Zoo director Derek Grove said even when the well-known Castle Hill attraction opens it will have to limit visitors to a fifth of what it could hold at peak times.
Over the Bank Holiday the zoo and castle could expect 5,000 people through its famous gates especially with the Black Country basking in warm and sunny weather.
But Mr Groves said staff would have to restrict visitors to 1,000 when it reopens, as staff keeping their fingers crossed that will come by the middle of the summer.
Losses have impacted on the zoo's plans for a new orang-utan enclosure amid a £2.2m scheme to bring other improvements to 40-acre site.
The attraction has been unable to furlough all its staff due to animals needed daily care - in contrast to many other closed tourist destinations.
Zoo reveals mounting coronavirus costs
The sky is blue, the sun is shining, the flamingoes are basking in unseasonably good weather. The peacock has also decided to stretch his legs, after a fall-out with the pheasants. This is the type of day Dudley Zoo was made for.
"On a bank holiday, with weather like this, we should be getting about 5,000 people through the gates," says zoo director Derek Grove.
But the 40-acre zoo is eerily empty, save for the odd keeper you see around tending to the animals. Like other tourist attractions across the country, the zoo has been forced to close as part of the Covid-19 lockdown, with no official word from the Government about when it can reopen.
"We're looking to reopen on July 4, but nothing has been confirmed so far," says Mr Grove.
The lockdown has proved expensive for the zoo. Unlike other tourist attractions, it can't shut down and furlough all its staff. At the moment there are about 40 staff working on the site, compared to the usual 80 full-time and 50 part-time workers.
"At the moment we're losing about £50,000 a week," says Mr Grove.
"It was £300,000 a month, but we've managed to get it down from that."
But even more costly is the fact that the attraction has lost the income from its peak season – April and May are traditionally the busiest months of the year – that would normally see it through the loss-making periods of autumn and winter.
The losses have also eaten into reserves which had been set aside to fund £2.2 million worth of improvements to the site over the next couple of years.
Work had been due to begin this winter on an £800,000 new orang-utan enclosure, but that is likely to be postponed.
"We will carry on and do it, but it's impossible to say when until we know when we reopen," says Mr Grove.
Plans to extend the giraffe and tiger enclosures are also likely to be delayed, while the setback could also throw doubt on plans to reintroduce brown bears for the first time in 40 years.
The latter is particularly problematic for the zoo, as it has already committed to taking in a pair of orphaned rescue bears from Slovakia.
"We were hoping to have them in for the summer," says Mr Groves. The animals are due to inhabit the bear ravine, which was restored in 2015 as part of a £1.15 million lottery-backed scheme.
However, to bring the enclosure up to modern standards, it will be necessary to build a new house for the animals, and there are fears that the shut-down will delay the work. Again, Mr Grove is unable to say what will happen, as it depends on when the zoo will be allowed to reopen.
Even when the zoo does reopen, it will be very different to the usual scenes during the summer.
"To begin with, we will limit it to 1,000 visitors, all with tickets they have purchased in advance," he says.
"We will start off with 1,000, to see what it looks like, we have got a lot of roads and paths, so we will see if people keep at a safe distance."
Indoor attractions, such as the reptile house, will be closed to begin with, and hand-sanitiser dispensers have already been installed at various points along the site.
Mr Grove says it has also been a difficult time for the animals, who are missing the company of visitors.
"You notice when you walk past, that they are more excitable than usual," he says.
"People say they don't want humans around them, but that's nonsense. Most of these animals were born in captivity, and so were their parents, they have grown up used to have people around them, and they miss them when they are not there."
For Mr Grove the frustrating thing is the timing of the pandemic, both in terms of the season, and also the way it is frustrating the progress of the zoo at a time when the future is looking brighter than it has done for a long time.
"You don't normally get the bank holiday and the good weather coming together, we have been waiting for this for years, and when it finally comes along this happens," he says.
Last year, the zoo saw a 311,303 visitors pass through its turnstiles, its best figure for 30 years, and over he past few years visitors have consistently passed the 300,000 mark.
"Twelve years ago, we were getting 160,000 visitors, and we couldn't survive without the local authority's help," he says.
"Now we are making a surplus, and all of that is ploughed back into improving the site, which in turn brings in more visitors.
"It's actually depressing. We are now on the crest of a wave, we are so close to doing some of the things we have been looking forward to, we have got this close.
"Given the size of the site and the location, we should be getting 400,000 to 500,000 visitors in, although the constraints of the site mean that 500,000 would probably be about our limit."
But while Mr Grove is clearly desperate to get the zoo open to the public as soon as possible, he also acknowledges that such frustrations pale into insignificance compared to the impact the virus has had on others.
"We have to put it in context," he says.
"Nobody at the zoo as died from coronavirus, or lost anybody to it, and that is what is more important."