Wednesday 30 May 2012


A few weeks ago we spoke in this blog entry about the African odyssey of two satellite-tagged Extremadura Booted Eagles (Hieraaetus pennatus) from September 2011 to February 2012. Like the other tagged birds in other Spanish provinces our two Booted Eagles have now come home safe and sound and seem to have got down to the task of breeding. Their return journeys were as follows.

Luna (a female, No.5 on the map) left her stable wintering area in Mali on 16 March. After passing through Mauritania, Western Sahara and Morocco she crossed the Strait of Gibraltar on 1 April, thereafter returning more slowly to her breeding territory in Alburquerque (Badajoz), where she arrived on the 6th. In total a 2700 km journey in 21 days at an average of 130 km per day and the longest stages of 344 km and 323 km on 18 and 20 March, smack in the middle of the desert. Progress within Spain was much slower, with a maximum daily stint of 120 km. In 2012 she has built a new nest only 250 m from the one used in 2011, which fell down last winter (Ángel Sánchez, pers. com.). 

Valiente (male, No.6 on the map) kicked off his trip from Nigeria on 19 March, then passing through Niger, Mali, Algeria and Morocco, crossing the Strait on 2 April and arriving back in La Roca de la Sierra (Badajoz) on 7 April. A long journey of 3500 km in 20 days, at a mean speed of 175 km per day and the longest stages of 420 and 418 km on 21 and 24 March. The longest day journey made in Spain was only 95 km. This was the swiftest moving of the six birds and one of the two with the most distant wintering area.

If we look at the whole set of six tagged birds (two in Badajoz and Madrid and one each in Castellón and Ávila) we find that the spring homecoming journey did not follow the same route as the autumn outgoing one, which was further west in all cases. The start day varied from 1 to 20 March (mean date of 13 March), the Strait crossing from 30 March to 11 April (mean date of 4 April) and the arrival on the breeding territory from 4 to 26 April (mean date of 10 April). The total distance covered ranged from 2725 to 3530 km (mean of 3095 km), the duration from 17 to 51 days (28 mean) and the average daily speed from 70 to 175 km (mean 126). Barring one bird that made the trip in two stages, stopping for a time in one of its two wintering areas, the rest came back directly, moving more rapidly through Africa and slowing down upon entering the Iberian Peninsula.

More information on the SEO/BirdLife project website "La migración de las aves" (Bird Migration).