Superb parrots have enjoyed their best breeding season in the ACT since a government-funded monitoring program began in 2015, bouncing back after two years of diminished breeding output.
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The vulnerable birds appear to have adapted to the development of Throsby, in Canberra's north, by selecting nest trees further from the urban edge, prompting researchers to stress the importance of conservation buffers to protect native wildlife and their breeding habitat.
ACT government ecologist Dr Laura Rayner said breeding superb parrots produced an estimated 39 offspring in woodland adjacent to Throsby in 2018.
The result was consistent with that of 2015, when 38 fledged young were born.
But the number dropped significantly in the two years that followed, with breeding superb parrots producing just 13 offspring in the Throsby area in 2016, and 20 in 2017.
"Essentially what we are seeing in these values is that superb parrot breeding output declined in the year that [Throsby] was created, but has since recovered, with 2018 being their most productive year since the start of our monitoring," Dr Rayner said.
She said a combination of things might have contributed to the two-year breeding decline, including disturbance from earthworks and seasonal factors.
Data from the monitoring program shows that the birds returned to trees previously used for breeding just 55.6 per cent of the time last year, down from 85.7 per cent in 2017 and 80 per cent in 2016.
Superb parrots' nesting hollows were also an average of 78 metres further away from suburban boundaries last year than in 2015.
"Interestingly, the trees that they've used in [2018], when they've recovered their productivity, appear to be trees that we haven't seen them breed in in previous years," Dr Rayner said.
"That's critical and it's a good news story because it shows that the species is capable of adapting, but it's a cautionary message because it shows that if we are to develop next to a breeding colony, there's a chance that they need a bit of a minimum distance from that disturbance to breed effectively.
"Unless they have that space to move into and find new nest trees, they might be pressured in a way that would compromise their productivity."
The monitoring program has also looked at superb parrots' breeding output in the Molonglo Valley in the last two years, with the birds producing 35 offspring in 2018, up from 22 the year before.
Dr Rayner, who spends most of her time between September and February scaling centuries-old trees to look for superb parrots' nesting hollows, said it was reassuring to see the species' breeding output on the way back up as the birds face two major threats.
She said the woodland habitats superb parrots relied on were listed as critically endangered, while Australian National University research currently under way suggested that climate change may also significant reduce the migratory birds' natural range.
"The predictions are absolutely chilling. They’re concerning," Dr Rayner said.
"It’s suggested that in the next 50 years, their range is going to contract about 90 per cent, mostly in the northwestern part of their range around northern NSW."
Dr Rayner said this was likely to result in superb parrots concentrating more around the ACT region, meaning that while Canberrans might start to see more superb parrots, that didn't necessarily mean the population was increasing.
"We’re looking down the barrel of having more birds becoming reliant on less habitat and less space," Dr Rayner said.
"If those climate change predictions come true for the species, what we are facing is that one of the areas they are likely to be able to persist is here.
"We’ve got maybe 50 years to make sure that we can provide and protect enough woodland habitat that contains enough big, old trees with hollows of the right dimensions.
"Canberra’s always been important for superb parrots because they breed here and anywhere a threatened species breeds is an important landscape, but it’s doubly important in thinking that we may see more birds in the ACT."
