studies have been conducted on the foraging preferences and nutritional value of native and exotic foods in the diet of wild Green Parrots. Captive Green Parrots readily accept native Norfolk Island herbs (Chaff-flower Achyranthes aspera seed, Pig Face Carpobrotus glaucescens leaves and fruit, Mile-a-minute Wollastonia biflora flowers and fruit). Hicks and Preece (1991) note that although the NI Green Parrot feeds in forest trees, other closely related Cyanoramphus spp. occur and forage in grassland environments eg. the Kermadec Parakeet (C.n.cyanurus) on Macauley Island and the Red-fronted Parakeet (C.n.novaezelandiae) on Tiritiri Island (NZ).
Parrots typically forage from early to mid-morning, flying between favoured feeding areas in pairs or small parties (Davidson 1997, Forshaw 1981). From mid-morning to late afternoon parrots move to sunny (but unexposed) positions near the tops of trees, where they preen quietly and are inconspicuous (Forshaw 1981). Adults forage mostly in the tops of trees and occasionally on the ground (Forshaw 1981, Hicks and Preece 1991), while juveniles, for 3-5 weeks after fledging, feed extensively on the ground eating the fallen seeds of African Olive and Red Guava (Davidson 1997). Davidson (1997) recorded a total of 244 perch locations from 3 radio-tracked juveniles, of which 58 (24%) were on the ground, 101 (41%) were in African Olive and Red Guava and 85 (35%) were in 12 native tree species. It is unclear whether frequent foraging in exotic vegetation reflects a preference for olive and guava by juveniles or the widespread abundance of these species in NINP (Davidson 1997).
Wild birds often feed in the Norfolk Island Botanic Garden and visit the aviaries where captive parrots are held. The subspecies is not shy (Forshaw 1981) and has been recorded foraging in gardens (Davidson 1997). From 1991-1998, 31 possible sightings of Green Parrots outside NINP were made. The majority of sightings were in December and January, the peak breeding season for wild Green Parrots.
The Green Parrot's breeding range is now believed to be restricted to the National Park. Natural nest sites are known only in hollows of native tree species, typically within 2 m of the ground (Hicks and Preece 1991). Of 43 wild nests monitored between 1983 and 1988, all were in native species. Twenty-eight of 43 nests were in Ironwood, 11 were in Cordyline, 2 were in Norfolk Island Pine and 2 were in Whiteoak. There appears to be a significant relationship between vegetation type and location of nesting site. Native forest is the most used nesting habitat, followed by 'weed-infested native forest' then 'dense Red Guava' forest. 'Dense African Olive forest' supported the lowest number of nests. Adults usually return to the same nest site each season (Hicks and Preece 1991). No nests have been located in 'plantation forests' probably because the trees are immature. Potential extensions of habitat exist outside the National Park if nesting hollows were provided and maintained, and predator control measures were introduced.
Critical habitat is defined as all habitats used by this taxa. These include all known sites for nesting, and food resources, water shelter etc, as defined by the EPBC (1999). This includes native and exotic forest and areas inside and outside of the NINP. Habitat with the potential to support Green Parrots also fit the criteria for critical habitat, and the revegetated areas of Phillip Island may well be critical habitat, as well as potential habitat on Norfolk Island currently not used by Green Parrots. The critical habitat of the Green Parrot is mapped in Figure 1 and is defined in this plan as all potential Green Parrot habitat within its 'current normal range'.