Attributes / relations provided by
♦ 1del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.).
Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
♦ 2Variation in the diet of the viperine snake Natrix maura in relation to prey availability, Xavier Santos, Jacob González-Solís and Gustavo A. Llorente, ECOGRAPHY 23: 185192. Copenhagen 2000