| Description |
Increased human domination of the planet has caused the declines and extinctions of countless species. Each species has not only intrinsic value, but ecological functions of organisms are also essential for the integrity of ecosystems that allow people to benefit from essential free ecosystem services, such as carcass disposal, pest control, pollination and seed dispersal. In order to retain global biodiversity and ecosystem services, we must study the factors behind species' declines, understand their consequences, improve capacity of human-dominated landscapes to maintain biodiversity, and persuade local human communities to preserve their natural heritage. With birds as my focal group, I take various approaches to addressing these issues, including an analysis of the world's bird species, modeling bird extinctions in the 21st century, field research on effects of habitat degradation on tropical forest bird communities, a radio telemetry study of forest birds that persist in deforested landscapes, and a review of birdwatching tourism. My research sheds light on the ecological consequences of species' declines, the long-term impacts of tropical forest degradation, the role of mobility for persistence of birds in deforested tropical landscapes, the conservation significance of integrating human-dominated and native habitats, and the importance of local human communities for biodiversity preservation. Analyzing a database of all the world's bird species, I found that certain functional groups, such as frugivores, herbivores, piscivores and scavengers, are more extinction-prone than average, and some areas, such as oceanic islands and forested landscapes, have significantly more species that are at risk. These patterns are likely to deteriorate in the 21st century, signaling the potential loss of crucial ecosystem services such as pest control, pollination, and seed dispersal. In Uganda, I found that beyond a certain intensity, one-time forestry practices can have long-term negative impacts on forest birds through changes in vegetation structure, whereas low intensity forestry can be compatible with the preservation of local biodiversity. The largest simultaneous study of forest understory insectivorous birds, their diets and prey base in the premontane forest fragments of southern Costa Rica showed that these area-sensitive species disappear from small forest fragments not due to lack of food, but because their limited mobility prevents movements between small habitat patches, making them vulnerable to stochastic, local extinctions. On the other hand, three forest bird species that were able to persist in agricultural countryside dominated by coffee plantations were able to do so either by being pre-adapted to disturbed habitats (Catharus aurantiirostris) or by being highly mobile and making efficient use of 11% of the landscape still covered by trees (Tangara icterocephala and Turdus assimilis). Results from radio telemetry also underlined the importance of remnant trees, riparian strips, and small forest patches for native forest species. An analysis of birdwatching tourism revealed that, just as human-dominated landscapes are often excluded from conservation initiatives, most local people in less-developed areas are also excluded from the income generated by birdwatching that is overwhelmingly conducted by wealthy citizens of developed countries. If the combination of large scale habitat clearance, exclusion of human-dominated landscapes from conservation policies, and alienation of local communities from ecotourism initiatives continues, consequent disappearance of species is likely to cause collapses in ecosystems and their services that are crucial for humanity. |
