First coordinated White-shouldered Ibis count dramatically increases known population

White-shouldered Ibis Pseudibis davisoni, Western  Siem Pang, Cambodia. Photo credit: Jonathan C. Eames

For the first time a nationwide coordinated count of Critically Endangered White-shouldered Ibis Pseudibis davisoni has been carried out in Cambodia. 310 individuals were found, making it the largest count of White-shouldered Ibis ever, and providing evidence that the world population of the species is larger than previously estimated.

 
In July, the University of East Anglia (UEA), in cooperation with BirdLife International in Indochina, Wildlife Conservation Society (WCS), and World Wildlife Fund for Nature (WWF), with support from the Forestry Administration, Ministry of Agriculture, Forestry and Fisheries (FA and MAFF), and the General Department of Administration for Nature Conservation and Protection, Ministry of Environment (GDANCP and MoE), surveyed four sites in Cambodia, to better understand the species.

A total of 310 individuals was counted at four sites, comprising:  Western Siem Pang Important Bird Area, Stung Treng province; Lomphat Wildlife Sanctuary, Ratanakiri and Mondulkiri provinces; Kulen Promtep Wildlife Sanctuary, Preah Vihear province; and the "central section" of the Mekong River, a 56 km stretch between Kratie and Stung Treng provinces.

The 2009 IUCN Red List estimates that the world population of the White-shouldered Ibis is no more than 249 mature individuals, and possibly as low as 50.

UEA PhD student Hugh Wright, who has been leading White-shouldered Ibis research for 18 months, said, "This is the first time we have achieved a reliable minimum figure for the population size of White-shouldered Ibis in Cambodia. The recent count means the population is almost certainly larger than the IUCN estimate of 50-249 mature individuals, however there is a good chance that the population is even larger than 310 because we expect to find more roost sites and count more birds."

 This is the first time we have achieved a reliable minimum figure for the population size of White-shouldered Ibis in Cambodia.

"Nevertheless, it is unlikely that the population has increased or is recovering, instead we are just starting to make more effort to count them and searching in more places. Their scarcity after a steep decline and preference for remote parts of the country has made it difficult to count their numbers until now," continued Mr. Wright.

The exact reasons for White-shouldered Ibis’ population decline in the last few decades remains something of a mystery, although hunting and habitat destruction are likely to have played a part. UEA, and partners, are currently researching the species’ ecology to find the best methods for conservation action. This coming breeding season will see new activities to understand why nests fail and how they can be protected.

Funding for this work was provided by the Critical Ecosystem Partnership Fund [1], the British Ornithologists’ Union, the Global Environment Facility, United Nations Development Program, and the Angkor Centre for the Conservation of Biodiversity (ACCB).

The next coordinated roost count will be happening in early September. With more roosts being found every month, the population figure will become increasingly accurate, to help inform conservationists of the true status of the species.