Iberian birds winter in sub-Saharan Africa. The majority of those crossing at the Straits of Gibraltar in autumn are from the main European breeding grounds but a few also find their way to Cape St Vincent. Here, and elsewhere in the south-west, they can sometimes be seen circling high up with the flocks of Griffon Vultures which accumulate in October and November. Small parties can also be found resting at inland wetlands, such as the Barragem de Monte da Rocha near Ourique. The largest day count from my Budens vantage point is sixteen which demonstrates how much rarer it is than White Stork. Curiously, though, it outnumbers that species at this season in the extreme south-west.
The Black Stork is less sociable than its commoner relative with nests often as much as one kilometre apart. These are mostly near the tops of large trees but can be sited on cliff ledges or even in shallow caves. Pairs remain together over many seasons. Their pair-bonding greetings and displays are similar to those of White Storks’ although bill-clattering is unusual and mainly associated with aggressive excitement in the presence of an intruder. Three or four young are reared to fledging, after which the juveniles quickly become independent.
Black Stork Nest Camera
Unlike the rather mute White Stork, Blacks are surprisingly vocal with different whistling calls used at the nest and during displays, with a more prolonged piping hiss employed to deter an intruder. There is even said to be a thin, high-pitched flight call, although I have never heard this myself despite frequent encounters with the species in Turkey, where it was much more numerous.