This heartbreaking image shows an entire family of regal swans which were killed after becoming trapped in a concrete weir.
The bodies were discovered in the small enclosure on the river Syling, near Dorchester, Dorset, 200 yards from their usual swim and nesting area.
The Environment Agency is investigating the tragedy, but it is thought the birds were frightened downstream by other works going on upstream.
Marine wildlife photographer Steve Trewhella, who retrieved the bodies. said: “Once they fall into it they don’t stand a chance – it’s a death trap. I think they either starved or drowned. It’s a sad end to an entire family.
“I don’t see why it has to be boarded up in the middle of July. If the wooden boards weren’t in place they might have been able to get out.
“I understand that these things are needed to help with water flow but they need to be safe for animals.
“I wouldn’t be surprised if there were other bones at the bottom of that weir. No animal would escape it. It’ll happen again as well.”
Residents believe the swans were led towards the weir after being disrupted from their home by other planned works.
The Environment Agency confirmed while the weir was not one of its structures, it would visit the site to asses how safe the structure is.
A spokesman said: “We think the structures are owned by Dorset highways or network rail but we can’t say which for sure.
“We have no operational responsibility but we’ll get an expert to look at it and feed back to Dorset Wildlife and the responsible party what we think.
“If it’s inherently unsafe for wildlife we will contact whoever is responsible.”
The Environment Agency’s Good Practice guide to River Weirs states: “Weirs create a barrier across the river that can adversely affect wildlife (especially fish) and recreation.
“Appropriate design can ensure that the adverse impacts are minimised or eliminated, or even turned into a benefit.”