The bar-headed goose (Anser indicus) is a type of goose that lives in wetland areas in Central Asia. It has a light grey body, broad wings, and a white face and neck. Its name comes from the two stripes (or "bars") of dark feathers that wrap around the back of its head. Like other geese, its feet are webbed. They can get up to 2.5 feet long and weigh 6.5 pounds. They eat mainly grass, wheat, barley and rice.
The main physiological challenge of bar-headed geese is getting oxygen from thin air to their aerobic muscle fibres so they can fly at high altitudes. Flight is very metabolically costly at high-altitudes because birds need to flap harder in thin air to generate lift.
Studies have found that bar-headed geese breathe more deeply and efficiently under low oxygen conditions, which serves to increase oxygen uptake from the environment. The haemoglobin of their blood has a higher affinity for oxygen compared to low-altitude geese.
Bar-headed geese have a slightly larger wing area for their weight than other geese, which is believed to help them fly at high altitudes. Birds at high-altitude still need to flap harder than lowland birds.
- BirdLife International (2004). Anser indicus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006.
- Altshuler, D.; Dudley, R. (6 January 2006). "The physiology and biomechanics of avian flight at high altitude". Integrative and Comparative Biology. 46 (1): 62–71. doi:10.1093/icb/icj008. PMID 21672723. Retrieved 20 October 2015. CS1 maint: discouraged parameter (link)
- Milsom, William K.; Scott, Graham (2008). "Respiratory adaptations in the high flying bar-headed goose". Comparative Biochemistry and Physiology C. 148 (4): 460. doi:10.1016/j.cbpc.2008.10.047.
- Liu, X.-Z.; Li, S.-L.; Jing, H.; Liang, Y.-H.; Hua, Z.-Q.; Lu, G.-Y. (2001). "Avian haemoglobins and structural basis of high affinity for oxygen: Structure of bar-headed goose aquomet haemoglobin". Acta Crystallographica Section D. 57 (6): 775–783. doi:10.1107/S0907444901004243.
- Lee, S.Y.; Scott, G.R.; Milsom, W.K. (2008). "Have wing morphology or flight kinematics evolved for extreme high altitude migration in the bar-headed goose?". Comparative Biochemistry and Physiology C. 148 (4): 324–331. doi:10.1016/j.cbpc.2008.05.009.
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