Police have been called in after the guga hunters of Ness, who scale gigantic sea stacks off the Outer Hebrides in annual pursuit of the sea birds, received death threats.
Animal activists have allegedly targeted the hunters over the “harvest” of the young gannets when up to 2,000 birds are killed at Sula Sgeir, a rocky island off Ness, Lewis, every August.
The traditional 400-year-old hunt, where birds are clubbed, decapitated and held over a fire before being preserved in salt, has drawn increasing criticism in recent years.
Now, threatening phone calls have allegedly been made to a number of men involved in the hunt, with Police Scotland now investigating.
The calls were made from the south-east of England, it is understood.
The Scottish SPCA has led calls for the “barbaric” hunt for the birds to be banned.
A spokesman for the animal charity said: “We accept that maybe 150 to 200 years ago the guga formed part of the staple diet of the islanders but that is certainly not the case today.
“Yet, they are still using the same methods that were used all those years ago.
“The suffering starts before any attempt to kill takes place because the chicks are hauled from cliff tops using nooses attached to long poles, which in itself will terrify the birds.
“They are then struck on the head with a heavy implement until dead.”
While some birds may be killed with one or two blows, most will likely be struck several time, the spokesman added.
He continued: “It is a barbaric and inhumane practice that causes necessary suffering to thousands of young gannets a year.”
The island has a special exemption from the 1954 ban on hunting seabirds on cultural grounds.
Every year, a group of ten men sails 40 miles from Lewis to Sula Sgeir and spend two weeks hunting the young. The birds, said to taste like salty goose or fishy beef, are considered a delicacy to some with each bird reportedly fetching up to £16.
Guga hunters, who returned this year’s haul last week, claim they are protecting the history of the island with supporters pointing to similar practices occurring in Iceland and the Faroe Islands.
The investigation comes after the Moffat sheep race was cancelled at short notice last month after 80,000 people signed a petition against the display.
Dumfries and Galloway Council licensed the event in line with other performing animal shows with organisers unable to meet demands.