Do boars compensate for hunting with higher reproductive hormones?

Area of Science:

• Wildlife Ecology
• Reproductive Physiology
• Animal Behavior

Background:

• The predation-stress hypothesis suggests predation risk negatively impacts reproduction via stress.
• However, stress can sometimes enhance mammalian reproductive potential.
• Wild boar (Sus scrofa) populations are increasing globally despite high hunting pressure.

Purpose of the Study:

• To investigate the physiological effects of hunting pressure on wild boar reproduction.
• To determine if the stress response is involved in earlier sexual maturity observed under hunting pressure.
• To compare steroid hormone levels in wild boars exposed to varying hunting pressures and social groupings.

Main Methods:

• Analysis of steroid hormone levels (cortisol and progesterone) in the hair of female wild boars.
• Comparison between populations experiencing high and low hunting pressure in northern Israel.
• Assessment of hormone levels based on whether females roamed alone or in groups.

Main Results:

• No hormonal signs of chronic stress (low cortisol) were found in hunted wild boars.
• Progesterone levels were significantly higher in females exposed to high hunting pressure.
• Females in groups had higher progesterone than solitary females, with no difference in cortisol.

Conclusions:

• Elevated progesterone associated with hunting may enhance reproductive potential in female wild boars.
• High hunting pressure does not necessarily impair reproduction through chronic stress in this species.
• Hormonal responses, rather than stress, might contribute to wild boar population growth despite hunting.