National Multi-species Recovery plan for the Partridge Pigeon [eastern subspecies] Geophaps smithii smithii, Crested Shrike-tit [northern (sub)species] Falcunculus (frontatus) whitei, Masked Owl [north Australian mainland subspecies] Tyto novaehollandiae kimberli; and Masked Owl [Tiwi Islands subspecies] Tyto novaehollandiae melvillensis, 2004 – 2008
A Recovery Plan prepared under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999
Northern Territory Department of Infrastructure Planning and Environment, 2004
Part B: Distribution and habitat
- Habitat critical to the survival of the species
- Mapping of habitat critical to the survival of the species
- Important populations
The four taxa considered here are restricted to open forests and savanna woodlands of northern Australia.
The most circumscribed distribution is that of the Tiwi masked owl, which is known only from the paired Tiwi islands of Bathurst (1693 km2) and Melville (5788 km2) (Fig. 1). Woinarski et al. (2003a) provided some more detailed information on its range on these islands, noting it to be reasonably widespread on both islands, particularly in the higher rainfall areas of north-west Melville Island, where eucalypt forests are tallest and there are many small patches of monsoon rainforest.
Figure 1. (a) [top] Distribution of the Tiwi masked owl Tyto novaehollandiae melvillensis. Dots indicate records from the New Atlas of Australian Birds (Barrett et al. 2003), covering observations over the period 1998-2002.
Figure 1. (b) [bottom]. Distribution on the Tiwi Islands, from survey records of the NT Department of Infrastructure Planning and Environment (Woinarski et al. 2003a).
The distribution of the mainland north Australian masked owl subspecies T. n. kimberli is very imperfectly known, with remarkably few records across its broad range (Fig. 2). Based on compilation of records from 1998-2002, the New Atlas of Australian Birds (Barrett et al. 2003) reported it from only one 1/4o grid cell (from a total of about 130) in northern Western Australia, two (of a total of about 320) in the Top End of the Northern Territory, one on the Barkly Tableland, and five in northern Queensland. The circumscription of this distribution is confused by (i) a number of dubious or at least unconfirmed records away from its main range (Higgins 1999), such as on the south-west of Cape York Peninsula and in semi-arid Northern Territory; and (ii) whether or not the northeast Cape York Peninsula population is recognised as subspecifically distinct. Curiously, the most authoritative recent source (Higgins 1999) does not include the Kimberley within its mapped range. Recognising the shortcomings in survey information, the current range can be considered to include the north and north-west coastal Kimberley, from Cambridge Gulf south-west to Yampi Sound, including Augustus Island (Johnstone and Storr 1998); the Top End of the Northern Territory, including Cobourg Peninsula, extending south to around Katherine (Storr 1977), with a handful of isolated records from further south, including Jasper Gorge (the Victoria River District), McArthur River station, and Avon Downs (Barkly Tablelands) (Storr 1977; Higgins 1999; Barrett et al. 2003); north-eastern Queensland, including a few early records from north-eastern Cape York Peninsula (Archer-Watson Rivers) (the putative subspecies T. n. galei), with a broader distribution centred on Townsville (extending as far north as Mt Molloy and as far south-east as an early twentieth century record at Coomooboolaroo: Barnard 1925) (Higgins 1999; Barrett et al. 2003). There is little information on trends in population or range, but there have been no recent records near the historic inland central Queensland record (Woinarski and Catterall 2004), and the subspecies is thought to have declined in the Wet Tropics (Nielsen 1996).
Figure 2. Distribution of the north Australian mainland subspecies of masked owl Tyto novaehollandiae kimberli. Dots indicate records from the New Atlas of Australian Birds (Barrett et al. 2003), covering observations over the period 1998-2002.
The eastern subspecies of partridge pigeon G. s. smithii is now largely restricted to the north-west Top End of the Northern Territory, in an area bounded from the Yinberrie Hills (about 50 km N of Katherine) in the South Litchfield NP in the west, Kakadu NP in the east and the Tiwi Islands in the north, with smaller scattered populations elsewhere in the Top End (Fig. 3). Its range formerly extended into lower rainfall areas as far south-east as the McArthur River near Borroloola and as far west as the extreme east Kimberley (Keep River drainage) (Storr 1977; Higgins and Davies 1996; Fraser 2000b). Storr (1977) noted that there were “no recent records from the Keep, Victoria, lower Daly, Katherine, King, Roper and McArthur drainages”.
Figure 3. Distribution of the eastern subspecies of partridge pigeon Geophaps smithii smithii. Dots indicate records from the New Atlas of Australian Birds (Barrett et al. 2003), covering observations over the period 1998-2002.
Earlier claims of the distribution extending to Queensland (Laura-Cooktown area) are in error (Higgins and Davies 1996), although persistent in the literature (e.g. Johnstone and Storr 1998).
The distribution of the northern shrike-tit is very imprecisely known, largely because of the sparsity of records. In a review of its status, Robinson and Woinarski (1992) could locate only 26 records (from 22 sites) of this taxon. There have been a trickle of records since (e.g. Robinson et al. 1992; Franklin et al. 1997; Higgins and Peter 2002). The new Atlas of Australian birds (Barrett et al. 2003) reported northern shrike-tits from three 1/4o grid cells in northern Western Australia and five in the Top End of the Northern Territory. Recognising the limitations imposed by these records, the current range is considered to include much of the Top End of the Northern Territory and Kimberley extending from the McArthur River in the far south-east (although with no records from that region since 1914) to near Derby in the west Kimberley (Fig. 4). Most recent records are from south and west of Katherine and near Derby. There are no records from the relatively well-surveyed high rainfall areas around Darwin, the Cobourg Peninsula and Tiwi Islands, suggesting that it is probably absent from the taller forests in this area.
Figure 4. Distribution of the northern (crested) shrike-tit Falcunculus (frontatus) whitei. Dots indicate records from the New Atlas of Australian Birds (Barrett et al. 2003), covering observations over the period 1998-2002.
The limited amount of ecological information available prevents any tight definition of critical habitat for these taxa. The Tiwi masked owl appears to be most abundant in tall eucalypt open forests, in which tree hollows are relatively plentiful (Woinarski et al. 2003a). There are too few records of the northern Australian mainland subspecies of masked owl to characterise habitat, but it too is dependent on tree hollows.
Within its preferred open forests with grassy understorey, the partridge pigeon may require an intricately burnt mosaic (Fraser et al. 2003).
No clear habitat preference has been described for the northern shrike-tit: it has been reported in a wide range of eucalypt open forests and woodlands, and, less commonly, in a woodlands dominated by Terminalia and Melaleuca species (Robinson and Woinarski 1992; Holmes and Noske 1990; Higgins and Peter 2002).
For the Tiwi masked owl, the (probably single panmictic) population on the Tiwi Islands is, by default, an important population.
For the north Australian mainland subspecies of masked owl, no particular (sub-)population is unarguably peerlessly significant. However, the isolated population on north-eastern Cape York Peninsula may be considered important, because it is possibly morphologically distinctive (perhaps to subspecific level).
For the eastern subspecies of partridge pigeons, the Tiwi Island population may be significant because it may be unusually abundant there, and because its isolation on these islands may provide it some refuge from at least some threatening processes operating on the mainland. The population within Kakadu NP may be important because it is a high profile species there, and a focal species for the implementation of fire management.
For the northern shrike-tit, sites near Derby in the west Kimberley and in an area around 100 km west and south of Katherine have produced most records of this bird over the last few decades, suggesting that they may be unusually abundant in these locations.