Threatened species & ecological communities

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
Woinarski, J.C.Z.
Northern Territory Department of Infrastructure Planning and Environment, 2004

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Part A: Species information and general requirements

Introduction

This recovery plan considers four bird taxa largely restricted to open forests and woodlands of tropical northern Australia. This multi-species plan recognises some commonalities in threats facing these taxa, and in management responses, but there are clearly also very distinct differences among the taxa.

Packaging these taxa together in one Recovery Plan is one approach to seeking to improve conservation management in northern Australia. It is recognised that other approaches may also have been suitable for the taxa considered here: for example single species recovery plans for the partridge pigeon (including also the subspecies blaauwi from north-western Australia, not considered here), for the crested shrike-tit (including the subspecies frontatus and leucogaster from south-eastern and south-western Australia respectively) and for masked owl (including the subspecies novaehollandiae and castanops from southern and eastern Australia). Such plans may have had more internal homogeneity, but at the expense of a less clear focus on regional conservation issues that affect a range of bird taxa. Another alternative may have been for an even more inclusive multi-species plan for northern Australian threatened birds more generally, but such may have proven too unwieldy.

Descriptions

The northern shrike-tit forms part of the highly distinctive crested shrike-tit superspecies. The shrike-tit is an arboreal, medium sized bird, with striking black and white markings, and black crest, on the head, with the body green above and yellow below. The bill is conspicuously deep, strong and hooked. The northern shrike-tit is notably smaller than the two other shrike-tit subspecies.

The partridge pigeon is a terrestrial, generally dull-coloured dumpy medium-small pigeon (weight ca. 200g), with the most distinctive feature being a patch of brightly-coloured bare skin around the eye. This is red in the eastern subspecies G. smithii smithii and yellow in the western subspecies G. s. blaauwi. Both subspecies also have a prominent white patch on the underwing that is conspicuous when the bird is in flight.

The masked owl is a large (males ca 600 g., females ca. 1 kg.) owl with prominent heart-shaped facial disc, with plumage highly patterned by speckling, and generally darker on the back and paler below. Compared to two other species of Tyto owls in northern Australia, the grass owl T. capensis and barn owl T. alba, its legs are conspicuously well feathered and its claws and feet large and strong. The northern Australian subspecies T. novaehollandiae kimberli and T. n. melvillensis are smaller than other Australian subspecies.

Taxonomy

The taxonomic status of the northern shrike-tit has been unstable since its discovery. The most recent treatment is that of Schodde and Mason (1999) who recognised it as a distinct species Falcunculus whitei Campbell, 1910. Other recent accounts (e.g. Christidis and Boles 1994; Johnstone 2001; Higgins and Peter 2002) have retained the marginally more traditional view that it is a well-marked (and geographically isolated) subspecies of the crested shrike-tit F. frontatus. Its specific or subspecific categorisation is a line-ball call, reflected here in the use of the equivocating Falcunculus (frontatus) whitei.

There are two well-marked subspecies of partridge pigeon Geophaps smithii (Jardine and Selby, 1830), conventionally labelled the western G. s. blaauwi and eastern G. s. smithii subspecies. The taxonomic status of these subspecies and the species as a whole is well-established. Although there has been some uncertainty about the generic relationship of the partridge pigeon (e.g. Christidis and Boles 1994), the current nomenclature is now widely accepted.

The masked owl Tyto novaehollandiae (Stephens, 1826) is a well-defined species, with a highly fragmented distribution including south-western Australia, Tasmania, south-eastern and eastern Australia, north-eastern Queensland, the monsoonal tropics of the north of the Northern Territory and Kimberley, and southern New Guinea (Higgins 1999). Populations on islands off New Guinea (e.g. Tanimbar, Buru and Manus) have sometimes been included within T. novaehollandiae, but are now generally recognised as specifically distinct (Higgins 1999). Within Australia, four or five subspecies are recognised: T. n. novaehollandiae from south-western Australia and south-eastern Australia as far north as south-eastern Queensland; T .n. castanops from Tasmania; T .n. kimberli from mainland northern Australia; and T. n. melvillensis from the Tiwi Islands, Northern Territory: some sources (e.g. Mason 1983; Schodde and Mason 1997) treat populations on Cape York Peninsula as another subspecies T. n. galei, distinct from T. n. kimberli, but this treatment is contested (Higgins 1999). There are few specimens of T. n. melvillensis, but the most substantial recent treatment (Schodde and Mason 1997) maintains its recognition as a validly distinct subspecies.

Conservation Status

As at March 2004,

the northern shrike-tit Falcunculus (frontatus) whitei is listed as:

It was classified as Endangered in the Action Plan for Australian Birds (Garnett and Crowley 2000).

the eastern subspecies of partridge pigeon Geophaps smithii smithii is listed as:

It was classified as Near Threatened in the Action Plan for Australian Birds (Garnett and Crowley 2000). Johnstone and Storr (1998) regarded this subspecies as “Extinct” in Western Australia.

the Tiwi Islands subspecies of masked owl Tyto novaehollandiae melvillensis is listed as:

It was classified as Endangered in the Action Plan for Australian Birds (Garnett and Crowley 2000).

the north Australian mainland subspecies of masked owl Tyto novaehollandiae kimberli is listed as:

It was classified as Near Threatened in the Action Plan for Australian Birds (Garnett and Crowley 2000).

In each case, the NT status is based on evaluations made in 2003, using the IUCN Red List Categories version 3.1. (IUCN 2001). The national status typically follows assessments made prior to 2000.

Affected interests

The primary affected interests for all four taxa are the Australian and State/Territory conservation agencies, and particularly that of the Northern Territory, in which the bulk of the range for all four taxa occurs.

The ranges of all four taxa fall largely on pastoral leasehold lands and Aboriginal freehold lands, with smaller areas included within military training areas (managed by the Department of Defence), and conservation reserves (including Kakadu NP, co-managed by Parks Australia North). The eastern subspecies of partridge pigeon occurs in the peri-urban area around Darwin, where there is increasing land development for horticulture and rural residential estates.

None of the species is commercially exploited.

On Melville Island, the Tiwi Masked Owl occurs in sites in or around a developing major forestry venture that replaces native vegetation with short-rotation exotic plantation species (Woinarski et al. 2003ab). To a degree uncertain because of limited sampling, some or all or the taxa occur on lands devoted primarily to mining.

One such instance is the presence of partridge pigeons on the uranium leases of Ranger and Jabiluka enclosed within Kakadu NP.

Role and interests of indigenous people

As noted in the above section, much of the range of all four taxa occurs on Aboriginal lands. Although masked owls are known and named within many Aboriginal cultures (e.g. Puruntatameri et al. 2001), no special significance has been attributed to them across the published ethnobiological literature. There has been no published information on any indigenous knowledge of, or significance attributed to, the northern shrike-tit.

In contrast, the partridge pigeon is well-known by Aboriginal groups on whose land it occurs: it is a conspicuous, locally abundant, distinctive, ground-dwelling, moderately large, diurnal bird, offering a reasonable food resource. The best documentation of this interest is in Kakadu NP, where partridge pigeons (known as Raagu in Gagudju language; or “red-eye pigeon” colloquially) is regarded as an indicator of seasons and burning regimes. In Kakadu NP, Fraser et al. (2003) used a cross-cultural study to examine the response of partridge pigeons to fire regimes, and suggested that traditional fine-scale landscape burning by Aboriginal people provided the most suitable habitat for this species. On the Tiwi Islands, Northern Territory, Tiwi Aboriginal people know the partridge pigeon as Mapulinka, “the same Tiwi name as the Emerald Dove, (although) these pigeons are recognised as quite distinct. The flesh of these birds can be eaten after roasting. In the past they were hunted with wooden implements and traps, more recent hunting involves shot-guns or using a slingshot, the latter being used mostly by children” (Puruntatameri et al. 2001).

Benefits to other species

The four taxa considered here share similarities mostly in the habitat and geographic range occupied, but contrast conspicuously in their ecology and resource requirements. The main collateral benefit of improved management for these four taxa will be for the biodiversity in tropical eucalypt forests and savanna woodlands generally. This may be particularly so where fire management is improved.

The partridge pigeon may be an exemplar of a large suite of granivorous birds that have declined, and continue to decline, across much of northern Australia (Franklin 1999; Garnett and Crowley 2000; Woinarski and Catterall 2004). It is likely that land management actions implemented to improve habitat suitability (and/or reduce predation by feral cats) for partridge pigeons would also benefit many other co-occurring granivorous birds, particularly including chestnut-backed button-quail Turnix catanota, masked finch Poephila personata, long-tailed finch P. acuticauda, the endangered gouldian finch Erythrura gouldiae and hooded parrot Psephotus dissimilis. Such action would probably also benefit a range of northern Australian terrestrial small and medium-sized mammal species, whose decline has coincided with that of the partridge pigeon and has probably likewise been associated, at least in part, with changed fire regimes (Woinarski et al. 2001, 2004; Pardon et al. 2003).

Management to enhance habitat suitability for masked owls may benefit the many other hollow-dependent species in northern Australia (Taylor et al. 2003), including red-tailed black-cockatoo Calyptorhynchus banksii, sulphur-crested cockatoo Cacatua galerita, dollarbird Eurystomus orientalis, common brushtailed possum Trichosurus vulpecula and black-footed tree-rat Mesembriomys gouldii.

Social and economic impacts

There are no clearcut and tightly defined social and economic impacts associated with this Recovery Plan. Much of the distribution of these four taxa is on Aboriginal land. Research on, and management of, these species may provide some limited contributions to these local economies. Fraser et al. (2003) demonstrated that there may be much scope for Aboriginal involvement in recovery actions for the partridge pigeons, and that traditional Aboriginal fire management may be important for this species.

At least two (partridge pigeon and Tiwi masked owl) of the four taxa have some distributional overlap or convergence with large mining or forestry operations. Conservation management for the species may come at some costs to these ventures, but such costs are generally likely to be low because the disturbances are generally not on lands that provide high quality habitat to these species. A possible exception is for the Tiwi masked owl and partridge pigeon on Melville Island, where forestry development is occurring on lands with high suitability for these taxa.

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