It's a North American Zoo response , policy isn't correct word but guidance is closer , to severe weather owing to the potential of severe structural enclosure damage. North American thunder storms depending on area can be extremely violent, blowup extremely suddenly, as in close to tornado scale. I've seen it 1st hand many times.
Lock up of species is for security and also to prevent animal losses depending on facility location in the risk of a lightning strike on mega herbivores.
That has happened in North American Zoological collections.
Not as far as I know in UK .
Thunderstorm changing to potential of an actual or very near tornado is a fact for a large percentage of zoological facilities In North America- a real summer nightmare . Standard practice I've dealt with is prioritize mega herbivores, large carnivores and large primates- get them in secure holding inside.
If time and staffing allows , severe storm alerts can blow out of nowhere with not a lot of warning, get pretty much anything else in as well .
Protocol usually states clearly to not allow stock back out until the weather alert is passed, and office clears a stand down .
If it's in afternoon close to time when a facility that night houses species, then the animals will not go back out. They will have their end of day routine during the storm and that gives keepers a chance to check for damage after weather alert is stood down and get repairs done in morning. We're not talking about just hot wire going off from potential electric outages or few ree limbs off- but actual fences coming down, severe flooding compromising moats , roofs disappearing , woodland trashed.
Some locations in north america at some points of year this could be happening several times a week for short periods .
North American Thunderstorms wind and hail damage , hail can be golf ball to apple sized ! in a zoological facility has to be seen to be believed.
If the facility is in an area than can experience these weather conditions the main office , security and usually guest services has the doppler alerts on at all times in season and will immediately notify head management, who then instigate lock up , even if facility is just outside the area as a precaution in most cases.
The real nightmare if there is a POTENTIAL , then response is instigated and it's still a blue sky summer day .if the storm direction changes but the facility is still in the at risk zone the stock stays locked up until alert is past . Then it appears it was done for no good reason. But animal, staff and visitors safety comes 1st.
It's a huge pain in the arse for animal management , and yes joe public are not always understanding, read are usually vocally angry but depending on location it's a very real , needed and vital security measure that will happen multiple times in a season.
Hope that explains Mr Bobcat why ur zoo afternoon got ruined . The facility was being responsible and accountable to its stock, staff, visitors and surrounding community. But they failed to explain WHY it happened and imo that's not fair on visitors.