Fish Eagle research in Cambodia

Grey-headed Fishing Eagle, Photo © Ruth Tingay

The ECA is supporting a study of the grey-headed fishing eagle (Ichthyophaga ichthyaetus) in Cambodia by Natural Research, in cooperation with the University of Reading and the Wildlife Conservation Society. The eagle is very poorly known and its population is in apparent decline throughout its Indo-Malayan range; its global conservation status is "Near Threatened".

The work the ECA is funding is focused on learning more about the status and ecological requirements of this eagle. Thus far the research has documented a previously-unknown high density breeding population in a flooded swamp forest (Prek Toal) at the northwest end of the huge Tonle Sap Lake in northern Cambodia (the largest fresh water lake in SE Asia). Indeed, this concentration may be the largest in SE Asia.

The research has found at least 50 breeding pairs of eagles within a core study area of the lake, and studies of diet have revealed that the grey-headed fishing eagle on the lake is not a specialist piscivore, as its name suggests, but feeds on at least three species of homalopsine water snakes.

Currently, the stability of this population is threatened by activities (likely unsustainable) at local and international scales, particularly the massive exploitation of water snakes (an estimated 6.9 million snakes are removed from the lake annually), and the construction of upstream hydro-power dams in China (affecting water and silt levels in the Tonle Sap Lake). A cascade of eight dams is planned for the Chinese Mekong, with two (the Manwan and Dachaoshan) already in operation.

The work has already produced peer-reviewed published results, and a second publication recently was submitted for review:

Tingay, R.E., Nicoll, M.A.C. & Sun, V. (2006). Status and distribution of the grey-headed fishing eagle (Ichthyophaga ichthyaetus) in the Prek Toal Core Area of Tonle Sap Lake, Cambodia. Journal of Raptor Research 40 (4): 277-283.

Tingay, R.E., Whitfield, D.P., Nicoll, M.A.C., McLeod, D.R.A. & Sun, V. (submitted). Using an avian top predator to monitor environmental change in a threatened landscape: the grey-headed fishing eagle at Tonle Sap Lake, Cambodia.

This project places great emphasis on local capacity building at the project site, to help train and support local biologists to enable them to lead the project in the future. Cambodian ornithologist, Sun Visal, has been trained in a variety of raptor research field skills, including transect surveys, data collection and monitoring techniques. In 2007 Visal won a fully-funded four month internship at Hawk Mountain Sanctuary, USA, to help develop his research skills. He returned to Cambodia where he led the 2007 grey-headed fishing eagle fieldwork. In April 2008, using funding from this project he attended the Asian Raptor Research and Conservation Network conference in Vietnam, where he presented a poster and met other raptor biologists from his region, exchanged ideas and worked to develop future partnerships and collaborations.

Future Plans

The project will undertake further surveys in other areas of swamp forest around the Tonle Sap Lake, with a particular emphasis on the two other Core Areas (protected reserves), to determine the distribution and abundance of grey-headed fishing eagles at the lake. WCS Cambodia and the Royal Government of Cambodia have invited Natural Research and its partners to submit a fishing eagle monitoring protocol for use at other key sites on the Tonle Sap Lake, as part of their on-going biodiversity strategy. Using the monitoring scheme we have established at Prek Toal, we intend to hold a workshop for government wildlife officers from the two other Core Areas, to train them in the relevant techniques so they can undertake surveys and monitoring in these other areas.

In the long-term the project will undertake further research at Prek Toal to better understand the breeding biology and ecology of the grey-headed fishing eagle. Of particular interest is the relationship between the breeding adult eagles and the water snakes, as well as understanding the dispersal movements of juvenile fishing eagles, as they are rarely seen in our study area.

Apart from the ECA, the project has benefited from the generous financial support of Natural Research, the National Birds of Prey Trust, Hawk Mountain Sanctuary, the International Osprey Foundation, University of Reading, and the Wildlife Conservation Society.

You can learn more about this project by reading the Natural Research project page. You can learn about other projects done by Natural Research by visiting their web page www.natural-research.org and surfing.