Migration and wintering areas of adult Montagu's Harriers (Circus pygargus) breeding in Spain

Abstract

Between 2006 and 2008, 14 Montagu's Harriers (Circus pygargus) were tagged with satellite transmitters at their breeding grounds in NE Spain, recording a total of 18 autumn and 10 spring journeys. In both autumn and spring migrations, harriers migrated between Europe and West Africa along a relatively narrow corridor between the coast of Morocco and Western Sahara and the western border of Algeria. Birds tended to follow a slightly more westerly track during spring migration compared to autumn migration. Harriers started autumn migration in late August-early September, arriving at their wintering grounds in early-mid-September, after travelling between 8 and 25 days, and covering a mean of 187 km a day. Spring migration started in mid-March, with birds arriving at the breeding grounds in mid-April after covering a mean of 114 km a day. On average, spring migration lasted longer, with birds covering longer distances than during autumn migration, and distances travelled in a day tended to be shorter. Significant differences in the routes followed by harriers were observed among seasons and individuals, with the same individuals following different routes in different years. Wintering areas were located in northern Senegal and the southern border of Mauritania with Mali, with some birds breeding in the same colony in Europe separated more than 1,200 km during the wintering season. Birds showed a relatively high fidelity to their wintering areas. Several birds moved from one area to another during the wintering period, which resulted in larger wintering areas, whereas others remained in the same area during the whole wintering season.