No response yet from the Chincoteague Fire Company on the number of adult males and females on the island.
The herd would need at least 100 females to produce 100 foals.
That leaves 50 males out of a herd of 150, the maximum number of ponies allowed by FWS, for a sex ratio two mares for each stallion.
Abnormal sex ratios are usually seen in herds treated with PZP, a byproduct of the effort to sterilize the mares, but in the case of the Chincoteague herd, it’s probably intentional.
Western Horse Watchers Association 