Common Swift

The Common Swift is a dark, medium-sized aerial bird with a compact body, a short forked tail and exceptionally long, swept-back wings that form a crescent in flight. A small pale throat patch is difficult to see at normal viewing distance. Although its outline can recall a swallow or martin, that resemblance reflects a similar airborne lifestyle rather than close relationship. Its very short legs are adapted mainly for gripping vertical surfaces, not walking on the ground. (Wikipedia, general species account)

Common Swifts spend an extraordinary proportion of their lives aloft, catching airborne insects and spiders, drinking, and sometimes sleeping while flying. Non-breeding birds may remain continuously airborne for many months. Around nesting places they form fast, noisy summer groups often called screaming parties. They attach themselves to walls or enter cavities to breed, and otherwise seldom land voluntarily. The species migrates between breeding areas across Europe and Asia and wintering grounds in Africa. (Wikipedia, general species account)