WILD Zoological Park, at Halfpenny Green, is to remain closed for another month and without donations director Zachary Hollinshead said it would have "gone under" months ago.
He said between £12,000 and £15,000 was needed just to cover the month of closure.
Mr Hollinshead said: "With another month of unexpected closure and most of our April revenue refunded, we are clinging on for dear life.
"We are devastated that we cannot open alongside our friends and colleagues in other zoos around the country.
"We have had to refund a lot of people which has plunged us deep into our overdraft and we simply can’t afford to do it.
"The reason we are unable to open is that we are not really like a normal zoo as WILD is a highly interactive experience and when people come they expect to see our famous displays and shows and inter-activity, none of which we are permitted to do with the current regulations in place.
"We can easily safely control an outdoor socially-distanced bird display, much safer than the manor in which people are interacting in public at the moment.
"However, the latest government documents clearly state that zoos should not be operating demonstrations even if they are outside with social distance and control measures in place.
"We’re also still not able to open our indoor, undercover or semi-indoor areas such as our reptile house, even though it is in exactly the same building and occupies the same space as our reception desk and gift shop which are permitted to open.
"Nor are we able to open our Amazon walk-through experience which is home to free roaming monkeys, parrots, jungle cats, honey bears, iguanas, tortoises and armadillos.
"We are home to the UK’s biggest free-flying bird show, where visitors encounter flocks of free-flying parrots as they zoom over the vines at Halfpenny Green wine estate.
"Travelling fun fairs are able to open, beer gardens, theme parks, grassroots sports are allowed spectators but we can’t do a bird display.
"The park has a lot to offer but it’s on a small footprint, with the current restrictions fully adhered too, we just could not operate with enough people to make it financially viable, and without the go-ahead to operate properly, we’re forced to stay closed."
The park is now selling open-ended tickets valid for a whole year and has Gofundme and PayPal support pages.