Wednesday 24 August 2011


Short-Toed Eagle (Circaetus gallicus). Adult feeding its chick with a Horseshoe Whip Snake (Hemorrhois hippocrepis). Photo: Juan Tevar (taken from SEO/BirdLife).

The latest Spanish Bird Monitoring Report (No.36) brought out by SEO/BirdLife deals with woodland raptors (Palomino and Valls, 2011). In the springs of 2009 and 2010 the fieldwork was carried out to ascertain national populations of seven diurnal woodland (or at least tree-nesting) raptors for the first time: Honey Buzzard, Short-Toed Eagle, Goshawk, Sparrow Hawk, Buzzard, Booted Eagle and Hobby. The figures gleaned also helped to update information on Red Kite and Black Kite, both dealt with in recent national surveys, in 2004 and 2005.

The sampling method was twofold: (1) low-speed car transects and (2) lookout points with good views. The national coverage was good, with records for 1059 10-m2 grids, 27,440 km of vehicle transects and 2614 lookout points adding up to about 9000 viewing hours. The coverage in Extremadura was very good, with 4187 km of transects in 113 grids and lookout points in 81 grids. As a region it ranked first in the number of vehicle transects and second in lookout points. The transect results are expressed as birds per kilometre, a widely employed abundance measurement that allows for comparison with previous studies; it is especially useful for raptors that hunt over open-country (buzzard, short-toed eagle, booted eagle and the two kite species). In the lookout points a note was made of all birds seen in each 10-minute period, an objective, abundance-related value that measures the observation frequency. Observers also gave their subjective estimate of the number of territories existing within the viewpoint area. On the basis of these three values (birds per kilometre, frequency and territories) a distribution and abundance map was built up for each species in Spain together with an estimate of the population size (expressed in territories, not necessarily of breeding birds). The latter result is shown in the following table:
The set of these nine raptors make up a total of 108,340 territories in Spain and 10,843 in Extremadura; this means that Extremadura ranks fourth among Spanish regions behind Castilla y León, Andalucía and Castilla-La Mancha, all bigger regions. In terms of density, however (21.5 territories/100 km2 in Spain), the Atlantic regions of northern Spain come first, as might be expected: Basque Country (28.1), Asturias (27.4), Cantabria (26.6) and Galicia (26.2). Extremadura 26.0) comes fifth in terms of density, albeit clocking up the highest density among Mediterranean regions. Behind this group, at a median level(20-25 territories/100 km2) come Castilla y León, Navarra, Andalucía, Madrid, Aragón and La Rioja. The rest of the Spanish regions (in the Mediterranean arch, Castilla-La Mancha and the Balearic and Canary Isles) do not reach the figure of 18 territories/100 km2. In terms of birds per kilometre, Extremadura comes second (3.7 birds/10 km), behind Cantabria (4.3) and ahead of Castilla y León (3.5) and Madrid (2.7). Broken down by provinces, the highest densities are recorded by Salamanca (8 birds /10 km), Segovia (4.7), Ávila (4.5), Cantabria (4.3), Cáceres (4.2) and Badajoz (3.2).

The fieldwork was coordinated and carried out by SEO volunteers and personnel of the Environment Board (Dirección General del Medio Natural) of the Regional council of Extremadura (Junta de Extremadura).

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