Hedge cutting on wildlife-rich marsh land on Anglesey has been described as 'vandalism' by naturalists.
The coppicing, between Malltraeth and Llangefni, has been carried out by the Environment Agency Wales as part of flood prevention work.
An Agency spokesman said it was essential work, and the hedge would be ready for next year's nesting season.
Naturalists say the work has been carried out incorrectly and birds wintering in the area will suffer.
"I was very depressed when I saw what they had done, as I thought the agency was meant to defend the environment," said keen naturalist and walker Tudor Williams.
"It's just they have done such an awfully bad job, it beggars belief to see such vandalism," he added.
'Attack on wildlife'
Mr Williams said the marshland was important for birds such as the Field Fair and Redwing, which come to the area to overwinter.
"They eat the numerous berries that are left on these types of hedges," he said.
"I see the cutting of these hedges an unreasonable attack on wildlife," he added.
Elwyn Thomas, who has a background in agricultural engineering, said cutting the hedges as the Agency had done was "not an unusual practice".
"Unfortunately it's not the correct piece of equipment to use and there are items on the market which can do a much neater job," he said.
"I think they've missed a golden opportunity too, as in that hedge there must have been sycamore, larches and all sort of other varieties, and we are so short of mature trees on Anglesey."
He said the agency had gone along with a "machine capable of mutilating the hedge", and there was an "obsession with tidiness".
"In some areas you see long boxes with no tree growing in the middle of them at all... eventually there will be no hope of seeing mature trees anymore, and I think that's a retrograde step," he added.
Mike Davies from the Environment Agency said that the hedges had to be cut because they grow on cobs which have been built to stop flooding from the Afon Cefni river and the sea.
"They form and important part of the environment and in terms of habitat they are very important," he said.
"But if allowed to grow too tall they become straggly and can be susceptible to wind damage, which can cause the roots to undermine the embankment," he added.
Mr Davies said the "priority" was to get a healthy hedgerow.
"We're not destroying the hedgerow and we're encouraging a strong growth, but at a lower level," he added.
"It will be there as important habitat for nesting birds in the spring, and we're also leaving the more mature of the trees as these have a crop of berries which will provide food for small birds during the winter."