New safety measures have been added to overhead power lines near a nature reserve after reports of swans being killed by them.
Posting on social media, ornithologist Josh Jones said a number of swans had been killed by power lines on Baston Fen, Lincolnshire.
He said the wires were close to feeding grounds used by the mute swans.
Western Power Distribution said it had fitted diverters to make the lines stand out to birds in flight.
Mr Jones, who works for Birdguides magazine, said he spotted four dead swans along a short stretch of road while out bird watching at the weekend.
"They were in various states of decay, some looked fairly fresh, and some looked like they had been there a couple of weeks," he said.
"It was quite a disturbing find."