The enduring question of sex-biased dispersal: Paul J. Greenwood's (1980) seminal contribution

► Greenwood (1980, 28, 1140-1162) is the most cited article in Animal Behaviour, with close to 2000 citations. ► It invoked the type of mating system to explain natal dispersal of birds and mammals. ► In birds, males show resource defence and females disperse. ► In mammals, males show mate defence and they disperse. ► New hypotheses invoke local kin competition and emphasize phylogenetic comparisons.