Species

BirdLife Species Champion	Become a BirdLife Preventing Extinctions Programme Supporter
For information about BirdLife Species Champions and Species Guardians visit the BirdLife Preventing Extinctions Programme.

Justification
This secretive species qualifies as Endangered because it has a very small, fragmented range and population which are declining owing to hunting and habitat loss and degradation (partly driven by cyclones). The lack of recent records suggests that all subpopulations may now be so small that the species may warrant uplisting to Critically Endangered in the near future.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Identification
31 cm. Chunky, dark pigeon with heavy, hooked bill. Lower mandible has two "teeth" that overlap the upper. Mostly greenish-black with chestnut upperparts. Bill red at base, then yellow. Red eye-ring. Similar spp. Metallic Pigeon Columba vitiensis and White-throated Imperial-pigeon Ducula pacifica slimmer and longer tailed with no chestnut on upperparts. Voice Uniform territorial coo, higher-pitched in female. Irregular, frequent repetitions (Beichle 1991). Hints Prefers to stand on thick branches in dark interior of tree-crowns, often 15-20 m high, but up to 40 m (Beichle 1982).

Distribution and population
Didunculus strigirostris is endemic to Samoa, where it is known as Manumea; its total population was estimated at 4,800-7,200 birds in the mid-1980s (Beichle 1987), but in the 1990s the population showed a drastic decline owing to the effects of cyclones such that, in 2000, fewer than 2,500 mature individuals were believed to survive. In 1999 and 2000, surveys on Savai`i showed that it had become rare with pairs scattered in suitable habitat. An eleven month survey in 2005-2006 reported the species from only ten locations, and the population was estimated to number only a few hundred, although the remote and largely intact uplands of Savai'i remain largely unsurveyed (Ministry of Natural Resources and the Environment, Samoa 2006). Small numbers were recorded in a few locations on Upolu in 2009, but lack of recent sightings among local hunters further suggests that declines are continuing (R. Stirnemann and M. O'Brien in litt. 2011). There is concern that these small, increasingly fragmented subpopulations may not be viable (H. Freifeld in litt. 1999). A single individual on Nu`utele in 2010 may have been an immigrant from Upolu (M. O'Brien in litt. 2011). Surveys of the Savai'i uplands are planned to take place in 2012 (M. O'Brien in litt. 2011).

Population justification
The population estimate of 1,000-2,499 individuals is derived from U. Beichle (in litt. 2000). This equates to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals. The lack of recent records suggests that the total population may now be far lower than this, possibly fewer than 250 mature individuals, but further work is needed to confirm this.

Trend justification
No new data are available on population trends, but the species is suspected to still be suffering from the partially synergistic effects of forest degradation by cyclones and invasive tree species, as well as accidental mortality from hunting and direct loss of habitat through agricultural expansion. The rate of decline is assumed to have slowed, from very rapid over the last ten years to moderately rapid over the next ten years, since it is not thought that the island has experienced any additional cyclones.

Ecology
It occurs in primary forest from sea-level to 1,600 m, also occurring in forest edge, along forest roads and sometimes visiting clearings where native trees remain (Beichle 1987, Blockstein 1987, U. Beichle in litt. 2000). It is specialised to feed on the seeds of Dysoxylum spp. (using its unusual bill to saw through the tough, fibrous pericarp), also feeding on other fleshy fruit (Beichle 1987). Clutch-size is probably two (Beichle 1987).

Threats
It is threatened by deforestation for agriculture, and also the severe effects of cyclones, e.g. in 1990 and 1991, when canopy cover was reduced from 100% to 27% (Elmqvist et al. 1994) and up to 95% of large trees may have been lost in some areas (D. Scott in litt. 2012) and more recently when cyclones passed close to the islands (J. Atherton in litt. 2007). Forest quality is further reduced by the subsequent invasion of highly aggressive non-native trees (H. Freifeld in litt. 1999). Hunting is also a further threat, e.g. in 1985, 400 birds were being shot every year (Beichle and Maelzer 1985). Although hunting is now illegal, birds are still shot in the seasonal harvest of unprotected pigeon species (Blockstein 1987). Predation of eggs and nestlings by Pacific rats Rattus exulans may represent a threat.


Conservation actions underway
It is fully protected by law and hunting is banned, though this has not been enforced. It occurs in some proposed and a few existing protected areas, but these have suffered cyclone damage and the O Le Pupu Pu`e National Park on `Upolu is threatened by logging and cattle-farming (Beichle and Maelzer 1985). It has been chosen as a flagship species to promote conservation awareness, and was selected as the mascot of the South Pacific Games held in 2007 in Samoa, in order to promote bird and forest conservation. A species recovery plan was published by the Samoan Ministry of Natural Resources and Environment and funds are now being sought to implement the plan. Surveys of the Savai'i uplands are planned for 2012.

Conservation actions proposed
Implement the species recovery plan prepared for this species. Extend the hunting ban to cover all native columbids to avoid "mistaken" shooting (U. Beichle in litt. 2000). Conduct further surveys to determine its distribution and population numbers and gather further information on its life-history and habitat requirements (Freifeld 1999, SPREP 1999, U. Beichle in litt. 2000). Investigate threats (Freifeld 1999, SPREP 1999). Identify important sites, set up a network of long-term monitoring stations, and establish conservation areas/nature reserves, e.g. on the four small islands off the east coast of `Upolu including Nu`utele (Aleipata) (Freifeld 1999, SPREP 1999, U. Beichle in litt. 2000). Increase local involvement in its study and conservation (Freifeld 1999, SPREP 1999). Consider establishing a captive population, and, in due course, consider translocations to islands such as the rat-free Nu`utele if these are found to be suitable.

References
Beichle, U. 1982. Untersuchungen zur Biologie und Systematik der Zahntaube Didunculus strigirostris (Jardine 1845). dissertation. Doctoral, Kiel:Christian-Albrechts Universitat.

Beichle, U.; Maelzer, M. 1985. A conservation programme for Western Samoa. In: Diamond, A.W.; Lovejoy, T.E. (ed.), Conservation of tropical forest birds, pp. 297-299. International Council for Bird Preservation, Cambridge, U.K.

Beichle, U. 1987. Lebensraum, Bestand und Nahrungsaufnahme der Zahntaube, Didunculus strigirostris. Journal für Ornithologie 128: 75-89.

Blockstein, D. E. 1987. Preliminary report on the ecology and status of the Tooth-billed Pigeon or "Manumea" (Didunculus strigirostris) in Western Samoa.

Beichle, U. 1991. Status and acoustical demarcation of pigeons of Western Samoa. Notornis 38: 81-86.

Elmqvist, T.; Rainey, W. E.; Pierson, E. D.; Cox, P. A. 1994. Effects of tropical cyclones Ofa and Val on the structure of a Samoan lowland rain forest. Biotropica 26: 384-391.

SPREP. 1999. Proceedings of the Polynesian Avifauna Conservation Workshop held in Rarotonga, 26-30 April 1999.

Freifeld, H. 1999. Samoa bird studies - preliminary ideas for O Le Siosiomaga Society, Inc..

Ministry of Natural Resources & Environment, Government of Samoa. 2006. Recovery Plan for the Ma’oma’o or Mao (Gymnomyza samoensis).

Beichle, U. and Bauchmann, S. 2003. Die Landvoegel der Samoa-Inseln. TenDenZen 1-2: 1-156.

Beichle, U. 2006. Saving Samoa’s Critically Endangered Maomao and Manumea: Final Report.

Further web sources of information
View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Mahood, S., O'Brien, A., Shutes, S., Stattersfield, A., Symes, A.

Contributors
Atherton, J., Beichle, U., Freifeld, H., Hobcroft, D., O'Brien, M., Scott, D., Stirnemann, R.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2013) Species factsheet: Didunculus strigirostris. Downloaded from http://www.birdlife.org on 23/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.