Description Alpine chough

red-billed chough (left) has deeper wing fingers , tail wedge in flight alpine (on right), , wings extend or beyond tail tip when standing.

the adult of nominate subspecies of alpine chough has glossy black plumage, short yellow bill, dark brown irises, , red legs. smaller red-billed chough, @ 37–39 centimetres (15–15 inches) length 12–14 cm (4.7–5.5 in) tail , 75–85 cm (30–33 in) wingspan, has proportionally longer tail , shorter wings relative. has similar buoyant , easy flight. sexes identical in appearance although male averages larger female. juvenile duller adult dull yellow bill , brownish legs. alpine chough unlikely confused other species; although jackdaw , red-billed chough share range, jackdaw smaller , has unglossed grey plumage, , red-billed chough has long red bill.

the subspecies p. g. digitatus averages larger nominate form, weighing 191–244 g (6.7–8.6 oz) against 188–252 g (6.6–8.9 oz) p. g. graculus, , has stronger feet. in accordance bergmann s rule, predicts largest birds should found higher elevations or in colder , more arid regions. extremities of body, bill , tarsus, longer in warmer areas, in line allen s rule. temperature seemed important cause of body variation in alpine chough.

the flight of alpine chough swift , acrobatic loose deep wing beats. high manoeuvrability accomplished fanning tail, folding wings, , soaring in updraughts @ cliff faces. in flight, can distinguished red-billed chough less rectangular wings, , longer, less square-ended tail.

the rippling preep , whistled sweeeooo calls of alpine chough quite different more typically crow-like chee-ow vocalisations of jackdaw , red-billed chough. has rolling churr alarm call, , variety of quiet warbles , squeaks given resting or feeding birds. in study of chough calls throughout palearctic region found call frequencies in alpine chough showed inverse relationship between body size , frequency, being higher-pitched in smaller-bodied populations.