Seasonal differences of the Milu's home range at the early rewilding stage in Dongting Lake area, China

The study of home range utilization of rewilded animals is important for informed reintroduction management. Sixteen Milu adult individuals (5♂11♀) were reintroduced from Jiangsu Dafeng Milu National Nature Reserve to Hunan East Dongting Lake National Nature Reserve on February 28, 2016, out of which 11 Milu individuals (1♂10♀) were wearing GPS satellite tracking collars. Subsequently, with the aid of GPS collar technology, combined with on-ground tracking observations, we tracked the reintroduced Milu for one year from March 2016 to February 2017. We used the dynamic Brownian Bridge Movement Model to estimate the individual home range of the 10 rewilded Milu (1♂9♀, 1 female individual was eliminated because its collar fell off) and seasonal home range of 5 rewilded female Milu (all tracked for up to one year). 95% level represented the home range, and 50% level represented the core areas. Temporal variation in normalized difference vegetation index were used to quantify changes in food availability. We also quantified resource use of rewilded Milu by calculating the selection ratio for all habitats within their core areas. The results showed that: (1) a total of 52,960 coordinate fixes were collected; (2) during the early stage of rewilding, the average home range size of the rewilded Milu was 17.62 ± 3.79 km2 and the average core areas size was 0.77 ± 0.10 km2; (3) the annual average home range size of the female deer was 26.08 ± 5.21 km2 and the annual average core areas size was 1.01 ± 0.14 km2 at the early stage of rewilding; (4) during the early stage of rewilding, the home range and core areas of the rewilded Milu were significantly affected by season, and the difference between summer and winter was significant (home range: p = 0.003; core areas: p = 0.008); (5) home range and core areas of the rewilded female deer in the Dongting Lake area in different seasons showed significant negative correlation with NDVI (home range: p = 0.000; core areas: p = 0.003); (6) Most rewilded female Milu showed a high preference for farmland in all seasons except winter, when they focused on using lake and beach. The home range of the rewilded Milu in the Dongting Lake area at the early stage of rewilding experienced significantly seasonal changes. Our study reveals seasonal differences in the home ranges of rewilded Milu and the resource use strategies of individual Milu in response to seasonal changes. At last, we put forward the following management recommendations: (1) to establish habitat islands; (2) to implement community co-management; (3) to reduce human disturbance; (4) to strengthen population monitoring for formulating species conservation plans.