Evidence for the existence of a leading line effect in Honey buzzard migration through Malta

Abstract

The effect of leading lines in raptor migration is well known, and is though to be one reason for the large concentrations of raptors which occurs at the narrows at both seasons. Recent analyses of the extensive observations carried out at Falsterbo has led to the elaboration of a model which relates the leading line effect to weather phenomena, especially wind. Honey buzzard Pernis apivorus migration through Malta in autumn is thought to be subject to similar leading line effects, albeit on a much smaller scale. The effect is thought to increase in strength as the afternoon progresses. Increasing strength of the southerly (contrary) component of surface wind strength is also thought to induce more birds to follow the coast rather than commence migration over the sea immediately. Some evidence for the existence of a leading line effect in Malta is presented below.