Data Zone
Justification of Red List category
This species has a large population size and range, and although there is thought to be a decline in mature individuals, this is not thought to approach 30% in three generations. For these reasons the species is assessed as Least Concern.
Population justification
Applying known density estimates and broad estimations of the area of occupancy, the population of G. s. smithii was estimated at 108,000 [81,000-136,000] (Davies et al. 2021) while G. s. blaauwi was estimated at 8,500 [800-9,400] (Swann et al. 2021), giving a total population estimate of 116,500 mature individuals for the species.
Trend justification
In plots across Kakadu, which covers approximately half the range of G. s. smithii, the average density fell from c.3.0 birds/km2 in 2001–2004 to 0.63 birds/km2 in 2007–2009 (Woinarski et al. 2012). Losses are also likely to have occurred on the fringes of Darwin as development has intensified. However, the mainland range has been stable and given the isolation, size and stability of the Tiwi Islands population, overall declines of G. s. smithii are considered unlikely to have met or approached 30% in the last three generations (Davies et al. 2021).
Data on the trend of G. s. blaauwi are principally anecdotal, with flock sizes at known locations appearing to get smaller. Around Kimbolton for example, where the population appears to be stable but localised within a broader survey area, maximum flock size each year from 2017–2020 was 33, 10, 16 and 18, respectively (M. Bruton/AWC unpublished, in Swann et al. 2021). However, a decline approaching 30% in three generations is unlikely and the subpopulation comprises approximately only 7% of the total number of mature individuals and is therefore unlikely to substantially affect the global trend.
Overall, the trend of the global population is therefore inferred to be declining, suspected here at a broadly continuing rate of 5-19% over three generations.
The species is endemic to Australia. G. s. smithii occur in the Top End of the Northern Territory from near Katherine in the south, west to Litchfield National Park, north to Berry Springs, near Darwin, and as far north as Coburg Peninsula and Croker Island. The distribution in Arnhem Land is poorly known, though there are several records from the north-east coast. There is also a population on the Tiwi Islands (both Melville and Bathurst Islands) with smaller scattered and potentially isolated populations elsewhere in the Top End (Woinarski 2004, Woinarski et al. 2007). G. s. blaauwi occurs within 100 km of the coast in north-western Australia between Kalumburu and the Mitchell Plateau and Kimbolton, including Prince Regent National Park, Glenelg River and Bachsten Creek (Higgins & Davies 1996). Specimens have been obtained historically from as far east as the Durack River (House 1902).
G. s. smithii primarily inhabits open forest and woodland dominated by Eucalyptus tetrodonta and E. miniata that has a structurally diverse understorey, usually in areas with a fire regime that promotes a mosaic of fire ages, including wet season burns, which promote grass diversity and year-round seed availability (Fraser et al. 2003). The ground cover is mostly tall grasses, though the pigeons are usually seen feeding in recently burnt areas, by roads and in short grass (Johnstone 1981, in Garnett et al. 2011). It appears to rely on perennial grass species which set seed relatively early (Fraser 2001). Breeding takes place in the dry season, between March and October, and the species usually lays two eggs in rudimentary nests made on the ground, most often at the base of a clump of grass. It feeds on seeds taken from bare ground. It may benefit from the recent spread of introduced cane toads Bufo marinus throughout large parts of its range, as the toads are likely to cause severe reductions in monitor lizards Varanus spp. and snakes, which are likely to be predators of the species and its eggs and young (J. Woinarski in litt. 2007). Fire regimes are changing across much of its range, with more extensive high-intensity fires, reducing the fine-scale mosaic favoured by this species. This unfavourable change is likely to accelerate with ongoing spread of invasive pasture grasses (Setterfield et al. 2010, 2013). Fire may also magnify impacts due to predation by feral cats, with recent research in the partridge pigeon’s range showing that cats are attracted to burnt areas and have high predation impact in them (McGregor et al. 2015, 2016; Leahy et al. 2015). G. s. blaauwi, like the eastern subspecies, appears to prefer a mix of recently burnt areas for feeding and perennial grasses for shelter (Johnstone 1981, Fraser 2001, Fraser et al. 2003).
The principal threats to G. s. smithii are thought to be changes in fire regime and predation by cats Felis catus (Fraser 2001, Fraser et al. 2003). Fire management remained problematic in Kakadu National Park up to 2016 (Russell-Smith et al. 2017); since then a strategic fire program has been instituted and has reduced the extent and severity of fire in the park (Director of National Parks unpublished). However, there is no evidence to suggest any recent change in fire intensity or frequency, feral animal densities or exotic plant abundance on the Tiwi Islands (Davies et al. 2019). The spread of exotic grasses, particularly gamba grass Andropogon gayanus and clearance for plantation forestry and intensive agriculture, particularly cattle grazing, is likely to be affecting birds on the fringes of their range. However, most of their range is currently unaffected and G. s. smithii still occur within Tiwi Islands forestry plantations. G. s. blaauwi are affected by similar threats. Feral cattle Bos taurus are overgrazing the flatter country where the species lives (G. Swann unpublished) and feral donkeys Equus asinus have also been common and are a possible threat (DEWHA 2008). The frequency of late dry season fire was very high in the region until recently (Legge et al. 2011). Partridge Pigeons are particularly vulnerable to predation by cats Felis catus, which are prevalent in the region (McGregor et al. 2015), as they nest and forage on the ground, live in relatively open habitats and, averaging 190 g (Garnett et al. 2015), fall within the 60–300 g weight range that cats prefer (Woinarski et al. 2017). However, the prevalence of small mammals in the region may reduce the risk of cat predation (Davies et al. 2019). There are currently efforts to diminish the damage done by late dry season fires and control cattle and donkeys with active research on cat control (Corey and Radford 2017).
Conservation Actions Underway
Many parts of the range are managed for conservation. Listed as threatened under appropriate legislation. Fire management is reducing late dry season fire frequency. Feral herbivore control is reducing numbers of feral cattle and donkeys (Davies et al. 2021, Swann et al. 2021).
Conservation Actions Proposed
Investigate effects of the spread of exotic pasture grasses and grazing on behaviour and abundance (J. Woinarski in litt. 2007). Determine breeding success and the factors that affect it (particularly the significance of feral cat predation) (J. Woinarski in litt. 2007). Develop robust monitoring techniques, and monitor abundance in landscapes under different management regimes, or in selected accessible parts of range. Continue to undertake annual fire planning and management, managing land with a fine-scale mosaic of burning across the range. Control populations of introduced herbivores and cats as appropriate.
Text account compilers
Berryman, A., Vine, J.
Contributors
Woinarski, J.C.Z.
Recommended citation
BirdLife International (2024) Species factsheet: Partridge Pigeon Geophaps smithii. Downloaded from
https://datazone.birdlife.org/species/factsheet/partridge-pigeon-geophaps-smithii on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.