A sheep has choked to death on a discarded bag of dog poo at a historic site near Norwich amid an ongoing battle with rule-breaking dog walkers.
A newly born lamb was found on Monday (May 22) lying next to his dead mother at Caistor Roman Town.
Growing reports of dogs being let off leads have prompted fears of a further tragedy if the situation continues.
Natalie Butler, director of Norfolk Archaeological Trust (NAT), which manages the site, said: "This event is an absolutely awful reminder of the consequences of people's irresponsible actions.
"It has been traumatic for the grazier who has lost one of his flock in such awful circumstances and impacted his livelihood.
"We ask people to please follow the rules as closing the site entirely is the last thing we want to do but if incidents like this continue, it is something we will have to consider."
Members of the public have reported incidents of sheep worrying to the NAT at least three times a week as more people visit the site in the warmer months.
Sheep worrying, which includes attacking or chasing sheep, causes the death of many animals each year and is a criminal offence.
It is the latest incident at the important archaeological site, which hundreds visit to see the remains of the largest Roman town in East Anglia, Venta Icenorum.
Workers and volunteers at the site have faced continued abuse from dogwalkers refusing to keep their animals on leads.
Since the start of this year, it has also been plagued by vandalism and thefts of high-value cameras.
Ms Butler added: "People need to take responsibility and put their dog poo in the bin.
"We have plenty on the site so there is no excuse."
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