View please the text (En) dedicated to Short-toed Eagle in Extremadura /map/ which is posted by Javier Prieta on the Birds of Extremadura site.
Also on the Global Raptor Information Network website you can find the following paper:
• William S. CLARK, David FISHER, Brian FINCH, Bernd de BRUIJN and Itai SHANI, 2005 – Status of Beaudouin’s Circaetus beaudouini and Short-toed Snake-eagles Circaetus gallicus in Kenya // Bulletin of the African Bird Club, 12: 150-152. – (En).