Tim Birkhead is a zoologist whose research focuses on populations of birds and their reproduction. Tim has made important contributions to the field of behavioural ecology — the study of how animal behaviour evolves under the influence of environmental pressures. He also studies the competitive actions of male birds’ sperm.
He showed that extrapair paternity — where the offspring raised by a pair are the result of the female mating with an outsider male — is common amongst birds. Tim also demonstrated the existence of ‘guarding techniques’, which are carried out by the male bird in a pair. In studies of the zebra finch, he revealed that the sperm of the last male to mate with a female took precedence for fertilising her eggs.