Raptors Worldwide. Budapest: WWGBP & MME.
Home range size, Habitat utilisation, Hunting and Time budgets of Lesser Spotted Eagles Aquila pomarina with regard to Disturbance and Landscape Fragmentation
Bernd-U. Meyburg, Wolfgang Scheller and Ugis Bergmanis
The extent of the home range, habitat utilization and time budget of the Lesser Spotted Eagle (LSE) were examined with particular regard to disturbance and landscape fragmentation in North-eastern Germany at the western edge of its range and, for comparison purposes, in Latvia. The results, based on conventional VHF radio-telemetry backed up by visual observation, produced valuable data on home range coverage (which was significantly greater than recorded in earlier studies) and the characteristics and utilization of preferred hunting grounds.
A total of 9 birds in Germany, and 6 birds in Latvia, were studied. The home ranges exploited by successful breeding males in Germany were significantly larger than those in Latvia, averaging 2,711.2 ha compared with a 1,142.7 ha. The maximum/minimum ranges covered in Germany were 3,393.8 ha/2,218.5 ha compared with 1,552 ha/672 ha in Latvia. There was no marked difference between the average daily home range of 347.3 ha and 483.8 ha in Germany (mean 471.9 ha) and between 244.3 ha and 489.3 ha (mean 361.2 ha) in Latvia. There was little difference in the maximum daily home range size in Germany 1,287.5 ha and in Latvia 1,156.0 ha.
All eagles used open countryside considerably more than forested areas for hunting. All of the Latvian and most of the German males showed a clear preference for grassland as hunting habitat. In Latvia grassland, where the availability in the home range was correspondingly greater, was used morefrequently and for longer periods (39%) of total hunting time (24.5% Germany). The proportion was reversed in hunting over arable land because of the smaller percentage of grassland in Germany where cereal crops or set-asides were preferred for hunting in the vegetation period; hunting over rape and maize crops began generally after the harvest. There was a difference in the proportion of individual hunting methods. Perch hunting dominated among the Latvian birds, the German birds mainly hunted on the wing.
Wide-open and unbroken countryside must be preserved in breeding area concentrations, with potential disturbance factors confined to marginal zones. All forms of infrastructural development (particularly road construction) must be strictly controlled here.
The following disturbance factors must be excluded from an area up to 3 km radius from the nest, the main hunting zone: tourism, all substantial urban development and installations involving substantial habitat change (e.g. wind turbines).