Regents versus Gliders: is it really that simple?
You may have heard news that Squirrel Gliders have been filmed eating eggs of the very rare Regent Honeyeater, and I know this must be pretty disturbing for a lot of people who clearly care about these beautiful birds. It's also been alarming to hear the reports about very low numbers of Regent Honeyeaters detected during 2015. Less than 100 birds have been sighted across SE Australia, and it may lead us to wonder if it's too late to try and save them!
So I thought it wise to share some background to these stories and paint a bigger picture that puts the recent news more into perspective.
Being involved in the National Regent Honeyeater Recovery Team meeting in mid November gave us many opportunities to share our experience and learn from the successes and challenges in our combined efforts. It was tremendous to see more of the successful breeding of Regents at Taronga Park Zoo and their highly successful release into the wild at Chiltern National Park earlier this year.
With four such releases over the past decade, the process has been well established and refined. The Zoo birds quickly find their own food, interact with the wild Regents, and even more heartening, a number of Zoo birds from previous releases had returned to the same forest one or more years later, to mix with the new cohort of Zoo birds! So this year the No of birds was raised to 77, more than double the previous release! Half the birds were radio tracked for the first three months, i.e. prior to the breeding season, and the observations were very promising.
Many nesting attempts have been observed over the course of these four releases, but in most cases the breeding success (i.e. fledging young into the wild population) has been very low. After all that effort, it was a disappointing result, so this year the monitoring was extended through the breeding season to see exactly what the cause was. You can't help the situation if you are only guessing - real information allows you to take targeted action.
A small proportion of birds were radio tracked and extensive monitoring undertaken of other birds to find where they were nesting. In addition, surveillance cameras were installed to watch the action on 10 nest attempts by Regents as well as more on other Honeyeaters' nests. The videos revealed a daunting number of threats to nesting, but also a tenacity of the Regents to try and try again after a failure.
- some Regents built their nests in unusual positions, e.g. an open stump only half a metre off the ground
- several nests were pulled apart, but it wasn't possible to say if it was by the Regents themselves, or by other competitive birds, or if it was after nesting had failed anyway
- several Regent pairs were persistent enough to attempt nesting 2, 3 or 4 times
- many honeyeater nests, including Regents, were observed to be attacked by predators: e.g. Magpie, Currawong, Kookaburra, Goanna, Raven, Squirrel Glider, Sugar Glider, and even Sparrow.
The media reports seemed to focus mainly on the Gliders, but this was simply because it was the first time they had been observed taking Regent eggs. In fact the bigger picture is that Gliders are really only a part of the problem, and all these predators have always made a living out of birds' nests. The research didn't attempt to blame Squirrel Gliders, rather just to find what the breeding problems actually were, and thus inform future management actions that will help the most.
One comment from the National Recovery Team was that some of the Zoo birds appeared to be not very "street wise", building their nests in exposed situations that looked unlikely to succeed. The idea came quickly that Zoo-bred Regents should only be released if they've completed a successful breeding at the Zoo. Great concept, but requires birds to be kept several more years in captivity and many more aviaries to fund. This discussion continues.
For comparison, recent observations of wild Regents in Capertee Valley NSW, did find some successful fledging, which lead me to wonder if experienced birds can hide and protect their nests more effectively. But the overall nesting success was still low unfortunately and Gliders were also observed preying on Regent eggs. Back at Chiltern VIC, a well-hidden nest in the dense shrubbery of a home garden, looked likely to be safe, but that nest also failed!! There are clearly many unknowns...... The media report was understandably only a part of the story, but it generated some responses about getting rid of Squirrel Gliders, and queries about removing their nest boxes. But we'd also have to remove Magpies, Currawongs, Kookaburras etc, and also consider the competition for nectar by Honey Bees that sometimes go wild into the bush. We wouldn't want to eradicate any of these species - removal is clearly not a goer.
Thinking laterally, we have other variables to manipulate:
- planting understorey around remnant trees will boost the protective cover for woodland birds like Regents
- this eases the intense competition with aggressive birds, so give Regents more share of the available food
- adding nectar-rich trees and shrubs to remnants also makes the habitat more productive overall
- these actions combined can give Regents not just reduced competition, but also a richer food resource
- Regents should survive more easily to another year, and hopefully return with more "street wisdom"
In the Lurg Hills we have 20 years of planting experience behind us, doing exactly these things to help a whole range of threatened woodland birds. And long-term surveys show that the birds are responding! Grey-crowned Babblers have bred up by 240% over the past decade, and our sites have many woodland birds within 4 or 5 years after planting. In fact the number and diversity of woodland bird species increases with the age of our sites, and the number of aggressive Noisy Miners decreases from 2 to 6 years after planting.
And the predators have been out there all this time....
It seems our long-term strategies for Regent recovery are showing definite signs of success. Asking for some verification from the Flora and Fauna Guarantee Officer of DELWP, I was reassured that our strategic thinking matches his understanding well. Asking for the National Recovery Team for feedback on our restoration works, I was reminded that the birds are in fact using our habitat sites, "so keep on with your good work". The original Recovery Team leader also confirmed that he has every confidence in the experienced judgements we make, on both habitat site choices and restoration actions.
I also sought feedback from the DELWP planning officer in charge of monitoring at the Chiltern Regent Releases. It was good to hear that he sees Lurg as a much more productive foraging habitat for Regents compared to 20 years ago, but cautions us to be mindful of its breeding potential as well!
Given that Regents routinely move 4-15 km in a day, and certainly over cleared paddocks, connectivity at the small scale required for Gliders, is not necessarily required for Regents, and could be even counterproductive in breeding situations. Leaving some rich breeding habitats disconnected from other habitat areas is a very sensible strategy.
As for the low No of Regents sighted this year, we know the birds range widely across SE Australia, so can only conclude that they have found somewhere else to hide during the abnormally dry seasons. There are so many places to search and so few people out searching, so it's not surprising to detect so few. Finally, Regents have a habit of remaining very quiet and secretive, even when they are known to be present. We're not giving up just yet!!
Ray Thomas, Regent Honeyeater Co-ordinator.
22 Dec 2015