Mynah bird, a very invasive species © Gideon Climo
Studying wildlife diseases is also vital to conservation of biodiversity. Visiting scientists Joanna Chitty and Andre Raine, from the University of East Anglia in UK, are currently making a study of the blood-parasites of Seychelles birds. It is hoped this work will contribute to our understanding of the patterns of infection affecting Seychelles birds and the history of how these parasites came to be in the islands.
The focus of their study is avian malaria. Avian malarias are found in birds the world over and cannot affect humans. In some countries malarias have had a devastating impact on rare birds. For example on the Hawaiian Islands the extinction of fifteen bird species and the critical endangerment of seven more is thought to be due to avian malaria.
Infectious disease is considered a major issue in conservation. Illnesses can be devastating to small, isolated populations of plants or animals that are already threatened. Even where living things are not obviously vulnerable and there is plenty of good habitat, species can succumb to disease. Many species of rainforest frogs have been lost globally due to disease alone. Here in Seychelles we have seen diseases wipe out the Takamaka and Sandragon trees.
Avian malarias may not have an immediate catastrophic effect on Seychelles birds as it is believed they have a long history in the area, having coexisted with the birds for millennia. Nonetheless, such parasites may have more subtle effects, for example on the survival of young or which areas species can inhabit.
The study hopes to discover which malarias are harboured by rare and threatened bird species and how these relate to those in common birds. It should make it possible to judge whether introduced species are bringing new parasites into the islands. It will reveal whether Seychelles bird-parasites are related to those in Africa, the rest of world or whether unique parasites have evolved here. It will tell us whether parasites are common to all species and islands, or whether different strains occur in different places.
It is hoped that the information will contribute to assessing the risk of new diseases occurring in the birds here. In addition, understanding avian malaria in the unique island bird fauna of Seychelles will add to the scientific understanding of the relationships between birds and disease and how these have evolved.
As a final note about wildlife and its diseases, many of the features of birds that we find so engaging and interesting are owed to the long, historic battle with parasites. The bright feather colours and exaggerated plumage of male birds are believed by evolutionary biologists to act as displays of health, or absence of disease, to the female. Others believe that diseases and parasites can drive species into new habitats, where they adapt and ultimately evolve into new species. So while ferocious predators may grab the animal headlines, never underestimate the importance of small things.
Nature Seychelles, 1st August 2006.