Researchers found that birds were more evolutionarily similar on smaller, more isolated islands than on larger, less remote places. The team had expected to find that forested areas had more numerous and more varied species of birds compared to farmland areas. But they were surprised to find that the opposite was true: Areas with farms and human settlements had more species of birds and greater diversity than forested areas.
Scientists still don’t fully understand the consequences that pollution and climate change can have on the world around us. Now, a new peer-reviewed study published in the Proceedings of the Royal Society examining bird populations living on islands shows we may know even less than previously thought.
“Usually, one predicts that there should be fewer species of birds living in agricultural areas where trees have been removed and the land manipulated than in natural habitats like forests,” said Luke O. Frishkoff, assistant professor of biology at The University of Texas at Arlington. “But strangely, on the islands we studied off the coast of China, we found opposite patterns with the communities of birds under examination — there were more bird species in agriculture than in forested areas.”
Along with researchers from East China Normal University in Shanghai, the University of Birmingham in the United Kingdom, and the University of Pittsburgh Medical Center, Frishkoff examined birds living in the Zhoushan Archipelago, the largest chain of islands in China. They chose islands as a place to study birds because while islands make up only 5% of the Earth’s land mass, they support 20% of the world’s species of animals.
The team surveyed birds during the breeding season along 34 islands — some forested, some used for farmland, some more isolated than others. They particularly looked for small and remote islands with farmland habitats. Bird populations were tracked in four separate surveys over two years.
“Human activities have extensively modified habitats on three-quarters of all the Earth’s surface worldwide, and islands are no different,” Frishkoff said.
The researchers found that birds were more evolutionarily similar on smaller, more isolated islands than on larger, less remote places. The team had expected to find that forested areas had more numerous and more varied species of birds compared to farmland areas. But they were surprised to find that the opposite was true: Areas with farms and human settlements had more species of birds and greater diversity than forested areas.
“All this is suggesting that there are some fundamental principles of ecology that we don’t yet understand, and that there is perhaps something special about islands that affects species that can tolerate human environments differently than species that require natural ecosystems for sur-vival,” Frishkoff said. “We need additional research to better understand why bird evolution, and the evolution of species in general, is different on islands so that we can better protect and sustain biodiversity in other human-dominated ecosystems.”
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