EN
Palau Ground-dove Alopecoenas canifrons



Justification

Justification of Red List Category
This species has a very small population and is considered to be declining due to invasive species and habitat loss. For these reasons it is listed as Endangered.

Population justification
The species occurs throughout the Palau archipelago but it is rare on most islands. Surveys in 1977-79 estimated a total population of approximately 500 individuals (Engbring, unpublished data, as cited in Engbring and Pratt 1985) Subsequent surveys have recorded very few individuals (Engbring 1992, VanderWerf 2007, Horii 2018), so they cannot provide reliable population estimates, but indicate that the total population is now likely to be smaller than 500 individuals. The population is therefore placed in the band 250-999 mature individuals.

Trend justification
Whilst the species was previously estimated to have a population of 500 individuals (Engbring, unpublished data, as cited in Engbring and Pratt 1985), there have been very few records during recent surveys (Engbring 1992, VanderWerf 2007, Horii 2018, D. Horii in litt. 2018). Rats and cats are known to be present on some of its range islands (G. McKinlay in litt. 2018) and may prey on adults, chicks and eggs. An analysis of forest cover found that between 2000 and 2012, forest had been lost from the species's range at a rate equivalent to 4.3% across three generations (Tracewski et al. 2016). The species can therefore be inferred to be declining.

Distribution and population

Alopecoenas canifrons is endemic to Palau where it is found in dense forest on all the major islands from Babeldaob (very rare) to Angaur, and on many of the small limestone islands south of Koror known as the Rock Islands (Engbring 1988). The species is difficult to locate because of its secretive habits, sparse vocalisations (H. D. Pratt in litt. 1999) and inaccessible habitat. Surveys in 1977-79 estimated a total population of approximately 500 individuals (Engbring, unpublished data, as cited in Engbring and Pratt 1985). In 1991, the U.S. Fish and Wildlife Service conducted surveys of the birds of Palau (Engbring 1992). Using a variable circular plot method, they calculated a population density of 0.4 birds/km2 and estimated a population of 164 individuals. However, these findings were based on only nine recorded birds, so the estimate cannot be considered reliable. Another survey of the birds of Palau took place in 2005 (VanderWerf 2007) and followed a similar method to the 1991 survey. An index of relative abundance was calculated for each species and was expressed as the average number of birds per survey station. This survey recorded only four individuals and was again unable to provide a meaningful population estimate, but a relative abundance of 0.006±0.003 birds per survey station was reported (cf. 0.015 birds per station in 1991; Engbring 1992). The lower numbers of forest birds recorded in 2005 in comparison with 1991 may have been a result of a drought associated with El Niño weather patterns in 1997-98 (VanderWerf 2007). VanderWerf also reported that the species was easily observed in a coastal area of Ulong Island not included in the 1991 or 2005 surveys (VanderWerf 2007). Since October 2017, monthly surveys have been carried out across the Rock Islands. During these surveys from October 2017 to June 2018, there have been no records of the species (Horii 2018, D. Horii in litt. 2018). It has been reported that it is now seldom seen at Ulong Island, where there has been clearance of vegetation and increased human disturbance (G. McKinlay in litt. 2018). Rats and cats are present on some of the species's range islands and are both likely to pose a threat (G. McKinlay in litt. 2018). An analysis of remote-sensed forest cover data found that between 2000 and 2012, forest was lost from the species's range at a rate equivalent to 4.3% across three generations (Tracewski et al. 2016).

Ecology

It prefers limestone islands, inhabiting forest on rocky terrain. It is terrestrial, foraging for fallen fruits and seeds in places where deep leaf-litter has accumulated, such as gullies and hollows.

Threats

The introduction of alien species (e.g. rats, Brown Tree Snake Boiga irregularis) is a serious potential threat (Sherley 2001). Cats are present in some rock islands, Babeldaob, Carp island, and presumably Peleliu (G. McKinlay in litt. 2018). Rats are abundant in some parts of the species's range (G. McKinlay in litt. 2018). The Palau Conservation Society reported observing a ground dove being killed by a rat in 2005 (A. Gupta in litt. 2011). Forest has been cleared for the construction of roads, houses and farms (VanderWerf 2007, Ketebengang and Gupta 2011). An analysis of remote-sensed forest cover data found that between 2000 and 2012, forest was lost from the species's range at a rate equivalent to 4.3% across three generations (Tracewski et al. 2016). Vegetation has been cleared and human disturbance has increased at Ulong Island, where the species was formerly reliably observed (G. McKinlay in litt. 2018). 

Conservation actions

Conservation Actions Underway
The species was included in the 1991 and 2005 National Bird Survey conducted by the Palau Conservation Society and the U.S. Fish and Wildlife Service. Surveys are currently underway on the Rock Islands (Horii 2018, D. Horii in litt. 2018).

Conservation Actions Proposed
Monitor the population across the species's range to assess the species's population size and trends. Investigate the impact of cats and rats on the species. Take measures to prevent the accidental introduction of the Brown Tree Snake (B. irregularis) to islands important for the species. Control invasive mammals. Protect the species's forest habitat across its range, including through the creation of more protected areas (Ketebengang and Gupta 2011).

Acknowledgements

Text account compilers
Derhé, M., Benstead, P., O'Brien, A., Shutes, S., Stattersfield, A., Wheatley, H., Mahood, S.

Contributors
Horii, D., Pratt, H., Davis, R., McKinlay, G., Gupta, A.


Recommended citation
BirdLife International (2019) Species factsheet: Alopecoenas canifrons. Downloaded from http://www.birdlife.org on 19/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2019.