The Dalmatian pelican (Pelecanus crispus) is the largest member of the pelican family, and perhaps the world's largest freshwater bird, although rivaled in weight and length by the largest swans. They are elegant soaring birds, with wingspans rivaling those of the great albatrosses, and their flocks fly in graceful synchrony. With a range spanning across much of Central Eurasia, from the Mediterranean in the West to the Taiwan Strait in the East, and from the Persian Gulf in the South to Siberia in the North, it is a short-to-medium-distance migrant between breeding and overwintering areas. No subspecies are known to exist over its wide range, but based on size differences, a Pleistocene paleosubspecies, P. c. palaeocrispus, has been described from fossils recovered at Binagady, Azerbaijan. This huge bird is by a slight margin the largest of the pelican species and one of the largest living flying bird species. The somewhat similar-looking great white pelican broadly overlaps in size but has greater size sexual dimorphism: female great whites can be noticeably smaller than female Dalmatians but male individuals of the two species are essentially the same size and weight. However, the Dalmatian differs from this other very large species in that it has curly nape feathers, grey legs and silvery-white (rather than pure white) plumage. In winter, adult Dalmatian pelicans go from silvery-grey to a dingier brownish-grey cream colour. Immature birds are grey and lack the pink facial patch of immature white pelicans. The loose feathers around the forehead of the Dalmatian pelican can form a W-like-shape on the face right above the bill. In the breeding season it has an orange-red lower mandible and pouch against a yellow upper mandible. In winter, the whole bill is a somewhat dull yellow. The bill, at 36 to 45 cm (14 to 18 in) long, is the second largest of any bird, after the Australian pelican (Pelecanus conspicillatus). The bare skin around the eye can vary from yellow to purplish in colour. When the Dalmatian pelican is in flight, unlike other pelicans, its wings are solid grayish-white with black tips. It is an elegant soaring bird. When a whole flock of Dalmatian pelicans is in flight, all its members move in graceful synchrony, their necks held back like a heron's.