The study of nest-site preferences in Eleonora’s falcon Falco eleonoraethrough digital terrain models on a western Mediterranean island

This study addresses nesting-site preferences in Eleonora’s falcon Falco eleonorae by means of geographic information systems and high-quality high-resolution digital terrain models (DTMs). A small western Mediterranean archipelago (Columbretes Islands) with a colony of 34 pairs was chosen as a case study. Overall, 21 grid variables obtained from DTM were considered of which 12 showed a signi.cant e.ect. Four of them were topographic (i.e. elevation, X-axis aspect, slope and curvature), four climatic (i.e. wind exposure, solar insolation, solar radiation and radiation index), three anthropogne (visibility of lighthouse beam, visibility of antropic zones and distance to antropic zones) and one biotic (vegetation cover). Falcon nests were placed on pixel cells with lower average insolation and radiation than cells without nests, but had higher values of wind exposure. Nests were built on concave sites mainly with an easterly facing aspect and steep slopes. Falcons were shown to respond to human presence as all antropic variables considered had a signi.cant e.ect. The results have a number of management and conservation implications, because the knowledge of nesting preferences of the species allows the proper design of sanctuaries and an appropriate human use of these areas.

G. Urios and A. Martinez-Abrai, J Ornithol (2006) 147: 13-23