Degree of social isolation affects behavioural and vocal response patterns in dwarf goats ( Capra hircus)

Abstract

Separation from the group presents a serious challenge for social animals. This stressful and disagreeable situation can impair animal welfare and may have an undesirable impact on experimental data in scientific studies. In the present study, we observed whether different degrees of social isolation induced different behavioural and vocal responses in a gregarious animal species, the dwarf goat ( Capra hircus). For this study, 48 juvenile female goats were individually isolated either completely (alone in a pen in a separate building from conspecifics, n = 24) or partially (alone in a pen adjacent to their home pen with acoustic and olfactory contact, n = 24) on six consecutive days for 30 min at a time. During each isolation session, both behaviour (locomotion, standing, lying, rearing and jumping) and vocalisation (high bleats and low bleats) were recorded. High bleats were subjected to sound analyses to identify duration, peak frequency, pureness and entropy. The data analysis for all parameters was done for three periods of 5 min each, i.e., start, middle and end, for every isolation session. We found significant effects of the degree and period of isolation on both behaviour and vocalisation. Completely isolated animals were less active, showed lower rates of rearing and a fewer high bleats than partially isolated animals. In addition, they emitted high bleats with a more pronounced pureness and diminished randomness. Altogether, these behavioural reactions could be attributed to the perceived emotional distress associated with isolation. In the case of partial isolation, however, the permanent sensory feedback from conspecifics in adjacent pens facilitated an active response pattern (e.g., higher rates of locomotion, rearing, jumping and high bleats) and motivated efforts to restore social contact. Though most individuals did show changes in their behaviour during each isolation session, they did not become habituated after repeated isolation sessions. Consequently, social isolation should either be avoided completely or only applied in exceptional cases (e.g., essential veterinary treatments), and if possible, acoustic and olfactory contact should be allowed with conspecifics to provide social support.