Endangered Wetar Ground-dove “rediscovered” on Wetar Island, Indonesia
Scientists working for the UK-based conservation charity Columbidae Conservation have rediscovered the endangered Wetar Ground-dove (Gallicolumba hoedtii), one of the world’s least known birds, on the island after which it is named. There have been no official records of the species on Wetar Island for 100 years. These initial observations on Wetar are therefore very good news for the species’ future conservation as apart from Wetar, an island located in eastern Indonesia, the species only occurs on one other island, the neighbouring island of Timor (Indonesia / Timor-Leste). The project continues; after fulfilling its initial aim to determine whether the Wetar Ground-dove was still present on Wetar, data are now being collected on its distribution, habitat requirements and identify any threats it may be facing.

The scientists report that not only has the species been rediscovered but it is likely to be locally abundant. At one location, the team observed a congregation of 30-40 birds feeding on fallen fig (Ficus) fruits – this represents by far the largest ever recorded gathering. The team also reported that another endangered species of pigeon, the Timor Imperial Pigeon (Ducula cineracea) is also locally abundant. At the time of writing, 39 new bird species have been recorded for the island. Colin Trainor, who is leading the research team, described the island as “amazing – it has an incredible abundance of pigeons and parrots, and bird life in general. For the Wetar Ground-dove it seems very likely that Wetar is the species stronghold”.

Wetar is a large island (3600 km2) with incredibly steep hilly-mountainous terrain that maintains extensive forest cover (c. 80%) ranging from tropical evergreen forest to tropical dry forest, as well as Eucalyptus savannas and hill forests. Trainor said of Wetar Island “for its size it must be the single most pristine in South-East Asia”. Dr. Jonathan Walker, director of Columbidae Conservation, and project coordinator said of the team’s observations to date “its fantastic news - even without yet completing the fieldwork and analysing the data it's very clear that Wetar is a very high conservation priority in the region”.

However, Trainor has also identified strong pressure to develop the island. Of immediate conservation concern is the ongoing construction of an asphalt road, already 12 km long, that will follow valley floors currently covered in pristine forest and open up the interior of the island. For now the team will continue with their surveys of the island and collect further data on the Wetar Ground-dove and its other wildlife, and determine the conservation priorities on the island. Back in the UK, Columbidae Conservation is already planning future work to safeguard this biologically valuable island both for the Wetar Ground-dove and the islands’ other wildlife (Columbidae Conservation 21.10.2008).

For more information on this project 'click here' .

Emerald Dove negatively affected by invasivion of Yellow Crazy Ants
Australian scientists have found that invasion by the Yellow Crazy Ant (Anoplolepis gracilipes), a pantropical invader rapidly expanding its range, has ecological effects that extend upward to birds. They compared counts, behaviors, and nesting success of three endemic forest birds in ant-invaded and uninvaded rainforest on Christmas Island (Indian Ocean): Emerald Dove (Chalcophaps indica natalis); Island Thrush (Turdus poliocephalus erythropleurus); and Christmas Island White-eye (Zosterops natalis). The Island Thrush, which frequents the forest floor, altered its foraging and reproductive behaviors in ant-invaded forest (nest-site location changed and nest success and juvenile counts were lower); Christmas Island White-eye, a generalist feeder in the understory and canopy, were more abundant in ant-invaded forest, where mutualism between the ant and honeydew secreting scale insects increased the abundance of scale-insect prey. The Emerald Dove which forages exclusively on the forest floor, were 9–14 times lower in ant-invaded forest. The authors suggest that direct interference by ants and the altered resource availability and habitat structure that extend to these endemic forest birds may affect key ecosystem processes, including seed dispersal.

Davis, N.E., O’Dowd, D.J. (odowd “at” sci.monash.edu.au), Green, P.T. and Mac Nally, R. (2008) Effects of an alien ant invasion on abundance, behavior, and reproductive success of endemic island birds. Conservation Biology 22(5): 1165–1176.

Tropical Cyclone Heta plus hunting responsible for decline of the Pacific pigeon Ducula pacifica
On 6 January 2004, Tropical Cyclone Heta devastated much of the South Pacific island nation of Niue. The forest suffered extensive damage with many trees uprooted and others stripped of branches and foliage. Scientists from the New Zealand Department of Conservation surveyed these species during September 2004 and compared the results with those from a similar survey 10 years previously in September 1994. Along three study transects they found variable results between transects and years for the Purple-crowned Fruit-dove (Kulukulu; Ptilinopus porphyraceus) but detected significantly fewer Pacific Pigeon (Lupe) along all three transects in 2004 than previously. The authors tentatively suggest that the decline in the Lupe population was caused mainly by unsustainable human hunting during 1994–2004, rather than mortality caused by the cyclone. This is a result of hunting being part of the culture of indigenous peoples and advantage being taken birds in weakened states from food shortages. Many other Lupe were preyed upon by cats and dogs.

Powlesland, R.G. (rpowlesland "at" doc.govt.nz), Butler, D.J. and Westbrooke, I.M. (2008) Was tropical cyclone Heta or hunting by people responsible for decline of the Lupe (Ducula pacifica) (Aves: Columbidae) population on Niue during 1994–2004? Pacific Science 62(4): 461-472.

Mortality in Band-tailed Pigeons from the protozoan parasite Trichomonas gallinae
Band-tailed Pigeons (Patagioenas fasciata) wintering at Hastings Reservation in central coastal California during winter 2006–2007 died in large numbers between January and March 2007. Laboratory analysis of carcasses indicated that Trichomonas gallinae was responsible for the die-off, which is estimated to have killed ~43,000 pigeons. This estimate of mortality is nearly three times the largest trichomoniasis mortality event previously recorded for Band-tailed Pigeons and is at least twice the number harvested annually in the United States. Local mortality of pigeons in Monterey County, California may have been several times this estimate based on the presence of considerable similar habitat in the nearby Ventana Wilderness.

Stromberg, M.R., Koenig, W.D., Walters E.L. (ewalters “at” ley.edu) and Schweisinger, J. (2008) Estimate of Trichomonas gallinae-induced mortality in Band-tailed Pigeons, Upper Carmel Valley, California, winter 2006–2007. The Wilson Journal of Ornithology 120(3): 603–606.

Faecal DNA analysis enables non-invasive study of sympatric pigeons
Bolle’s Laurel Pigeon Columba bollii and the White-tailed Pigeon C. junoniae are two endemic pigeons from the relict laurel forest of the Canary Islands (Eastern Atlantic Ocean, Spain). Once widespread on the archipelago, habitat destruction, illegal hunting and predation by rats have led to them being listed as Near Threatened (C. bollii) and Endangered (C. junoniae). These two columbids probably evolved in different habitats (laurel and thermophilous forest, respectively), but the almost total destruction of these latter forests could force the White-tailed Pigeon to occupy laurel forest areas. The rarity and elusive behaviour of the species makes it difficult to observe and handle individuals. The collection of faecal samples collected from the field allows a non-invasive method to enable DNA analysis of diet and distribution. However, reliable identification of faeces is required in order to identify the target species and these two species faeces are morphologically indistinguishable because they have similar body sizes and probably share similar food resources. Scientists from the Canary Islands, Spain, have successfully pioneered the technique of faecal DNA analysis not just for these species, but for birds. The application of the present methodology could provide the basis for further studies of these species, for example, through mapping species ranges, identification of key habitats, studies of trophic ecology and analyses of genetic variability. More generally, the protocol presented in the study could be used in a broader context for other congeneric vertebrate species.

Marrero, P. (pmarrero “at” ipna.csic.es), Cabrera, V.M., Padilla, D.P. and Nogales, M. (2008) Molecular identification of two threatened pigeon species (Columbidae) using faecal samples. Ibis 150: 820–823 (Bolle’s Laurel Pigeon Columba bollii; White-tailed Pigeon Columba junoniae).