Video report from ITV News Meridian reporter Richard Slee
The 1000-year-old tradition of 'pannage' is well underway in the New Forest this year.
It's a medieval form of forest management, using pigs to clear away the acorns that litter the forest floor.
Clearing those acorns keeps the forest's other residents, cattle and ponies in particular, out of harms way.
What is 'pannage'?
Pannage is a practice that began under William the Conquerer when he founded the New Forest in 1079.
The pigs are released by New Forest commoners (local people with rights over the forest attached to their land) to clear the ground of acorns, beechmast and other nuts from the forest floor.
Why is pannage necessary?
As the pigs graze and clear the forest floor, they are actually protecting the forest's other residents from danger.
Green acorns are a particular threat as they are poisonous the horses, ponies and cattle that roam the forest all year round.
But they make a sweet treat for the pigs as it's thought they're able to spit out the poisonous bits.
How does it work?
Pigs are not normally allowed to roam the forest freely, so commoners with pigs have to keep them on small holdings on their lands.
But when pannage season begins, up to 600 pigs and piglets are released into the woodland at anyone time.
As many as 6,000 pigs would be let loose during the 19th century, according to tourist group Go New Forest.
There aren't specific breeds of New Forest pig, but they do have to meet the criteria of having a nose ring to be allowed out.
This stops them digging and potentially damaging the forest floor, but still allows them to pick the nuts and acorns they are supposed to.