‘Seriously Weird’, the Bird with a False Penis

The red-billed buffalo weaver possesses one of the most bizarre consequences of the force of sexual competition in evolution – particularly the competition between males to be the one whose sperm fertilises a female’s eggs. The male of the southern African species boasts a finger-like appendage between his legs. “This is seriously weird”, thought ornithologist Tim Birkhead when he first heard about the red-billed buffalo weaver. After receiving a specimen in the post from Africa, stalking the birds in Namibia and raising some in an aviary, Tim thinks he’s cracked why the males have evolved a false penis. Could it be Nature’s own tickling stick?