The Saker falcon is one of Bulgaria's most vulnerable birds, already on the brink of extinction. At present, there is not a single registered nesting couple here, despite the many years of targeted efforts by the BSPB and by other nature conservation organisations to monitor the species and its historic habitats.
The BSPB has worked for many years to preserve the species, by integrating direct and indirect nature conservation measures. These include the following: placing of artificial nest-boxes in habitats which are suitable for the species, development and implementation of agricultural practices, working with the institutions to prevent crime against wildlife and to ensure legislative improvements, informing the public about the problems of the species and seeking of active public support, development of a management plan for the species, etc.
DESCRIPTION OF THE SPECIES
The Saker falcon is the largest falcon in Bulgaria and the second largest in the world, next to the Gyrfalcon, to which they are closely related.
The species is divided in two sub-species:
• Falco cherrug cherrug - breeding from Europe as far as the Altai Mountains, China and Northern Mogolia.
• Falco cherrug milvipes – breeding in the southern parts of Central Asia.
The Saker falcon is as large as the Common buzzard, but has a more elegant body. It's 45 to 55 cm long and has a wingspan of 105 to 130 cm. The females are larger than the males but the distinction is not as obvious as in some other falcon species.
The adult birds have brown upper-bellies, and pale, sometimes even white, heads. Their malar stripes are narrow, usually sharpened downwards and nearly indistinguishable in some cases. The adults have light coloured breast areas with oval spots. The ceres and the tarsi are yellow in colour. Usually, the adult birds are paler than the juveniles.
The juveniles are also brown, but the underparts are more densely streaked. The malar stripes are darker and distinguishable, and the head is also darker. The tarsi and the ceres are light bluish and become yellow during the second year.
In flight, the Saker falcon resembles the Peregrine falcon to some extent, but the wing tips of the Saker are less pointed and the underwings are darker, creating a visible contrast with the primary feathers. Unlike the Peregrine falcon, the Saker's undertail is without spots.
The Saker falcon prefers steppes and forest steppes, as well as areas with large pastures inhabited by ground squirrels, shrews and other rodent species. Like other falcon species, the Saker falcon does not build its own nests but takes the nests of other species - Ravens, Hooded crows, Common buzzards, and, occasionally, Imperial eagle, White stork, Gray heron and Large cormorant. Usually, it nests on rocks in niches or on rock shelves, but can occupy the nests of species nesting on rocks.
In some countries the species uses readily artificial nest boxes placed on high-voltage pylons. This new strategy has allowed the Saker falcon to nest in new areas previously inaccessible to it because of unsuitable brooding sites.
The Saker falcon prefers nesting locations which are difficult to access and which afford good visibility to the hunting territory. The mating period begins very early in spring - by late February or early March, depending on the weather. At the beginning of this period, the birds perform beautiful mating flights. They are very aggressive around the nest during this time of year and would attack all other raptors, including large eagle species. Having established themselves in a place, however, they can be very tolerant to other raptors. Peregrine falcons nesting on the same rock with Saker falcons, at a distance of less than 500 m apart, have been observed.
Usually, the female lays 3-5 eggs by mid or late March. The brooding lasts for approximately 32 days. The young birds acquire full feathers in 6 weeks. The females can breed after the first year, while the males mature sexually after the second year. The Saker falcons pair for life.
Most pairs prefer souslik as their prey. The Saker falcon may also feed on other small rodents, and, also, on average-sized and small birds. In early spring, when sousliks are still not active, migrating birds may form a large part of the Saker falcon's menu. Sometimes, the birds from the pair hunt together. Frequently, the Saker falcon steals prey from other raptors.