The present paper analyzes the changes in migration patterns of a Tibetan-style transhumance livelihood system for a period of 20 years in northwest Yunnan, China. Between 1984 and 2005, the average number of pastures for rotational use in the 12 investigated villages decreased from 6.2 to 3.9, and the average number of stops on the annual migration route decreased from 8.3 to 5.8. The number of days during which the animals depend on stall feeding and low-elevation shrubs increased from 231.3 to 270, while those spent in forest belts decreased by 32.6% and those in alpine rangelands by 25.5%. These changes have intensified the pressure on low-elevation ecosystems and grazing resources. Winter fodder supply, rather than carrying capacity based on overall grazing resources at all elevations, should be used to determine the scale of pastoral development. Encroachment of woody plants is a major cause of alpine rangeland degradation, which used to be unjustifiably attributed to a growing livestock population. Reintroduction of traditional management tools such as burning can effectively increase the area of available rangeland resources and curb localized degradation processes by evening out grazing pressure.