Spain is fortunate to have the largest breeding population of Lesser Kestrels Falco naumanni in the Mediterranean region. Neighbouring Portugal is trying to increase the number of breeding birds by building artificial nesting walls such as the one in Castro Verde, Alentejo. But where do they go after breeding? Well many of them congregate in large roosts in South Africa. A total of approximately 60,000 lesser kestrels roost over around 20 different roost sites. A few years ago I visited the famous roost in De Aar, a sleepy town in the Northern Cape region of South Africa. De Aar usually hosts around 10,000 to 12,000 birds. In an age where alien plants are an increasing problem there are a few beneficial aliens, as the lesser kestrels choose to roost in imported Pine Trees planted in the grounds of the local hospital. Roughly a dozen trees will hold 1,000 kestrels each.
As the sun goes down a large flock of lesser kestrels starts to circle overhead. Gradually birds fly into the pine trees to settle down for the night. The birds are generally silent except when jostling for choice roosting spots. But the birds soon settle in for the night and the roost becomes quiet. This roosting behaviour is quite different to that of Amur falcons that also have large winter roosts in South Africa. A handful may even join the lesser kestrels in De Aar, though most choose sites dominated by Amur falcons. At Newcastle in Kwa-Zulu Natal 35,000 or more Amur falcons can be seen. They congregate very high up and only descend after dark. Amurs are very noisy, calling all the time and the noise continues even once the birds are in the roost trees.
Lesser kestrels leave their roost very early in the morning. Perhaps 50 or so birds at a time burst out of one tree in an explosion of falcons. By first light nearly all the birds have left to forage for insects in the surrounding veld until they return again in the evening. Amur falcons by contrast all leave the roost under cover of darkness, leaving the roost empty by sun-up.
Phil Perry – ABS life member