Age- and sex-dependent vigilance behaviour modifies social structure of hunted wild boar populations

Abstract

Abstract Context Human activities in general, and hunting in particular, often have significant impacts on the behaviour of wildlife through the anti-predator behaviours they evoke. Wild boar populations are rapidly expanding worldwide and their population densities are increasing. Aims To examine hunting effects in combination with different land-use factors on the behaviour and social structure of wild boars (Sus scrofa) in Israel. Specifically, to examine differences in vigilant behaviour and social structure in agricultural areas (hunting permitted) and nature reserves (hunting prohibited). Methods Motion-triggered cameras were installed to record wild boars’ social structure and vigilance behaviour along movement trails. Age and sex of individual wild boars were identified, as were the size and structure of their social groups, and hunting in each of the studied areas was quantified. Key results Results indicated significant differences in the vigilance behaviour of wild boars between agricultural areas and nature reserves. In agricultural areas, adult females were significantly more vigilant (P < 0.001) compared with adult males (P = 0.150). Additionally, in these areas there were significantly more adult males and fewer females leading family groups (P < 0.001). Furthermore, male yearlings were significantly more vigilant in agricultural areas (P < 0.001) compared with female yearlings (P = 0.164). Male yearlings tended to roam significantly more with family groups in agricultural areas compared with nature reserves, where they tended to roam alone or in groups (P = 0.029, P = 0.035). Conclusions These results indicate social and behavioural differences in wild boars between agricultural areas and nature reserves, suggesting that hunting may have a substantial impact on their social structure and behaviour. Implications Overall, the findings support the behavioural and social consequences of human hunting. Long-term implications of altered behavioural and social responses should be considered in management and conservations strategies. For instance, the high proportion of male yearlings in family groups in agricultural areas in autumn (October–December, mating season) may offer young males early access to reproductive females, even within the same social group. This may eventually lead to an increase in the reproductive potential of female wild boars.