Effects of plant phenology and solar radiation on seasonal movement of golden takin in the Qinling Mountains, China

The golden takin (Budorcas taxicolor bedfordi) is a large, forest-dwelling ungulate endemic to the Qinling Mountains, China. A recent study showed that golden takin move to different elevations depending on the season, remaining at high elevations in summer, intermediate elevations in winter, and at low elevations for short periods in spring and autumn. We proposed the following hypotheses: seasonal movement of golden takin is a response to a shift in vegetation phenology, which affects forage quality; and uphill movement of golden takin in winter is an adaptation to select areas with higher thermal energy. To test the 1st hypothesis we used relative phenological development derived from the normalized difference vegetation index time series to link seasonal shifts in vegetation phenology to movement patterns of golden takin. Golden takin descended to a low elevation with the greening of vegetation in early spring, ascended to a high elevation in late spring, and descended again in autumn as vegetation senesced. To test the 2nd hypothesis we compared thermal energy in the winter habitat with that in other areas of the home range, using the amount of solar radiation calculated by a solar radiation model. In winter, preference of the golden takin for exposed southern slopes at intermediate elevations correlated closely with areas of higher solar radiation. Our results indicate that solar radiation and vegetation phenology are critical factors in driving seasonal movement of golden takin.