An ear in the forest

Pete Knock, Nature Conservation Council
Ecologist Pete Knock installing nest boxes, Bungawalbin. Photo: Jimmy Malecki
Ecologist Pete Knock installing nest boxes, Bungawalbin. Photo: Jimmy Malecki

When you work as an ecologist, you walk into a space, and you’re trying to read everything in the landscape. You’re trying to pull out all the information you can. It’s a narrative. For me, it’s always around what’s happened at a site previously. If there’s a historical event, a fire event, a natural disturbance, that sort of thing. You can start to read it like a book. 

That’s the sort of work we’re doing here. As an ecologist with the Nature Conservation Council I’m employed specifically to work on the large forest owls program. Our main focus was the barking owl but we’re looking at all large forest owls the powerful owl, masked owl and barking owl.

There are two main strongholds of barking owls in the state: the Pilliga in the northwest, and then the north coast, the lower Richmond. We’ve got acoustic monitors in the forest, trying to pick up and detect owl calls. We’ve been monitoring these sites for almost three years. 

Starting in the winter of 2019, and all the way through into summer, multiple fires ran through the study area. 

We had 26 properties we were working on before the fires, and only two weren’t impacted

Songmeters installed at monitoring sites melted in the fires. Photo: Pete Knock

We lost acoustic monitors, burnt and fried in the fires. Most of our sites were burnt at various intensities. This fire in particular was huge. It started up at Myall Creek Road and burnt in a southerly direction in a big anchor shape. One arm of it went west, across the Summerland Way out into the Banyabba sandstone country. Another arm went east, crossed the highway, burnt out towards Iluka, then burned north under a southerly wind, all the way up to Gap Road, nearly to the Evans River.

I couldn’t get up here to rescue sites. I was fighting fires on my own property, a place I had lived for 20 years. Every one of my rainforest trees burnt out in that fire event. We fought through the night and protected a lot of our houses. At the same time I knew full well I had study areas with landowners who were also fighting fires on their property. 

After the fires we changed focus. Instead of just monitoring owl calls, we added more species to the mix. We really wanted to pick up what was actually happening in the forest. We started to monitor all the other arboreal mammals: squirrel glider, yellow-belly glider, common brushtail, sugar glider and koala.

Our pre-fire data gives us a bit of a baseline to know which species were at different sites. Even though it was extremely dry drought conditions, some of our sites had the full complement of species. One site in particular stands out. I had all three owl species there. I had koala and squirrel glider calling at those sites, and common species such as the brushtail possum. The early fire in spring which was the Busbys Flat/Rappville fire was an extremely hot, fast fire.

Post-fire, the only thing I got immediately was the cane toad moving through. 

I got predators, cats and foxes, but none of those arboreal species. Nearly two years post-fire I haven’t picked up barking owl calling there. Their habitat is smashed. That site had a lot of logging around it in the previous 12 months. A lot of fuel on the ground. That was one of the few sites where post-fire I actually saw animals dead on the ground: wallabies and echidnas that didn’t escape the fire. That gives an indication of how hot and how fast that fire moved through. 

Some sites are recovering better than others. That’s a result of fire intensity generally. Many large trees that already had fire scars succumbed to the fire. The fire gets into the core of them and burns up and out through the hollow stems, and eventually the whole tree will burn out and collapse. That was a main impact. A lot of the hollow-bearing trees that were damaged are still falling over.

Powerful owl (Ninox strenua) snacking on a brushtail possum in the Bungawalbins. Photo: Pete Knock

Just before the fires we were monitoring two nest trees, one on Kewilpa another conservation block and one over on Minyumai, which is an Indigenous Protected Area. Both trees were impacted. The tree at Minyumai was damaged and it looked like the owls abandoned the nest and the owlets probably perished in the tree before they were fledged. The one on Kewilpa we’d only found three or four weeks before the fires. That tree was burned through and we lost the owlets in the tree. 

That really got me, the loss of that tree, the physical loss of the owlets. 

Most of these species were already on the threatened species list. Once you’ve lost those big trees, it will take another one- to two-hundred years to even get anywhere near close to producing hollows, let alone a hollow that an owl may favour. Especially the powerful owl, which is the largest forest owl. They need a hollow 30 centimetres in diameter, and a pipe that might be one to two metres deep. That just physically takes time to produce. 

We’ve got the hard data to say this fire was a mega event a catastrophic event

In areas there’s been multiple years of no breeding. Not only have the owls lost some of their trees, and they lost owlets, not being able to breed for two or three seasons post a large fire event has major implications. For an owl, when it’s breeding, it’s about trying to provide enough food resources to those young for potentially six to nine months. Having forests that are fully complemented with hollows, so that you’ve got a huge prey base, a feeding resource for the owls, needs to happen before the owls are capable of having enough energy to provide for their young. 

Originally, we weren’t concerned with nest boxes because we were just monitoring birds, trying to create a narrative with landholders, trying to have a concept in their management plans of protection over time. Then the fires ran through the project. We didn’t have funding for nest boxes, so we put up a crowdfunding campaign. I’ve worked in a lot of government departments, and I was quite sceptical. But within weeks, we had enough to go purchase nest boxes. It was a revelation, we can actually change things very quickly under that model. 

So I ordered the boxes from Hollow Log Homes, and Alan rang me and said, ‘Have you just heard? Queensland’s closing the border.’ We had to react. I can climb, I can install nest boxes. I drove with a truck and trailer, got 150 boxes on board within a day of the border closing, just to get these boxes into the air.

Just last week we finally got confirmation for the BOBCAT program – Barking Owls of the Bungawalbin Catchment. We’ll be continuing our work, working on eight key properties in the Bungawalbin area, and we’ll be continuing the nest box program. We’ll use the song meters to monitor all the acoustic work on the owls and all the other species that we can pick up. And we’re going to be mapping old growth, trying to get a handle on basically that last big resource, the big hollow-bearing trees.

Fire and smoke pours out the spouts of a large hollow-bearing eucalypt in the Bungawalbins. Photo: Jimmy Malecki