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From Schwartz Media, I’m Osman Faruqi. This is 7am.

After suffering through record-breaking bushfires, a pandemic, and floods, big parts of Australia now have a new problem: a plague of mice.

Farming communities across New South Wales and Queensland have been overwhelmed by one of the worst mouse infestations in recent history, threatening crops and livelihoods.

Today, the CSIRO’s Steve Henry on the origins of the mouse plague, the impact it’s having, and when it might finally end.

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OSMAN:

G’day, Steve, you there?

STEVE:

Yeah, g’day Os, how are you going?

OSMAN:

Good, good, how are you doing?

STEVE:

Yeah, yeah, flat out, but good.

OSMAN:

You're currently travelling at the moment.

STEVE:

Yeah, we're in Canamboole so I've just done talk two of seven over there this week.

OSMAN:

And what are you talking about, you talking about mice?

STEVE:

Basically about mice and protecting the sowing of the winter crop.

OSMAN:

Have you seen many mice on your trip so far?

STEVE:

A few - so we were just driving back from where we had dinner last night back to the motel. There was - on a road down the outskirts of the town - we saw about 20 or 30 mice running across that road. So it means that there are still quite a few here, though they've certainly quietened down a bit after the rain, but there's still lots around.

OSMAN:

So Steve, to understand what we’re seeing right now…what do you think we need to know about mice?

STEVE:

So, wherever there are humans in the world, there are mice; and there are even mice in Antarctica as well. So they are really well adapted species to living in a wide range of habitats.

And the reason they're able to do that is because they're basically breeding machines. They start breeding when they're six weeks old, and they can have a litter of 6 to 10 pups every 19 to 21 days. But the kicker in all of that is that there's no break between production of pups. So as soon as they give birth to one litter, they can fall pregnant with the next litter, so there's no break in the production of offspring.

So mice are present all the time, even in really bad seasons. But they're there in really low numbers, essentially almost indetectable, or undetectable. And then when conditions become favourable, all of these small little populations that are there hanging on, start breeding. Then those populations get bigger and bigger and bigger, and then they all join up. And we get to the situation that we've been in over the last, probably 6 to 8 months now; so we started to get reports of higher than normal numbers of mice last September.

But what happens as we get these really favourable conditions, we get a really high level of survival of the juveniles. And when that happens, you get a lot of animals going on to breed. And because conditions have been really favourable for growing crops, we've got lots of food in the system, lots of shelter, good moisture through the summertime; and so they started breeding early in the spring, and then they've just continued to breed through the spring into the summer, and now they're continuing to breed through the autumn.

OSMAN:

Steve, in these really infested communities that are overflowing with mice, just how many mice are we talking about? What is it like in those communities right now?

STEVE:

So I guess in those scenarios that we're seeing on social media with vast numbers of mice all scurrying across the floor of sheds and banging into each other, there are literally millions of mice in these areas.

Archival Tape -- Unidentified Commentator #1:

“Check this out, welcome to Australia, home of the great mouse plague.”

STEVE:

And in some of the footage on social media, we're seeing mice flooding out of a grain storage area.

Archival Tape -- Unidentified Commentator #1:

“Look at that, look at all of that…”

STEVE:

And they'd actually almost made a little funnel that the mice were all running down and flooding like a stream of water into a 44 gallon drum.

Archival Tape -- Unidentified Commentator #2:

“Ohhh damn!”

STEVE:

Literally thousands of mice per hectare.

Archival Tape -- Unidentified Commentator #3:

“No! Oh my god.”

STEVE:

I know people that live in the big cities are horrified if they've got one or two mice in their houses.

Archival Tape -- Unidentified Commentator #4:

“Out of room 15 and 14 - the girls chased out of 97 mice out of two rooms.”

STEVE:

We're getting examples and anecdotes from people that live in rural communities of them taking, you know, 40, 50, 60 mice out of their houses from traps every night.

Archival Tape -- Unidentified Commentator #4:

“The wife’s been bitten, I’m pretty sure the eldest daughter’s been bitten by them.”

STEVE:

The situation is getting so dire in some locations, the local councils are having to find special places to get rid of the bodies of mice because they're starting to make the garbage bins stink.

So it's pretty nasty stuff.

OSMAN:

What you're describing, Steve, sounds kind of like a scene from a horror movie. It sounds so graphic and terrifying.

STEVE:

Yeah. And again, while people in the country are used to these kinds of things, it is really quite wearing. It's this constant presence of mice that actually starts to have quite a psychological impact on the way people go about their daily lives.

And one of the things that I found in the 10 or so years that I've been working on mice is that when I talk to people, no one forgets living through a mouse plague.

OSMAN:

We’ll be back in a moment.

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OSMAN:

So, Steve, we've got this huge escalation in mouse numbers. We've got them, you know, eating their way through grain stores in farms, and overflowing from farms into towns. What kind of impact is that mouse infestation, plague outbreak actually having on those communities?

STEVE:

So there's the economic cost of losing crops and losing hay sheds and damage to grain storages.

And so the reason for the talks that I've been giving over the last couple of days and for the rest of the week is around giving farmers some advice about different ways that they might be able to be prepared, to minimise the impact that mice have.

One of the things that they are really focused on is: how can we be prepared to deal with mice when we sow the winter crop? And the winter crop gets sown then in April and May.

But the other really unquantified impact of mice is the social impact. People living in these rural communities become almost psychologically impacted by having to deal with mice all the time.

Archival Tape -- Unidentified Commentator #1:

“We went from no mice, to seeing a couple of mice in our garage at night, turned the light on, to seeing 50 to 100 running around in the space of probably four days. It went from nothing to ballistic.”

STEVE:

Every day when you get up, there are signs of mice that have been in the kitchen while you've been sleeping.

Archival Tape -- Unidentified Commentator #1:

My pantry is like a ‘no go zone’. They get into the lounge room, they get in every cupboard. I've got a dead one now in my car so that when you turn the air conditioning on all you smell is dead mouse, which is really pleasant to drive anywhere.”

STEVE:

You go to your linen press to get fresh linen out of the cupboard and you can't use it because it's all been soiled by mice. You go to your pantry to get your breakfast and you can see where the mice have been trying to get into the plastic containers that you've put all your food in, because if you don't put it in plastic containers, the mice eat it all.

Basically, every time you turn around, there's a mouse. They’ve been running across your bed in the night. There's all of these sorts of things that actually start to wear you out. And then if you're putting bait around your house to control the mice, then they go under the house and die and the smell of the dead mice starts to filter up into the house.

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“We are seriously over it now, the place stinks!”

OSMAN:

And last week, Steve, you know, enormous parts of the state of New South Wales, including some of the same areas that were impacted by the mouse plague were experiencing heavy rain and floods. Did that have any kind of impact on the mouse situation?

STEVE:

Yeah, well, that was one of the reasons why I was enthusiastic to get up here into the heart of the country where the mice have been so bad. Because I wanted to see if, as we had heard, that a rainfall event would have a significant impact on the mice. Now, after talking to farmers at a couple of presentations, we think that it certainly slowed the mice down a little bit; and because burrows and so forth have been flooded by this rainfall event, that means that any of the young, highly dependent animals that were in the burrows will have been drowned by the rain.

But the adults have been able to escape this rainfall event and get away from the worst of the water. And they are still out and about, causing the damage that they were beforehand. So certainly from the farmers and people from the rural communities are saying we're seeing less mice, but there are still plenty around.

OSMAN:

Wow. So if, you know, once in a generation floods can’t end the mouse infestation, how does it come to an end, Steve?

STEVE:

So what typically happens at the end of a mouse outbreak is that the mouse numbers crash away very dramatically.

And this is a bit where the horror story continues because what happens at the end of an outbreak is because the mice are there in such high numbers, they are interacting with each other all the time. They're starting to run out of food and that's sort of making them stressed. And so they become more susceptible to disease because of that high level of interaction and that level of stress.

And because they're running out of food, they start turning on each other and eating the sick and weak ones, and they start eating the babies of other mice. And that basically stops the rate of increase, disease moving through the population, and that makes the population crash away very dramatically.

And typically, farmers tell us that basically the mice almost disappear overnight or over the course of a week or so. They go from really, really high numbers to really low numbers. And in 2017 when there were really high numbers in the southern cropping zone, I was getting phone calls from farmers saying, ‘well, wait a minute, where have all my mice gone?’

They just disappeared that rapidly.

So we're hoping that we're not too far away from that scenario in northern New South Wales at the moment. But it's almost impossible to predict because there are so many variables that lead to that happening.

It's a problem that isn’t going away anytime soon. And so being able to predict mouse outbreaks, provide farmers with some warning about what might be coming, and then provide them with some strategies that might enable them to be quite strategic about the way they control mice, might all lead to reducing impact they have through time because they're a problem that's just not going away.

OSMAN:

Steve, thank you so much for your time today.

STEVE:

It's been an absolute pleasure.

OSMAN:

It's been a bit horrifying for me, actually.

STEVE:

I'm pretty sure you'll sleep. It'll be okay.

OSMAN:

Steve Henry is a researcher at the CSIRO. He first spoke to The Saturday Paper about the mouse plague - and you can read that piece at ‘thesaturdaypaper.com.au’.

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OSMAN:

Also in the news today…

New South Wales’ Health Minister, Brad Hazzard has accused the federal government of undermining the state's vaccine rollout. Hazzard said he was ‘extremely angry’ at suggestions made by the federal government that New South Wales had been slow in distributing the vaccine.

He also said he had raised the issue directly with federal health minister Greg Hunt.

And fresh COVID-19 restrictions have been announced on the New South Wales north coast following a case of community transmission in Byron Bay.

People are being advised not to travel outside the four shires of Byron, Ballina, Tweed and Lismore, and those planning to travel there for the long weekend should reconsider their plans.

From tomorrow on 7am we’ll be re-releasing our three part series ‘Climate Change Will Kill You’, with journalist Paddy Manning. The series investigates the deadly impact of climate change, right here in Australia.

We’ll be back with new episodes from next Tuesday.

I’m Osman Faruqi. This is 7am. See you then.

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