Here you can acquaint yourself with the work on the wintering of Short-toed Eagle and Booted Eagle in Spain:
• José Enrique Martínes y José Antonio Sánchez-Zapata, 1999 – Invernada de Aguililla Calzada (Hieraaetus pennatus) y Culebrera Europea (Circaetus gallicus) en España [Wintering of Booted Eagles and Short-toed Eagles in Spain] // Ardeola 46 (1): 93-96 – 
(Es) (source – Ardeola website).
…and with the abstract of an article about Greek Short-toed Eagles:
• D.E. Bakaloudis, C.G. Vlachos, G.J. Holloway, 1998 – Habitat Use by Short-Toed Eagles Circaetus gallicus and Their Reptilian Prey During the Breeding Season in Dadia Forest (North-Eastern Greece) // Journal of Applied Ecology, Vol. 35, No. 6: 821-828 (En) /map/ (source – the JSTOR database).