Thursday, 29 December 2011
THE HOBBY IN EXTREMADURA (2009-2010)
In 2009-2010 SEO/BirdLife organized the first ever survey of nine diurnal woodland raptors (Palomino and Valls, 2011), the Hobby (Falco subbuteo) being one of the target species. Its estimated Extremadura population came out as 170 territories (range 140-200). This represents only 3.9% of the Spanish total (4410 territories), way below the figures for Castilla y León (1460) Galicia (650), Castilla-La Mancha (590) and Aragón (530). Extremadura's mean density is 0.4 territories per 100 km2, below the national mean of 0.9.
Broken down by provinces, Badajoz holds 120 territories and Cáceres 50. The densities (0.55 in Badajoz and 0.26 in Cáceres) are among Spain's lowest. In all it was detected in 7% of the 10k grids surveyed by means of lookout points (6% in Badajoz and 10% in Cáceres).
The Hobby has a patchy range in Extremadura, with the highest likelihood of sightings, and ipso facto the greatest abundance, in the eastern half of Badajoz and the southeast corner of Cáceres. There are also smaller population clusters in the Vegas del Guadiana and the centre of Badajoz. The map hardly predicts Hobby presence in pinewoods of the central mountain range, though there is in fact known to be a small population there. In general, the Hobby chooses in Spain cooler, low-rainfall, low-altitude areas with varied farmland scenery and nearby wetlands.
Car transects are not really a very suitable censusing method for this shy, retiring raptor. In Extremadura only 2 Hobbies were seen on average every thousand kilometres, matching exactly the average figure for Spain as a whole. It was detected in 7% of the surveyed 10k grids (3% in Badajoz and 11% in Cáceres). Of all the nine species studied, this species shows the lowest bird-per-kilometre figure both in Extremadura and Spain as a whole.
The Hobby's trend in Spain is unknown. The Spanish breeding birds monitoring project SACRE is not really suitable for surveying such a scarce, low-profile species. It shows a decline of 56% from 1998 to 2010 but this needs to be taken with a pinch of salt.
Very little is known about the Hobby in Extremadura, so these findings are quite revealing. For example, this study threw up the first probable breeding record in such a heavily birded site as Monfragüe. Nonetheless the models obtained for this raptor in Spain are pretty inaccurate due to the low number of contacts. All the abovementioned information now needs to be confirmed in the field, especially in Badajoz, which records higher population figures than Cáceres even though the species has been observed 2-3 times less in the former province.
The fieldwork was coordinated and carried out by SEO volunteers and staff of the Environment Board of the Regional Council of Extremadura.
Source
- Palomino, D., y Valls, J. 2011. Las rapaces forestales en España. Población reproductora en 2009-2010 y método de censo. SEO/BirdLife. Madrid. [PDF]
