Monday, 21 November 2011


Short-Toed Eagle (Circaetus gallicus). Eva Palacios.

The Short-Toed Eagle (Circaetus gallicus) was another 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 980 territories (range 940-1020). This represents 9.4% of the Spanish total (10,380 territories), ranking fifth behind the bigger regions of Castilla-La Mancha (1800), Castilla y León (1760), Andalucía (1620) and Aragón (1340). Extremadura's mean density is 2.4 territories per 100 km2, above the national average of 2.1 and behind only Aragón (2'8) and the Valencia Region (2.7).

Cáceres, with an estimated 570 territories, boasts Spain's biggest provincial population, albeit ranking fourth in density (2.87 territories per 100 km2) behind Castellón, Teruel and Guadalajara. Badajoz, for its part, accounts for 410 territories, 1.88 every 100 km2 (the 30th highest density in Spain).

The Short-Toed Eagle ranges widely over the whole of Extremadura. It is especially abundant in the eastern half of Cáceres and the northeast corner of Badajoz, the two areas with the highest sighting probability in the whole of Spain. Although it is less common in the province of Badajoz, especially in its western half, some parts of the province still throw up the highest one-off densities in the whole of Spain (2.5 territories in only 10 km2). In all it was detected in 41% of the surveyed 10k grids. In Spain the Short-Toed Eagle favours low-altitude, high insolation areas with extensive Holm Oak woods, warm but with a certain humidity and little farmland.

Predictive map of the Short-Toed Eagle's (Circaetus gallicus) range in Spain, taken from Palomino and Valls (2011). This clearly shows that the eastern half of Cáceres offers the highest likelihood of a Short-Toed Eagle sighting.

On the Extremadura car transects 2.5 birds were seen every 100 km; it tuned up in 65% of the sampled grids. The mean birds-per-kilometre figure for Spain as a whole was 1.6, led by Castellón (4.4), La Rioja (2.8), Ciudad Real (2.8), Badajoz (2.7), Segovia (2.7) and Cáceres (2.4).

The Short-Toed Eagle's trend in Spain is stable according to the breeding birds monitoring project SACRE, although migration figures across the Strait of Gibraltar increased at an annual rate of 6.6% over the 1998-2009 period. Given that Spain's population is the biggest in Europe, it is logical to conclude that it is on the increase; this is born out by comparing the birds-per-kilometre figure with previous studies.

Not much can be added to the SEO/BirdLife results. The apparent discrepancy between the different surveying methods (for example, Cáceres is the province with the highest sighting rate from lookout points but only the sixth in car transects) is only to be expected in samples where the zones visited might be different and there are also several factors that might muddy the subsequent analysis (low territoriality, territory overlaps and shared hunting grounds).

The fieldwork was coordinated and carried out by SEO volunteers and staff of the Environment Board of the Regional Council of Extremadura.

- Palomino, D., and Valls, J. 2011. Las rapaces forestales en España. Población reproductora en 2009-2010 y método de censo. SEO/BirdLife. Madrid [PDF]