Conservation team study rare Rwandan warblers

23-11-2004

In Rwanda, a team of BP Conservation Award winners studying two globally threatened warbler species have been busy in the northwestern part of the country. After preliminary surveys in the Albertine Rift region, the team found that the Endangered Grauer's Scrub-warbler Bradypterus graueri has a viable population but is unevenly distributed in the Rugezi swamp, which has a high amount of human interference. Sound recordings gave a very preliminary suggestion that there were about 370 singing males in the population.

The other species, the Vulnerable Papyrus Yellow Warbler Chloropeta gracilirostris, was represented by only a few individuals in an apparently rehabilitated papyrus patch, and habitat disturbance is viewed as the most likely culprit for their low numbers. Habitat preference for both birds is still not documented, since in some disturbed areas the birds are thriving and in others they are not. Factors such as the type and extent of the disturbance may be the cause of the variation, and the team is continuing to study these mysteries.

These two species of birds are extremely shy and elusive, and apparently even the most experienced researchers find them very difficult to study. However, after some short rains passed through the study area, the team noticed a measurable increase in the number of birds they were able to record, and they are excited to return to the field once the water table has increased.

One last positive observation was that in Volcano National Park, the Grauer's Scrub-warbler was greatly benefitting from the protection of other wildlife, such as the Mountain Gorilla, yet their habitat density was still much lower there than in Rugezi swamp. All of these phenonmena will be analysed once the team has returned from the field after the rains.