Dispersal of Tengmalm's Owl Aegolius funereus in relation to prey availability and nesting success

Among Tengmalm's Owls ringed in Norway, natal and female breeding dispersal distances were longer if dispersal took place during a microtine prey population low than if dispersal occurred within a microtine peak. Of the recorded cases of female breeding dispersal, 13% could be termed nomadic (dispersal distance > 100 km). Female and overall natal dispersal distances were longer than female breeding dispersal distances. Natal dispersal distances tended to be longer in females than males. Adult females dispersed farther after nest predation than after successful nesting. Extra mortality in adult females due to nest predation may only be small, and will in itself not select for nomadism, as recently suggested.