"Effects of disturbance, habitat loss and fragmentation on prairie birds and their ecosystems"

点击翻译按钮获取中文摘要

Grassland birds have declined more than birds from any other ecosystem in North America. I study why grassland songbird populations are declining, and what we can do about it. I integrate theory with field studies to develop a better understanding of effects of disturbance (which includes grazing by native animals, grazing by cattle, and fire) on grassland songbirds. I also study effects of habitat loss and fragmentation on birds. My research program has a number of subthemes. The first explores effects of livestock grazing. To do this, I use a grazing experiment in Grasslands National Park in southern Saskatchewan. We introduced cattle at a range of stocking rates to understand how grazing intensity influences birds and their ecosystems. After 5 years of grazing, we will remove cattle from these pastures, to understand how quickly prairies recover following different grazing intensities. The second subtheme is to apply behavioral ecology to better understand why most songbirds have higher densities in larger prairies. This is particularly important to conservation of tall-grass prairies in southern Manitoba, where most remaining prairies are very small, and thus are avoided by grassland birds. One reason might be that songbirds prefer to settle in prairies near other songbirds. To test if this is true, we will conduct an experiment in which we will play recordings of bird songs to see whether this results in the recolonization of unoccupied prairie fragments. The third subtheme is to better understand effects of habitat amount and fragmentation on grassland birds. South-west Manitoba has many threatened and endangered species. We are interested in whether declines in grassland birds were caused directly by habitat loss, such as conversion of prairies to cropland, or were caused indirectly, for example due to edge effects. We are testing this by surveying birds in south-west Manitoba, in a range of landscapes in which grassland amount and fragmentation are not correlated. This will help us determine what habitat management strategies would be most likely to help us conserve birds.