Some aspects of the spring migration of the Willow Warbler Phylloscopus trochilus, on the isle of Capri


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Some aspects of the migration of the Willow Warbler Phy/loscopus trochilus were studied on the isle of Capri in the spring of 1987. 309 individuals were captured between ApriI 13th and May 24th. 200 m of nets were used in groups of 20-30 m each within an area covering approx. l hectare and made up of Mediterranean bush. The trend of the capture, which was concentrated in the second half of the month of ApriI, did not appear to be determined simply by the different transit of males and females in the species but also by groups of different individuals. In the nominaI ssp. 2 different groups of individuals were distinguished, one characterized by colour note 2, the other by colour notes 3 and 4, according to the amount of yellow streaks on the breast and belly. The study examines the rnigratory transit and differences in fatty deposits between males and females in the three groups. The ssp. acredula, which is distinguished by wing length, appears different from the nominaI ssp. also in the transit periodo