Breeding Alpine chough

egg, collection museum wiesbaden



eggs vary cream buff light-green, , have brown speckles.

the alpine chough socially monogamous, showing high partner fidelity in summer , winter , year year. nesting typically starts in may, , non-colonial, although in suitable habitat several pairs may nest in close proximity. bulky nests composed of roots, sticks , plant stems lined grass, fine twiglets or hair, , may constructed on ledges, in cave or similar fissure in cliff face, or in abandoned building. clutch 3–5 glossy whitish eggs, averaging 33.9 24.9 millimetres (1.33 in × 0.98 in) in size, tinged buff, cream or light-green , marked small brown blotches; incubated female 14–21 days before hatching. chicks hatch dense covering of natal down, in contrast of red-billed chough naked, , fledge in further 29–31 days hatching. young birds fed both parents, , may fed other adults when have fledged , joined flock. breeding possible in high mountains because chough eggs have relatively fewer pores of lowland species, , lose less water evaporation @ low atmospheric pressure. embryos of bird species breed @ high altitude have haemoglobin genetically determined high affinity oxygen.

in western italian alps, alpine chough nests in greater variety of sites red-billed chough, using natural cliffs, pot-holes , abandoned buildings, whereas red-billed uses natural cliffs (although nests in old buildings elsewhere). alpine chough lays eggs 1 month later relative, although breeding success , reproductive behaviour similar. similarities between 2 species presumably arose because of same strong environmental constraints on breeding behaviour.

a study of 3 different european populations showed mean clutch size of 3.6 eggs, producing 2.6 chicks, of 1.9 fledged. adult survival rate varied 83 92%, no significant difference detected between males , females. survival of first-year birds was, @ 77%, lower of adults. availability or otherwise of human food supplied tourist activities did not affect breeding success.