Edinburgh Zoo is preparing to open at the end of June after owners warned being closed over the summer would be “financially disastrous”.
The Royal Zoological Society of Scotland (RZSS) said the same applied to Highland Wildlife Park in Kingussie.
The wildlife conservation charity confirmed it has had to borrow £5 million in the wake of the Covid-19 pandemic.
It said basic running costs to keep the facilities going amounted to almost £700,000 per month.
Both attractions are in the process of putting in place safety measures to protect visitors and staff.
These include closing indoor areas, limiting numbers and selling tickets online with time slots.
RZSS chief executive David Field, who started in post this week having moved to Edinburgh from East Anglia, revealed the pandemic had already caused heavy financial losses.
“Almost all our income comes from our visitors and around 65% from April to August,” he said.
“We have furloughed staff and our generous supporters have raised funds to help feed our animals but we have still had to borrow £5 million.”
Mr Field said the UK Government has stepped in to help smaller zoos protect animal welfare through the zoo emergency fund but unfortunately RZSS and other large, charitable zoos are not eligible to apply for this support.
He said repaying their multi-million-pound loans will have a significant impact on their parks and their globally important conservation activities.
“If we cannot reopen soon then we will need to borrow even more, which could be financially disastrous,” he added.
“When this crisis is over, connecting with nature and being close to animals is going to be more important than ever, which is why it is vital that our parks open again.”
