“The swallows have the air for their province. On tireless wings, with open mouths, they sieve the air, taking millions of tiny gnats, mosquitoes, and flies, that would make life altogether unbearable for us were we compelled to live and breathe among them in their unchecked development” – Gene Stratton-Porter, Homing with the Birds.
One study conducted by the United States Geological Survey focused on environmental contaminants which are byproducts of industry and agriculture. Tree Swallows usually nest near water and eat emergent aquatic insects. Contaminants found in the water are absorbed by the insects and when eaten by a swallow, the contaminants remain in the swallow and have harmful effects. Scientists determine the extent and type of contaminants found in the water by examining the eggs and other tissues. They also study the survival rates of the young, and they measure the percentage of banded adults that return to a contaminated nest site each year versus a clean nest site.
Cornell scientist David Winkler regularly studies a set of over 400 nest boxes, 60% of them occupied, near experimental ponds. Winkler has been studying the birds for over 20 years and has written dozens of papers. He is currently trying to develop a swallow network of scientists across the globe for the Golondrinas de las Americas project. He hopes the comparative studies will help us better understand the life history of the swallows and ways in which birds respond to climate change. On his website, Winkler says that he enjoys working with Tree Swallows because “they have a ton of gumption and a lot of character. They are tough birds, and they don’t hold a grudge. They don’t abandon their nests. You can just pick them like fruit. You can create your own populations.”