Extreme heatwave temperatures over summer have led to a mass bird kill at Gluepot Reserve in South Australia's Riverland.

Key points: Record-breaking temperatures in SA's Riverland are thought to have killed many birds

Record-breaking temperatures in SA's Riverland are thought to have killed many birds More than 190 species of bird have been recorded at Gluepot Reserve in the past, including 18 threatened species

More than 190 species of bird have been recorded at Gluepot Reserve in the past, including 18 threatened species Portland couple Ted and Carmel Meissner spend a couple of months a year maintaining the natural environment

Ian Falkenberg from the reserve's management committee said more than 100 birds died in late December heat, and it was likely to have happened in other places across the state.

"Birds were basically dropping out of trees, they were found dead and highly stressed," he said.

"Irrespective of where those birds are, it's a really challenging time for them to survive."

Wood swallows, crows and wattle birds were among those that died, which Mr Falkenberg said was unexpected because they were generally more tolerant of the heat than other species.

The heat is still on

Now, more than two months since record breaking temperatures were recorded in the Riverland, the volunteer-run reserve is feeling the effects of ongoing dry conditions.

These birds died during an extreme heatwave at Gluepot Reserve in South Australia's Riverland in December 2019. ( Supplied: Ian Falkenberg )

"Just a look at the vegetation tells you the story," Mr Falkenberg said.

"There's a fair bit of die back of some of the smaller shrubs.

Mr Falkenberg said bird diversity was also low as dry conditions continued.

"Whilst we still have birds here, the species diversity is much reduced compared to what it was maybe a couple of years ago, when we had wetter seasons," he said.

"Some species may have migrated further south and to other less heat affected areas.

"The silence and lack of birds [when monitoring] the reserve is obvious."

More than 190 species of bird have been recorded at Gluepot in the past, including 18 threatened species, and Mr Falkenberg hopes to see a return of these numbers into the future.

"This is why it's so important to monitor bird numbers each season to gain perspective of the changes in the numbers and varieties of birds that rely on Gluepot's Mallee habitats," he said.

Volunteer rangers 'backbone' of Gluepot

The Birdlife Australia-owned property spans 54,000 hectares and is maintained solely by volunteers, including the rangers who live at Gluepot for several months at a time.

Ted and Carmel Meissner have volunteered as rangers at Gluepot Reserve for about a decade. ( ABC Riverland: Anita Ward )

Portland couple Ted and Carmel Meissner have spent a couple of months every year for the past decade maintaining the natural environment.

"We like it, and I like the desert, which is interesting because prior to that, my wife and I lived on a yacht for 27 years," Mr Meissner said.

"So we went from one extreme to the other virtually. And we enjoy it — we enjoy the work and everything else."

Mrs Meissner said each working day at Gluepot was busy, but always rewarding, and by the end of the stint, they did not want to leave.

"A regular day always starts with a coffee to get you going," she said.

"Then we're out doing the weather reading for the bureau for 9 o'clock, before we go out in the truck to check the electric fence."

Dry times taking toll on environment

The volunteer ranger says the dry conditions are taking a toll on the environment, which boasts some of the oldest Mallee scrub in the region and provides vital homes for wildlife, in hollows and shrubs.

"We've noticed the trees and bushes are losing their leaves and needles and don't look alive," she said.

"But hopefully they still are."

Mrs Meissner said checking the tracks was also a vital part of the day, as visitors often camped at the property, or spent time in the many bird hides scattered around.

Ian Falkenberg and Ted Meissner assess conditions at Gluepot Reserve. ( ABC Riverland: Anita Ward )

"Just recently, we found we need to really look after the tracks because of the dryness," she said.

"Cracks across the track and holes [are starting to] appear."

"Quite often there'll be a [large] hole on the clay country and it's [so deep] underneath, you just go through it," Mr Meissner said.

"It only happens when there's really bad droughts and it dries out underneath."

Survival hangs on soaking rains

Mr Falkenberg said the future of Gluepot Reserve relied on two things — volunteers and soaking rains.

"As we see these catastrophic weather patterns through the summer period start to become more frequent, we'll need to respond accordingly with the way we manage feral animals," he said.

Feathers can be found scattered across Gluepot Reserve, but rangers say the lack of birds right now is concerning. ( ABC Riverland: Anita Ward )

"Particularly monitoring bird numbers so we know what the populations are holding at, the numbers that they're holding at.

"We need some really good conditions now — good rainfall, good soaking rains, to get that sub soil moisture going.

"It drives the eco-system."