Rainforest birds in decline in black summer bushfire aftermath

Functional bird populations vital to rainforest regeneration are struggling to recover in the years after the black summer bushfires devastated Australia, according to a study from the Centre for Ecosystem Science at UNSW Sydney.

The study, published in Global Ecology and Conservation, investigated the impact of the 2019-2020 Australian bushfire season on the ancient Gondwanan Rainforests of Australia World Heritage Areas, of which the Barrington Tops is one, which were burned for the first time in recorded history.

The researchers found that unprecedented megafires negatively impacted the diversity of functional rainforest bird communities among burnt areas of the Gondwanan rainforest compared to surviving regions, as well as adjacent dry sclerophyll forests – woodland areas characterised by hard leafed and drought-adapted vegetation.

“We found that the number of functional species, but also the relative abundances of species, was lower in burnt areas compared with unburnt areas across five national parks surveyed within the World Heritage Area,” says Josh Lee, the study’s lead author.

With their size, duration and intensity, the 2019-20 blazes were some of the worst in bushfire history. For the Gondwanan rainforest, it was especially devastating, wiping out an estimated 50 per cent of the already scarce habitat.

“These rainforests are 40 million years old, and the fact we’ve burned up to half of it in just once fire season – which we can confidently attribute to climate change – is astounding. It’s another page in the story that is the huge impact we’re having on unique ecosystems worldwide,” Mr Lee said.

The study found the most affected rainforest birds were species that eat insects, leaves or fruit. Of particular concern were fruit-eating birds such as the wompoo fruit-dove and paradise riflebird, that have significant roles in rainforest regeneration.

Related: World heritage areas facing growing threat, the Barrington Tops included

“We found there were fewer fruit-eating birds in the burnt rainforest than the unburnt areas, which is potentially a bad sign because it might mean that there’s less of that rainforest regeneration happening,” Mr Lee says.

“These fruit eaters disperse rainforest seeds over large distances. Rainforests need these birds to eat and then disperse the seeds for them to grow in other parts of the rainforest. If we don’t have the pigeons and doves to help the fire-affected areas of the rainforest regenerate, we are in real trouble.”

Because of the impact on seed-dispersing birds, the recovery of the rainforest is likely to be extremely slow and highly dependent on the emigration of animals from outside burnt areas.

“The evolutionary lineage of these rainforests is that they’re typically wet, which means their species aren’t used to exposure to fire and just aren’t well adapted to recover in general,” Mr Lee says.

The researchers say the findings indicate that no environment is safe from the direct and indirect impacts of climate change.

“We are particularly concerned about the ramifications of increasing drying with climate change and more intense bush fires on our really fire-sensitive forests and their animals,” says Associate Professor Will Cornwell, co-author of the study.

“Because of just how unique these ecosystems are and how rarely they burn, we really don’t know much about what the recovery will look like,” Mr Lee says.

“It remains to be seen what the impacts will be in years to come or whether the rainforest and the birds will come back at all.”