By Romy Stephens
As Victoria’s population continues to expand at a rapid rate, it might leave you wondering what happens to animals within the habitats we encroach.
This becomes of particular interest across the eastern and south-eastern suburbs of Melbourne, where nature reserves and national parks are increasingly competing with the need to accommodate more people.
According to a recent study led by Monash University, species inbreeding due to habitat destruction is taking its toll on native birdlife, right here in our backyard.
The research, published in Current Biology, suggests that the Helmeted Honeyeater would likely be extinct due to inbreeding if it weren’t for conservation actions and habitat restoration efforts.
Professor Paul Sunnucks from Monash University’s School of Biological Sciences, who led the study, said the findings have wide-ranging implications for wildlife management.
“Our study combines over 30 years of demanding fieldwork and advanced genetics to quantify how much harm is done by inbreeding in the last wild population of the Helmeted Honeyeater, and identifies ways forward,” he said.
The Helmeted Honeyeater, named for its ‘helmet’ of head feathers, is a much-loved Victorian state emblem found only in the Yellingbo Nature Conservation Reserve.
The species was once widely distributed across eastern Melbourne but since European settlement, 99 per cent of the floodplain forest essential for the birds has been wiped out to make way for agricultural land and towns.
As a result, only 50 wild birds remained in 1989.
In an effort to study the birds and restore numbers, most Helmeted Honeyeaters have since been given coloured leg-bands for tracking. This allowed researchers to record a detailed account of how long each of the birds lived and how many offspring they had in their lifetimes.
By combining this information with advanced genetic analysis, the research team determined the damage caused to Helmeted Honeyeaters by inbreeding.
The most inbred birds’ reproductive success was typically 90 per cent lower than the least inbred.
According to Monash researchers, habitat destruction often results in wildlife populations that are small and made up of low genetic variation.
The harmful effect of this is known as ‘inbreeding depression’ where species typically have a shortened life, become a poor breeder or even die.
Despite the findings, researchers claim that 30 years of conservation efforts have managed to help the birds get back on their feet.
Since 1989, numbers in the Yellingbo Reserve have steadily increased and it’s estimated there are now 230 birds living there.
A program that has been instrumental in restoring bird populations is the captive breeding initiative at Healesville Sanctuary.
The program began in 1989 and is still operating today. It involves pairs of Helmeted Honeyeaters, with each pair in its own purpose-built aviary. Each year, most birds bred are released at reintroduction sites in Yellingbo.
Kim Miller is the Life Sciences Manager, Conservation and Research at Healesville Sanctuary and one of the report authors.
She said the captive breeding program has come a long way in recent years.
“We have dedicated keepers who look after the Helmeted Honeyeater. They form pairs and start their breeding season in August and that breeding season goes through until March and sometimes April,” she said.
“It was initially established due to the small and declining population in the wildlife.
“The program, like all of our programs for threatened and endangered species, has certainly evolved.
“The amount of planning has expanded over the last 30 years. We have come a long way in our thinking.”
Monash researchers have suggested that while inbreeding depression is still a problem, it can be reduced by cross-breeding with a closely-related population – something that is being trialled at the Sanctuary.
It involves cross-breeding Helmeted Honeyeaters with the closely-related Yellow-tufted Honeyeaters.
“Even as recently as 30 to 40 years ago there was some level of gene pool mixing between these two subspecies,” Ms Miller explained.
“Simply due to isolation, the mixing of these gene pools has stopped.”
Despite such positive advances in the research and conservation space, there are still concerns for the species.
It is currently listed as critically endangered under the Environment Protection and Biodiversity Conservation Act 1999.
Friends of the Helmeted Honeyeater is an organisation that was formed in 1989 to help protect the bird species.
The group, which celebrated its 30th anniversary in May, is based within the Yellingbo reserve.
It works to improve the species’ habitats and increase community awareness throughout the local area.
Both the organisation and Healesville Sanctuary are trying to not only improve the birds’ habitat at Yellingbo but also expand areas in which Helmeted Honeyeaters are found throughout the eastern region.
Friends of the Helmeted Honeyeater’s Environmental Coordinator, Dr Melanie Birtchnell, said one of the biggest difficulties is trying to work with landowners that surround Yellingbo.
“There’s a lot of strategy in trying to reconnect Yellingbo with the broader damaged landscape,” she said.
“There are currently paradigms around agricultural land versus conservation values.
“It’s not necessarily population as it is about competing values.”
But Ms Birtchnell added that people around the area are on board with collaborating to protect the Helmeted Honeyeater, it’s just a matter of knowing how they can help.
“People want to help, but they don’t know how so it’s about education,” she said.
“Usually, people are horrified to find out that their actions are having an impact on threatened species.
“Most people really want to be on board with conservation… when they get a bit of information they want to help.”
To find out more about how to help the Helmeted Honeyeater visit the Friends of the Helmeted Honeyeater website, www.helmetedhoneyeater.org.au or call Healesville Sanctuary on 1300 966 784.