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10 July 2013

Peregrine versus Barn Owl

Peregrine Falcons have been doing well in the past decade, following a crash in the population in the 70s due to pesticide poisoning. Their recovery has been complete thankfully and they are now spreading into areas where they have not been known to breed before, particularly at inland sites. They need a cliff ledge on which to nest and quarries, church steeples, castles and other large structures have all been used in areas where no natural cliffs exist.

This castle site in Duhallow has long had Barn Owls present, but a search of the area yesterday also revealed the presence of a Peregrine Falcon. Although no bird was seen, the feathers and pellets were found under a roost site on the outer castle walls.

Moulted feathers and 'whitewash' below the castle walls (M.O'Clery).

Two Peregrine pellets,  containing the remains of birds' bones (bird bones are usually hollow) and feathers, very different from the larger, slightly glossy black pellets of Barn Owls which usually contain the fur and bones of small mammals (M.O'Clery).

Peregrine feathers and pellets, Duhallow (M. O'Clery).
(click on any of the images for a closer look)

Although Peregrines and Barn Owls can share the same site, the arrangement seems to be an uneasy one, and we know of cases in Ireland of Barn Owls disappearing from traditional sites shortly after the Peregrines moved in. Peregrines are a powerful and aggressive species and have little tolerance for other birds of prey near their nest site. In the Barn Owl's favour is the fact that they fly and hunt at night when any Peregrine at the site is tucked away at its roost.