The Saker (Falco cherrug Gray, 1834) is a large falcon species with the gyrfalcon (Falco rusticolus) being its closest relative. Earlier the species was split into more subspecies, however only two of them are recognised by ornithologists today:
- Falco cherrug cherrug ranges from Europe and from River Jenisei to Altai Mountains, China and North Mongolia;
- Falco cherrug milvipes can be found in the southern parts of Central Asia.
Saker is a brown buzzard-sized but slimmer bird of prey. Its body length varies between 45-55 cm and wingspan is 105-130 cm. Males weighs 730-990g, females 970-1300g. Females are bigger than males; however the difference is not as obvious as it can be noticed by Peregrines. Adults are yellowish brown on the back, head is light cream-coloured, sometimes almost white. Moustache is narrow, less distinct. White breast is typical for adults with brown spots that densify toward the belly. Cere and legs are yellow. Altogether adults are lighter coloured than young birds.
Just fledged young Sakers are also brown, but the spots on the breast and belly are denser merging into stripes. Moustache is more distinct and darker than on adults and head is darker as well. Cere and legs are light blue starting to become yellow only from the second year. Altogether juveniles are darker than adults.
In flight, Sakers recall the other large falcon species living in Hungary, the Peregrine, however wingtips of Sakers are less pointed and underwing coverts are darker creating a well visible contrast to primaries, which cannot be found on Peregrines that have similarly coloured underwing coverts and primaries.