The Saker Falcon is a large hierofalcon, larger than the Lanner Falcon and almost as large as Gyrfalcon at 47-55cm length with a wingspan of 105-129cm. Its broad blunt wings give it a silhouette similar to Gyrfalcon, but its plumage is more similar to a Lanner Falcon's.
Saker Falcons have brown upperbellies and contrasting grey flight feathers. The head and underparts are paler brown, with streaking from the breast down. Males (called sakrets in falconry) and females are similar, as are young birds, although these tend to be a duller brown. The call is a sharp kiy-ee.
Adults can be distinguished from the similar Lanner Falcon since the Lanner is blue-grey above with a reddish back to the head. However, juveniles of the two species can be very similar although the Saker Falcon always has a uniformly buff top of the head with dark streaks, and a less clear pattern on the sides of the head.
A further complication is that some Asian birds have grey barred upperparts; these must be separated from Lanner on size, structure, and a weaker moustache stripe. Saker Falcons at the northeast edge of the range in the Altay Mountains are slightly larger, and darker and more heavily spotted on the underparts than other populations. These, known as the Altai Falcon, have been treated in the past either as a distinct species "Falco altaicus" or as a hybrid between Saker Falcon and Gyrfalcon, but modern opinion (e.g. Orta 1994) is to tentatively treat it as a form of Saker Falcon, until comprehensive studies of its population genetics and ecology are available.
Unfortunately, this species belongs to the close-knit hierofalcon complex. In this group, there is ample evidence for rampant hybridization and incomplete lineage sorting which confounds analyses of DNA sequence data to a massive extent; molecular studies with small sample sizes can simply not be expected to yield reliable conclusions in the entire hierofalcon group. The radiation of the entire living diversity of hierofalcons seems to have taken place in the Eemian interglacial at the start of the Late Pleistocene, a mere 130,000-115,000 years ago; the Saker Falcon represents a lineage that expanded out of northeastern Africa into the interior of southeastern Europe and Asia, by way of the eastern Mediterranean region.
Probably the saker falcon (Kerecsensólyom) was the Hungarian mythological bird, the Turul.
Information From Wikipedia.