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It is resident around lakes and marshes in the high Andes, usually well above 3000 m. It is largely terrestrial and avoids swimming except in emergencies.
This heavily built bird has a tiny pink bill and white plumage except for black in the wings and tail. The female is similar to the male, but is smaller.
The Andean goose is a grazing species, eating grasses. It nests on the ground in a bare scrape near water, laying 6-10 eggs. It is territorial in the breeding season, but otherwise forms small flocks.
Physiology and Hemoglobin Adaptation
Andean geese (C. melanoptera) have developed a mutation in their hemoglobin that has led to a vast increase in hemoglobin-oxygen affinity. More specifically, Hiebl et al. found that C. melanoptera has developed mutations that lead to five amino-acid substitutions in the alpha-chain and five substitutions in the beta-chain of their hemoglobin.  A particular substitution the in C. melanoptera beta-chain has led to the elimination of a Van der Waals interaction between the alpha-chain and the beta-chain. This has destabilized the T-state (the deoxygenated state of hemoglobin), which has led to a higher affinity for being in the R- state (oxygenated state of hemoglobin). Overall, this mutation increases the hemoglobin-oxygen affinity of C. melanoptera.
- BirdLife International (2012). "Chloephaga melanoptera". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Hiebl, I and Braunitzer, G and Schneeganss, D (1987). "The primary structures of the major and minor hemoglobin-components of adult Andean goose (Chloephaga melanoptera, Anatidae): the mutation Leu----Ser in position 55 of the beta-chains". Biological Chemistry Hoppe- Seyler 368 (12): 1559–1569.
- Storz, Jay; Hideaki Moriyama (June 2008). "Mechanisms of Hemoglobin Adaptation to High Altitude Hypoxia". High Altitude Medicine and Biology 9 (2): 148–157. doi:10.1089/ham.2007.1079. PMC 3140315.