Birds are the most popular downloads on the site, though they also offer other animals such as bears, alligators, wolves, whales, and other awesome animal noises. The site hopes to raise awareness about the state of the earth and the animals on it.
There is but a catch: to get the free ringtones, you have to sign up for an e-mail newsletter from the group. Of course, since this is actually a useful e-mail for activists and animal enthusiasts alike, there's no reason to complain about that!
The free endangered animal ringtones can be found at the Center For Biological Diversity Web site. They're perfect choice for the socially and environmentally conscious... and while they seem an unlikely pairing, they really do make perfect sense.