As their name suggests, these swifts nest in caves, on cliffs and in chimneys. Among other interesting features like their nimble aerial acrobatics, they roost by hooking onto vertical surfaces. They are able to achieve this feat due to the unusual configuration of their feet. As opposed to perching or climbing birds, two of the Chimney Swifts’ toes can point backwards or forwards (Pamprodactyl, below), allowing them to hang out in unlikely places.