The Mediterranean Peregrine Falcons that breed on the Rock of Gibraltar depend heavily on migrant birds at particular times of the year. This is one of those times. Many finches - Chaffinches, Greenfinches, Goldfinches, Linnets and Serins - are now flying south. The Peregrines wait for them in mid-air and dive at the vulnerable migrants.
The high density of Peregrines means they often invade each other's air space, leading to spectacular mid-air quarrels (above and below). They are so concentrated in finding the migrant flocks that they get close to the observer sitting on the cliff edge (below).See also posts of 9th and 14th February...