The Booted Eagle (Hieraaetus pennatus) was one of the target species in the SEO/BirdLife-brokered national woodland raptor survey 2009-2010 (Palomino and Valls, 2011). The estimated Extremadura population came out as 2210 territories (range 2150-2270). This represents 12% of the Spanish total (18,500 territories), ranking fourth after three bigger regions: Castilla y León (3820), Andalucía (3790) and Castilla-La Mancha (3020). Extremadura's mean density is 5.3 territories per 100 km2, the highest in the whole country and way above the national mean (3.7). Behind Extremadura come Andalucía, Aragón and Castilla y León (densities of from 4.1 to 4.3).
Badajoz, with an estimated 1200 territories, boasts Spain's biggest provincial population, followed by Cáceres with 1010 territories. The highest provincial density is recorded by Sevilla (5.8), followed by Badajoz (5.5), Huelva (5.11) and Cáceres (5.08), all in the southwest quadrant of mainland Spain.
The Booted Eagle's range takes in the whole of Extremadura; it seems to be commonest in the northern half of Cáceres and scarcest in the centre-west of Badajoz. In all it was recorded in 57% of the grids with lookout points (65% in Cáceres and 52% in Badajoz). The Booted Eagle is a very versatile raptor. In Spain it prefers inland areas with cool, sunny springs, moderate relief and not too much farmland.
The car transects threw up an average of 4.4 birds every 100 km; it was observed in 77% of the sampled grids (83% in Cáceres and 71% in Badajoz). The mean birds-per-kilometre figure for Spain as a whole was 2.3, led by Salamanca (5.7), Valladolid (5.6), Segovia (4.8), Cáceres (4.5), Granada (4.5) y Badajoz (4.2).
The Booted Eagle's trend in Spain is a very sharp increase according to the breeding birds monitoring project SACRE, with a 43% rise from 1998 to 2010. In the central zone of Spain, including Extremadura, the increase is even higher: 53%. Gibraltar Strait counts of migrating birds have also multiplied fourfold since the 1990s, with almost 30,000 Booted Eagles being recorded nowadays (Fundación Migres).
As regards the figures thrown up by this survey, not much can be said because there is insufficient previous information to go on. Nonetheless some discrepancies are evident in the above paragraphs. The population estimates clearly bring out the importance of the southwest quadrant of mainland Spain (Extremadura and Western Andalucía), while the observation probability map (bound up with abundance) shows the highest probabilities in Cáceres and the south of the northern meseta. The same goes for the car transects, with highest bird-per-kilometre figures in the northern meseta. In both cases Salamanca comes out winning while Badajoz and Sevilla come out losing.
The fieldwork was coordinated and carried out by SEO volunteers and staff of the Environment Board of the Regional Council of Extremadura.
- Palomino, D., y Valls, J. 2011. Las rapaces forestales en España. Población reproductora en 2009-2010 y método de censo. SEO/BirdLife. Madrid. [PDF]
- Fundación Migres: http://www.fundacionmigres.org/Noticia_aumento_poblaciones_rapaces.html