Human Impact on Critically Endangered Waterbird Beneficial

A white-shouldered ibis in Cambodia. Human impact on this critically endangered bird can be beneficial rather than destructive, and could even save it from extinction. (Credit: Hugh Wright)

ScienceDaily (July 26, 2009) — Human impact on one of the world's most threatened bird species can be beneficial rather than destructive - and could even save it from extinction - according to counterintuitive new findings by the University of East Anglia (UEA).

Published in the peer-reviewed journal Animal Conservation, the study by UEA conservation experts explores the exact reasons behind the decline of the critically endangered white-shouldered ibis.

The new study was carried out in Western Siem Pang Important Bird Area (IBA), northern Cambodia, where 160-200 of the birds survive – around half of the global population.

Working in partnership with BirdLife International, the researchers found that the ibis prefer to forage in open and accessible sites with low vegetation and bare soil. This is believed to be because it makes it easier to find prey, aids take-off and landing, and improves detection of approaching danger.

Traditional small-scale farming by local communities is therefore crucial to the ibis' survival because grazing livestock and burning of the forest understorey opens up these habitats making them suitable for the birds.

"Our findings show that this critically endangered species is largely dependent on the local farmers for their survival," said lead author Hugh Wright, of UEA's School of Environmental Sciences. "This is a fascinating outcome as we tend to assume that human activity always has a negative impact on the natural world."

Not all human influence is positive for the endangered ibis, however. Western Siem Pang - currently an unprotected site – is under imminent threat from large-scale development which would destroy the birds' habitats entirely, along with the local farming communities.

"The Forestry Administration in Cambodia is supportive of a proposal to make the area a protected forest and we believe that this – along with the continuation of local farming methods practiced for generation after generation – will be crucial in saving this once common species from extinction," added Hugh.

With fewer than 500 individuals remaining, mainly in Cambodia, the white-shouldered ibis has undergone the most rapid decline of all South-East Asia's large waterbirds and is now the most threatened. Once common in Myanmar, Thailand, Laos, Cambodia, Vietnam and Indonesia, the precise causes behind the bird's continuing decline have until now been poorly understood, which has hindered conservation efforts.

This research was funded by the Royal Society for the Protection of Birds (RSPB) and the Natural Environment Research Council (NERC).