Soaring Flight in the Eleonora’s Falcon (Falco eleonorae)

Eleonora’s Falcon (Falco eleonorae)breeds in the Mediterranean region and is highlyadapted for catching small birds on passage migrationbetween Eurasia and their African winter quarters,which they feed their young.We studied glidingflight behavior of Eleonora’s Falcon at a breeding colonylocated on a small island southwest of Sardinia,Italy. Gliding and soaring flight performance wasmeasured using an optical range finder and evaluatedagainst flight mechanical theory. The male falcondoes the majority of hunting and usually sets offfrom the colony to hunting areas located at high altitudeover the open sea to catch prey. To lower thecost of transport and maximize the energy gain fromhunting, we show that the birds use vertical windsfor soaring when available. The occurrence of risingair changes with wind direction. At north-northwesterlywinds (on-shore), slope lift is available outsidethe nesting cliffs, and at south-southeasterlywinds thermals that form over the island drift outover the sea. Our observations demonstrated theflexibility of flight behavior in relation to the windsituation, and birds thereby make full use of availablesoaring conditions

Mikael Rose and Anders Hedenstrom, The Auk 119(3):835-840, 2002