The Mallee emu-wren are sought after by bird watchers for their long tail feathers. (Supplied: NRSA Murray-Darling Basin)
A tiny bird species wiped out by bushfires in South Australia is surprising ecologists by how quickly they’re breeding, after a small number from Victoria were successfully reintroduced.
The Mallee emu-wren only exists in two core locations in Victoria and South Australia.
When lightning in 2014 sparked two bushfires in the Ngarkat Conservation Park, nearly 300km south-east of Adelaide, it was believed the park’s emu-wren population had been wiped out.
The loss of habitat had left the birds “functionally extinct” in South Australia, according to Chris Hedger, an ecologist with Natural Resources SA Murray-Darling Basin (NRSA).
“We could never officially say they were extinct because there’s so much habitat out there,” he told ABC Radio Adelaide’s Saturday Breakfast program.
“But we were very confident that if there were any individuals left, it was functionally extinct and would not be able to survive in the long term.”
In April this year, 38 of the birds were translocated to Ngarkat from a national park in Victoria’s Mallee, where a breeding program had been underway to bolster numbers amid fears another bushfire could knock them out altogether.
Another 40 were sent in August from Victoria’s Murray Sunset and Hattah-Kulkyne national parks.
“For many birders, or twitchers, who like to go to Victoria to look for birds, those two parks are often frequented, particularly because they’ve got good, high levels of diversity, particularly for Mallee species,” Mr Hedger said.
Emu-wrens found to be breeding
NRSA said the birds had recently been surveyed and a significant number of paired birds with fledglings had been found.
PhD students Will Mitchell and Simon Verdon tracked them with some difficulty, as the elusive birds weigh just 5.5 grams and prefer dense, inaccessible scrub and tussocky grass.
“That’s pretty amazing considering they must have started [breeding] almost within days of being released at these completely new sites,” Mr Hedger said.
The emu-wrens also surprised the team when three adults were found to be raising fledglings in cooperative breeding behaviour previously unseen among the species.
“They’ve surprised us quite a lot, given that they’re a small species and we think they must be really fragile and vulnerable.
“In many respects they are, but they are just such a tenacious little species.
Mr Hedger says the birds’ calls to each other during transit were surprisingly loud. (Supplied: NRSA Murray-Darling Basin.)
“We never had any issues feeding them as we were transferring them through to the sites; they were just voracious.
“If you put anything in front of them that looked like an insect they would just destroy it, so I think they’re a little tougher than we think they are.”
Long tail feathers inhibit flight
The Mallee emu-wren, which is related to the superb fairy-wrens common in southern SA, are restricted in where they can live and Mr Hedger said their habitats had already been reduced before 2014 due to bushfires and drought.
They are highly sought after by bird watchers, who are keen to spot the male’s striking ochre and sky-blue colours, and the birds’ long tail feathers are about twice as long as their head-body length.
“They look like emu feathers and are quite coarse and open … and are definitely not made to fly,” Mr Hedger said.
“They actually inhibit their flight ability quite a bit.
“They’re a bit like chickens; they can only fly for a set period of time before they need to set down again.”
It can be hard to track Mallee emu-wren due to their preferred habitat and elusive behaviour. (Supplied: NRSA Murray-Darling Basin)
The team did not know how vulnerable the species were to other pressures and are keeping the translocation location in Ngarkat secret until the birds become established.
Mr Hedger said that after bushfires, the biggest threat to their survival is drought, so water availability was taken into account when choosing the relocation sites.
“We were really careful about not necessarily choosing sites in the northernmost part of their range, historically,” he said.
“We weren’t picking sites that might drop out under climate change scenarios.”
Another 200 birds to be translocated
Mr Hedger said the team would continue to monitor the release to ensure the emu-wren survived long term.
“Certainly the fact they are breeding is a good indicator of what we might expect,” he said.
“These 78 birds are what we call phase one of the translocation process and we’ve made it a bit experimental.
“No-one has ever moved this species, and if they have moved a similar species, it certainly wasn’t in the numbers we’re talking about.”
Mr Hedger said phase two would involve supplementing the existing population with a further 200 individual birds translocated to Ngarkat.
“They might move to different locations, but the idea is to get a really strong, prosperous community of emu-wren there.
“[After] phase two they can go forth and prosper in the decades to come.”