Sadly, despite the outlawing of DDT and the rehabilitation of some species affected by it, birds as a whole are moving ever closer to the silent spring of Carson's worst nightmares. That is up from one percent in 1958, when comprehensive surveys began. The IUCN lists nearly 100 species as critically endangered, meaning that at current rates of decline, they face a 50 percent chance of extinction within the next five years. These are not isolated animals wrestling with special problems. It is easy to become overwhelmed by numbers, and lose touch with the tragedy they represent.
Birds live on the edge.
Smaller birds must feed constantly to maintain body heat and the energy necessary for flight. In order to feed all year long, many take the incredible risk of flying thousands of miles to feeding grounds in another hemisphere. Breeding, with all its attendant courtship rituals, takes even more energy. Like most other animals on the margins of survival, many bird species produce as many offspring as possible in the hopes that enough individuals will survive to continue the lineage. Probably one-third don't even hatch.