Security guards at Hampstead Heath have been threatened by individuals trespassing in protected bird ponds during a recent heatwave, prompting authorities to install barbed wire fencing. The measures come as temperatures soared, with the UK experiencing its hottest June day on record.

Ponds historically preserved for wildlife habitats, including nesting ducks and swans, have been invaded by swimmers seeking to cool down. These individuals are reportedly bypassing the designated, bookable swimming ponds located nearby, choosing instead to enter restricted areas.

Two security guards, hired by the council to manage crowds, stated that despite their presence and the posting of "NO SWIMMING" signs, rule-breakers continue to enter the water. The guards, who spoke anonymously, described confrontations with trespassers, some of whom have allegedly issued threats. "They often get aggressive and try to fight us," one guard told the Daily Mail. "They actually come up to us and say 'we see you every day, we're watching you, trying to intimidate us.'"

The guards also indicated they lack the authority to issue fines or penalties, being limited to questioning individuals and asking them to leave. They report issues to a superior officer but stated that more personnel would be needed to effectively manage the situation. "We can't give out fines, we can just report it to our officer at the Hampstead Heath constabulary but the authorities know about it. But we need four or five officers to actually tackle it," one guard explained.

In an effort to deter further intrusions, barbed wire has been erected around the perimeter of one of the ponds. This escalation follows similar incidents during a May heatwave, where swimmers were observed entering the protected habitat while ducklings and cygnets were present. A video obtained by the Mail showed approximately 20 people swimming in the model boating pond on a day when temperatures reached 35C.

According to the guards, the trespassing is not limited to a specific age group or gender, with all demographics reportedly participating. They described a pattern where one individual enters the water, is applauded by others, and subsequently, numerous groups follow suit. The guards estimate that approximately 90 percent of those present will break the rules, despite the presence of a smaller group who adhere to regulations.

Some individuals, however, expressed frustration with the booking system for the official swimming ponds, deeming it overly bureaucratic. One young couple argued that public spaces should be freely accessible on a first-come, first-served basis, rather than requiring advance booking. They also voiced dissatisfaction with the allocation of gendered swimming spaces. Another resident, David Paul, a retired artist and fisherman, voiced concerns about the environmental impact, citing instances of nests being destroyed and the disturbance of sediment at the bottom of the ponds, which he believes can be harmful to wildlife and fish.

"When they stir up the bottom it's been undisturbed for a long time there's stuff at the bottom that should not be coming to the top. Like blooms and things," Paul stated. "But last year, there was a nest destroyed which was sunk by swimmers who shoved it to the bottom."