[Porterville]

From:http://www.netfundu.com/magazine/oct02/birds.htm One of the most interesting aspects of Hoatzin ecology is that young birds have a pair of claws on the bend of each wing. When confronted with danger, the young birds drop out of the tree into the water. They wait there until the danger has passed and climb back up to their nest with the help of their clawed wings. Adult birds have another means of defense; they can produce on offensive odor that drives enemies away. Hence, it is commonly called "the stink bird".

[Porterville]