Table 3. The approach-leave interaction frequencies and Hinde Index between Xiaoci and Xiaohei during the first year after birth.

Age (month)	Obs. days	calf approach mother(times/h)	mother approach calf(times/h)	calf leave mother (times/h)	mother leave calf (times/h)	HI index
1	16	0.2 ± 0.98	0.78 ± 2.62	1.75 ± 264	0.47 ± 1.85	-0.58
2	22	0.67 ± 1.96	1.57 ± 3.65	1.71 ± 2.11	1.38 ± 1.69	-0.25
3	18	0.89 ± 2.12	1.3 ± 2.34	1.82 ± 2.28	1.21 ± 2.62	-0.20
4	21	0.89 ± 1.44	1.2 ± 2.48	1.43 ± 2.72	0.91 ± 1.17	﹣0.19
5	20	1.1 ± 1.82	1.22 ± 2.65	1.71 ± 2.53	1.22 ± 1.12	-0.11
6	24	0.89 ± 1.87	0.98 ± 1.78	1.6 ± 2.89	1.35 ± 1.98	-0.07
7	24	0.98 ± 2.32	0.31 ± 2.12	1.24 ± 1.56	2.2 ± 3.21	0.17
8	22	0.65 ± 2.75	0.43 ± 1.56	1.12 ± 1.91	2.32 ± 1.45	0.26
9	23	0.43 ± 1.87	0.32 ± 1.32	0.41 ± 1.45	1.89 ± 2.67	0.39
10	23	0.35 ± 1.12	0.18 ± 1.21	0.64 ± 1.87	2.17 ± 3.45	0.43
11	20	0.26 ± 1.38	0.24 ± 1.31	0.78 ± 1.45	1.78 ± 3.12	0.21
12	17	0.35 ± 1.32	0.12 ± 1.67	0.52 ± 0.35	1.67 ± 2.65	0.50