A pod of killer whales has been spotted in the Firth of Forth, killing and eating seals.
Rab Harrower saw one of the orcas while out on a boat in the Forth
The orcas have been seen near the Forth Bridge and close to Hound Point.
Wildlife experts believe the mammals have been enticed to the area by seal pups but are surprised they have come so far inland and so far south.
Rab Harrower, who was working on the Forth Rail Bridge and saw one of the orcas, said: "We have seen minke whales and dolphins but never killer whales."
Mr Harrower, a safety inspector, has been working on the bridge for more than nine years.
Along with his colleagues he had seen one of the mammals several times from the bridge, then came across it while out on a boat taking photographs of the bridge.
"I was about 40 metres away from it," he told the BBC News website.
"It was about 12ft to 15ft long and looked like quite a young whale.
"I saw the blowhole first. The whale popped up about three times then disappeared then came up in another area.
"You could see it was a killer whale as when it dived you could see its white underside and white neck."
Some of the workmen said they had seen a few orcas but there have been reports of up to nine.
The workmen also said they had seen the mammals killing and eating seals.
The orcas are thought to have been drawn to the Forth by seal pups
Colin Aston, who runs Seafari Adventures wildlife trips in the Forth, said he had not come across killer whales in that area in 30 years.
Mr Aston, who also runs the Maid of the Forth, said: "They will be there for the seals as there are a lot of grey seal pups around at the moment which are just learning to swim.
"I've heard of killer whales coming as far as Isle of May at the entrance to the Forth but not as far as the bridges."
Pc Mark Maylin, a Fife Constabulary wildlife officer, understands the orcas have been in the area for about a fortnight.
"The man I spoke to was out in his boat and came within five metres of one," he said.
"He said there was no question it was a killer whale.
"They normally hang around in pods so if this is a pod it is certainly very unusual."
There have been reports of up to nine whales being spotted
Pc Maylin warned whale watchers to avoid getting too close to the orcas but said they should be visible from the shore.
"There is a lot of shipping in that area so we will just have to hope the whales can keep out of the way," he added.
Natalie Smart, spokeswoman for the Scottish SPCA, said: "These creatures are usually seen up north around Orkney and Shetland. They are also usually spotted in the summer months.
"It is very unusual for them to be spotted this far south in January which could be due to the warm winter.
"We just hope that after feeding they'll move back out to sea."