Bristol Zoo accused of causing undue stress to animals with hen parties and stag dos

Undercover footage shows lions pacing up and down at zoo's Big Night Out event, but zoo deny they were in any discomfort

A zoo has been criticised by a campaign group for staging an adults-only "Big Night Out" event aimed at stag and hen dos amid claims it made animals "highly stressed".

The Independent has been passed undercover video footage of two lions pacing back and forth rapidly for several minutes during the Friday night party at Bristol Zoo, where there was alcohol and loud music from a live band.

Such behaviour is believed by many vets to be a classic sign of stress, but the zoo categorically dismissed this, saying the lions were taking an “interest” in the event and “the pacing seen in the footage was in anticipation of seeing [their zoo keepers] and not as a result of sound levels”.

The event, which charged £15 a head for 1,400 people, was billed by the zoo beforehand as “perfect for birthdays, stag and hen parties” and where “animal welfare would not be compromised”.

It ran until 10.30pm and featured bars, a live band, a “silent disco” at which some dancers sang loudly while wearing headphones, and gave access to the boundaries of secure animal enclosures where revellers were allowed to take pints of lager and cans of Jack Daniel's mixers.

Alcohol-fuelled events were scrapped by London Zoo last year after a series of revelations about the behaviour of revellers in 2014, including a man pouring beer over a tiger, another man stripping off and trying to jump into the penguin enclosure, and a drunken woman reportedly trying to enter the lions’ den.

At Bristol, the live band and dance floor were in the zoo’s grounds but away from the main animal enclosures.

Comments left on the zoo’s Facebook page in the days after the event suggested the noise could be heard by residents in the Bristol area two miles away.

A poster for Bristol Zoo's Big Night Out party event

The event took place on 29 July and was covertly filmed by an investigator from the Captive Animals’ Protection Society (CAPS), which campaigns to ban animals being kept in zoos. The investigator mingled with partygoers around the zoo’s grounds and with the exception of a couple of boisterous voices they were found to be generally well behaved and respectful when near the animals.

However, the investigator was alarmed by the relentless pacing up and down of the two large lions. When she asked a zoo staff member for an explanation, she was told: “Because there is so much going on that is unusual for them. Obviously normally there's not music, normally there's not people here at 10 o'clock at night, it does stress them out a bit... it can be a trigger to stress.”

Bristol Zoo said the staff member was not a qualified keeper, but declined to specify what experience she had or even what job she was carrying out.

A spokeswoman said: “Our two male lions were monitored throughout the evening by our qualified animal keepers.

“The lions were hand-reared by our keepers after being abandoned by their mother at 13 days old. As such, these keepers became their ‘mother figures' and they still have that association. The pacing seen in the footage was in anticipation of seeing someone they knew and not as a result of sound levels.

“They also had access to their quiet, off-show dens but chose to spend their time in the main paddock. We cordoned off this area to keep guests away from the glass to minimise any additional disturbance out of normal operating hours. They spent a large part of the remainder of the evening resting or sleeping.

“We strictly monitor noise levels throughout the event to ensure they do not exceed levels set by the local authority and that are comfortable for our animals and guests.

“Approximately 1,400 people attended the event. We had a strong staff and security presence on site to monitor guests, which meant we were able to allow food and drink into areas where it is usually prohibited.

“The Big Night Out, which has been held at the zoo over the last three years has been a huge success. Most importantly, our guests have consistently shown a huge amount of respect for the zoo and our animals, which makes us feel proud of Bristol, the people who like to enjoy the zoo and the events we put on.”

But Marc Bekoff, former professor of ecology and evolutionary biology at the University of Colorado in the US and a patron of CAPS, said: “These lions are clearly highly stressed. They are pacing back and forth and extremely vigilant. If they behaved like this every day I'd imagine they'd suffer from severe psychological problems from this level of stress.”

Nicola O'Brien, campaign director at CAPS, said: “This is not the first time we and others have documented the negative impacts of these night time events on animals yet zoos continue to run these events.

“The only way to prevent this happening again is to end them once and for all. If zoos really care about animal welfare, they will stop organising these events.”