London, England (CNN) -- Birdies are normally seen as a golfer's best friend but at one course in Northern Ireland members are getting increasingly irritated by a certain feathered felon.
For the last few months, a large raven has been stalking Greencastle Golf Club in Donegal before swooping and flying off with people's balls.
Several players have witnessed the burglar at work while others have struck what they thought was an accurate shot only to arrive on the green to find no sign of their ball.
Billy McCaul, the golf club's office manager, says players are reporting stolen balls on a weekly basis.
"It started to happen about four months ago, when you had the odd comment about a ball being taken by a bird," McCaul told CNN.
"Because we are a seaside course, birds have picked balls up in the air so we took it to be something like that, but then it became consistent and persistent.
"At first I took it as a bit of fun, as did most members, but it has got to the extent where it is having an effect on prizes and competitions and various other things."
One member, a former ladies' captain, had two balls taken by the pesky bird in the same round, costing her a prize in the ladies' match play competition.
"The second time it happened she was walking to the ball with her partners, and the bird came down 15 meters away, looked at them, picked the ball up and flew away," says McCaul.
"It's a very brazen bird, it doesn't know any fear. It sees a ball, takes it and away it goes and we have absolutely no idea why it's continuing to do it."
Ravens have a wingspan of some 4 ft (1.2m) and have a reputation for picking up shiny objects like pebbles and coins.
Some members think the bird is mistaking their balls for eggs. They claim to have beaten the thief by using yellow golf balls because the raven is only interested in snatching white ones.
At least six ravens are housed at the Tower of London at the British Government's expense because of the traditional belief that if they are absent the tower will crumble and the Kingdom of England will fall.
The birds are a protected species and officials at Greencastle have been warned off trying to catch their raven.
"I think it's here to stay," says McCaul. "Most people are just taking it as a bit of a hazard down here. You have bunkers and you have rough and now Greencastle have got the extra hazard of a bird."
Ravens are not the only animals to have made enemies of golfers.
Last year in Denver, Colorado-based TV station 9News carried a story of a man who had crafted a putting green in his garden only to wake up each morning to find a fox had stolen his golf balls.
Tom Houk eventually managed to catch the thief at work, but not before it had taken more than 100 of his balls.
At the Players Championship at Sawgrass in 1998, a seagull swooped down and snatched U.S. competitor Steve Lowery's ball off the green at the famous par-three island hole before dropping it into the water.
On the European Tour in December, players mingled with crocodiles at the Leopard Creek Golf Club in Mpumalanga, South Africa, for the Alfred Dunhill Championship.
At the only golf course on the island of Tonga there's a local rule which states that there's no penalty if a monkey steals your golf ball.
And in Uganda, golfers at the Jinga Golf Club are permitted a free drop if their ball lands in the footprints of a hippo.