Northern Harrier (Circus cyaneus) Science Article 1
Hen Harrier chicks were wing-tagged in four regions in Scotland and in North Wales between 1990 and 1995, and resighted or recovered dead as fully grown birds during the non-breeding season (August to April) throughout Britain and Ireland, and on the Continent, until April 1997. Results were analysed in terms of the percentages of birds that carried out long-distance movements (over 25 km) and the extent of the long-distance movements. The percentages of first-year birds undertaking longdistance movements were related to natal area, sex and season. A higher percentage of first-year males in the East Highlands undertook long-distance movements than females. For first-year birds that made long-distance movements, there were significant effects of season and natal area, and interactions. Thus, longer movements occurred in winter and spring, and males from the North Highlands made the longest movements. Records on the Continent referred mainly to first-year males. For all age classes, the percentage of birds undertaking long-distance movements was related only to sex; males making a higher percentage than females. For those that made long-distance movements, there were effects of season, age and sex, and interactions. In autumn, the most distant sightings and recoveries were of first-year males, and the shortest were of adult males. The lengths and directions of movements taken by males and females from different natal areas were interpreted as due to the locations of upland natal areas relative to lowland wintering areas, and food availability in lowland and upland habitats affecting the sexes differently.
Brian Etheridge and Ron W. Summers, Ringing & Migration (2006) 23, 6-14