The swift parrots need our help. This endangered parrot, dependent on tree hollows in old Tasmanian trees, has been in serious decline as the forest landscape is altered. Breeding only in Tasmania, it has been the subject of ongoing research and community conservation. Earlier this year, the public was surprised and shocked to hear that illegal forest logging had destroyed critical nesting habitat, and a team of Victorian arborists realised they could contribute their skills. As a swift response to help the swift parrot, an expedition to Tasmania was planned by the Victorian Tree Industry Organisation to help build emergency nesting habitat.
Working with chainsaws and tree health, the arborists are uniquely experienced in the long term growth and structure of living trees. I was fortunate to join on the fieldwork on Bruny Island and help out as ground-crew while branches were carved into the size and configuration preferred by nesting swifties, and to learn a bit about the practice and theory of artificial habitat creation.
Grant Harris, of Ironbark Environmental Arboriculture/ Tree Climb Australia, shared his thoughts on the project: ‘We’ve use this technique of artificial hollow creation with the Major Mitchell’s Cockatoo in North-western Victoria; where we had very promising results. So I’m optimistic for success of this project.”
‘One advantage we have is the years of data on natural Swifty hollows, collected by Dejan Stojanovic and his team at Australian National University” he continued. “This data is extremely valuable as it gives us direction on the dimensions of the hollows we should be creating, to meet the Swifties breeding needs.’
Pat Kenyon of Tree Tactics recalled his work developing and championing the hollow carving technique:
In 2009, Philip Kenyon (Dad) and I started playing with the idea of carving hollows with chainsaws, this was mainly done on the end of branch stubs, we also met James Smith at Tree Net in Adelaide where he did a presentation on habitat and hollows in trees. I had done a reasonable amount of research into what sizes to create hollows but struggled with information off our Local Government Bodies with receiving any clear information (in Arborist terms) as to; height above ground, orientation or how big to create hollows and entrance holes.
After the 2009 fires the concept of habitat stumps became a real hit due to hundreds of thousands of trees needing to be removed. It became common practice for Councils to leave habitat stumps behind as it was cheaper to do this than remove the whole tree. The only part that Councils didn’t realize was that it can take up to 50 years or greater for a hollow to form, there are now thousand of solid upright logs left on road sides as habitat stumps that have little more value than perches.
This is when the idea of habitat hollows really began. In 2010, Philip Kenyon and I did a presentation on how to create hollows at TreeNet, Adelaide. I caught up with James Smith there again and he gave me a range of modifications for our hollows and some science to develop these hollows further so they would successfully work. The most significant changes to make was locating the entrance as far from the bottom as possible rather than in the center, sloping bases so that they would drain and not cleaning out all the rough edges so that chicks can climb out.
With James Smith’s input we also came up with the Bat Maze, various forms of aquatic and ground based habitat that can be created in a matter of hours so you do not have to wait 50 or 100 years for them to decay and become useable. James also created the “Hollows for Habitat Guidelines” and put them into practical sizes that we could cut with chainsaws and provided an Orientation Chart which he made available on the VTIO website.
Since then we have run Habitat Creation workshops in, Victoria, Adelaide, NSW, Northern Territory and Queensland. With all of these workshops we have had plenty of positive input and feedback from people attending, and with every workshop we have made advances on the design and construction technique.
It been great to see the enthusiasm from everyone at the workshops and to change their views from cutting trees down to how they can keep them for creating habitat. From starting with the concept until now I have been directly involved in carving more than 200 hollows across Victoria.
Grant expressed his surprise at how well the expedition turned out: ‘I’m overwhelmed by the response of the VTIO members, it’s just fantastic! We’ve got over thirty professional arborists giving their time, providing their own equipment and sharing their skills. We’ve also had amazing support from the local community; it’s really a privilege to be working in such a beautiful place’.
‘We’ve installed over sixty artificial hollows, which it a great effort from the VTIO vols. This is the first step, the true measure of success is to see if these artificial hollows produce Swifty fledglings. It’s important to recognise this technique [artificial hollow creation] is a short term fix…a band-aid for hollow dependent species. It’s not a long-term solution or a substitute for conserving forests, which are managed to allow the development of natural hollows.”
YD Bar-Ness is a conservation ecologist based in Fremantle, Western Australia, on a long-term quest searching for the Kalpavriksh, the Wish-Fulfilling Tree of ancient Indian myth. He hasn’t found it yet, but will make sure to tell you when he does.
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