The Irwins have been taking in and treating hundreds of displaced animals at their wildlife hospital as the fires rage on

As the Irwin family continues to do their part helping with the Australian wildfire crisis, they say they’ve been moved by many emotional moments. However, for Robert and Terri Irwin, some of the heartbreaking scenes have risen above the rest.

“I think for me, it’s watching the people on the front line,” Terri, 55, tells PEOPLE of her most emotional moments of the fires so far.

Terri said she was appreciative of all that the firefighters were doing amid the challenging chaos.

“We have firefighters here from all over the world — from the United States, from Canada — and as the animals come out of the forests seeking help, they just walk right up to the firefighters, and the firefighters are giving them water and they’re ending up with animals climbing up on them trying to seek refuge,” she says.

“It’s just heartbreaking watching these heroic firefighters also trying to save wildlife,” Terri adds. “It’s unbelievable… when these animals are terribly injured, they’re hit by cars, they’re burned, they’re trying to seek solace wherever they can — it really is heartbreaking to watch.”

Robert and Terri Irwin
Robert and Terri Irwin

Robert, 16, echoed his mother’s sentiments, opening up to PEOPLE about seeing “the devastation from all across the country.”

“It’s really quite overwhelming but when you get the individual animals in — like the koalas, like these little flying foxes — and you put a face to it, it really puts it into perspective, and it really makes it even more devastating because you realize that half a billion animals — that’s half a billion little lives just like these guys — [are in danger]. It’s just such a heartbreaking situation.”

The Irwin family has been taking in and treating hundreds of displaced animals at their wildlife hospital at the Australian Zoo as the fires rage on. (They recently treated their 90,000th patient at the hospital.)

Though they’re safe from the flames, Robert and Terri, who held fruit bats who were harmed in the fires during the interview, say they’ve been swamped helping as many affected animals as they can, in addition to their regular duties.

“The bushfires that we’re seeing at the moment are unlike anything in Australia’s history and they’re some of the biggest in the world,” Robert explains. “For us, with the devastation we’ve seen with wildlife and with habitat, we’re really just doing our best here… to take in as many species as possible.”

“And then unrelated to the fires, we just treated a giant sea turtle just yesterday,” he continues. “It’s everything on top of what we’re trying to treat from these fires, so it’s definitely busy times for us, but we’re trying our best to treat every individual that we can.”

Adds Terri: “It’s been very dramatic. Our average number intake has more than doubled and we’re getting an influx of huge numbers of animals.”

Since September, at least 25 people have been killed while a whopping 12 million acres have been wiped out with hundreds of homes and buildings destroyed, as well. A seven-day state of emergency was declared on Dec. 23.

As of Wednesday, experts said the fires burning across Australia have likely left more than one billion animals dead, according to Today.

Ecologists from the University of Sydney believe 800 million total mammals, birds and reptiles have died in the state of New South Wales since September, professor Chris Dickman told the outlet. That massive number includes a third of the New South Wales koala population, and fatalities are only expected to increase.

For those who want to help with the devastation from the fires, the Irwins say the best thing to do is donate money.

“Everyone has two things in our lives to varying degrees: you’ve got time and you’ve got money,” Terri says. “If you combine your $5 with everybody else’s $5, then you really start seeing this positive change.”

“There really are so many different organizations working hard to get the resources and the funds to the people that need it most,” Robert adds. “I think that everyone can definitely help with this seemingly insurmountable situation we have, but I think if we all come together and we all do our part, we can definitely make a positive change.”