Sunday, July 31, 2011

Raptor Migration in late July

We saw the last Black Kites Milvus migrans migrating north in mid-June. Now they're back, heading south for Africa with this year's youngsters!

For a few days now small groups of Black Kites have been crossing the Strait of Gibraltar as they head for the tropical African savannas

But yesterday evening, around 6pm we saw a big "rush" of birds over the Rock of Gibraltar. My friend Mario Mosquera estimated 1500 birds in the flock, a taste of things to come. With westerly winds these birds drift over Gibraltar from where they gain height to start the crossing. If the wind is too strong some turn back, often having already started over the sea, and try the next day.

Most of yesterday's birds were juveniles, birds that have been born this spring. You can tell them by the pale, rufous, plumage and the fresh wing and tail feathers. Breeding among the Iberian birds is timed to coincide with the spring abundance of food. The Iberian adult Black Kites arrive in February and early March. It is these birds, and their young, that are now leaving to avoid the summer drought. Their arrival in sub-Saharan Africa will coincide with the onset of the summer rains there.

Not everything is leaving after breeding. Eleonora's Falcons Falco eleonorae are just arriving in the area from their wintering grounds on the island of Madagascar. These rare and elegant falcons breed in remote islets and unfrequented coastal sites across the Mediterranean and the Atlantic coast of North Africa. They arrive late for a reason. Their young will hatch in September and will be fed on the millions of small migrating birds that will then be heading for Africa. It is a wonderful example of a perfectly tuned specialised strategy. It's not easy to find these birds on migration so it was a treat to see this female (above and below) yesterday at Europa Point.

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