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Category: Weeds
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I have recently returned from a 2 week trip to Lord Howe Island.  Lord Howe Island is the remnant of a much larger volcanic island approximately 600km east of Port Macquarie.  This was an exciting time to visit because rats have recently been eliminated from the island.  Indeed the island is a success story of ecological management (at least in the last couple of decades). The majority of the island is in a 'Permanent Park Preserve' under the Lord Howe Island Act, similar to a National Park.  The vegetation is quite tropical, at least to my eyes.  It is very beautiful.

The Island was permanently settled in 1834 after being used as provisioning port for the whaling industry.  It is thought that unlike Norfolk Island (further east), Lord Howe Island was never inhabited prior to European settlement.

We went to join the Friends of Lord Howe Island on a 7 day weeding trip, and spend a few days either side of that to explore.  We had heard of the weeding trip from friends who had done it before, and organised a group of 8 friends to go.  The weeding week turned out to be not that taxing, and very rewarding, with a few hours weeding in the mornings, an afternoon guided walk, a presentation in the evening from an expert, and then dinner together at one of the island's restaurants.

But get this:  the weeding needed by the friends has reduced considerably, as the Lord Howe Island Board (LHIB) is running an effective weed eradication program themselves!  (Don't get me started on the totally inadequate efforts many municipalities on the mainland, at least in Victoria, are making).  The program is based on a Weed Management Strategy published in 2016. The island is divided into grids which the weed eradication team visit every 24 months or more frequently when the weeds present demand it.  Each grid is systematically searched and target weeds removed.  According to the LHIB, over 129,000 hours of grid search weed control method has been undertaken since the program was started 10 years ago, at a cost of $6.4 million.  The Board directly employs its weed control staff, but also contracts in helicopter-mounted weed sprayers to control target weeds on inaccessible areas (often vertical cliffs). 

The Lord Howe Islands Group is listed as World heritage for its unique landforms and biota, its diverse and largely intact ecosystems, natural beauty and habitats for threatened species.  It is also on the Australian National Heritage list, and the New South Wales State Heritage Register.  These well-deserved listings presumably make it easier for a very small island to get funding for expensive conservation programs.

After flying in, on the way to our accommodation I was thrilled to see rare and endangered Lord Howe Island Woodhens hanging out on the roadsides, doing very well thank you after the recent rat eradication program.  Rats competed with the woodhens for food.  Woodhens were a near miss in terms of extinction, but nine terrestrial birds, one bat, and at least four invertebrates have become extinct since 1778.  Four bird species are thought to have been caused by human hunting or shooting to protect crops.  But the accidental introduction of rats in 1918 is thought to have triggered a second wave of extinctions including 5 bird species and the Lord Howe Island Stick Insect, and threatened a number of other species including the Woodhen.

Feral pigs, cats and goats were eradicated by the early 2000s, but controlling the rats was a much bigger challenge.  Tasmanian Masked Owls were introduced in the 1920s to control the rats but didn't, instead pushing the Lord Howe Boobook to extinction.  Rat control in the settled parts of the island using baits was carried out by the Board ongoingly until a $15.5 million program in 2019 using intensive ground and aerial baiting across the whole island.  Part of the program involved rounding up the remaining Lord Howe Island Woodhens and and a number of other species into a captive breeding enclosure while the baiting was carried out.  Since their release, Woodhen numbers have been climbing quickly.

During the weeding week a beetle expert Dr Chris Reid often accompanied us, and gave us a talk one evening.  He was on the island to do a post-rat survey of the beetles to compare to his pre-rat surveys.  Prior to analysis being complete it was clear that a number of beetle species were considerably more common than they were prior to rat eradication.

Locals told us that since the rat eradication, berries could be seen on bushes, and seeds on the palms that would normally be quickly eaten by rats were persisting on the trees.  They also pointed out the drastically increased level of germination of native seedlings in the forest.  This was especially noticeable with the Kentia palms and also the Pandanus, where seedlings were present and so were mature plants, but there almost no 'teenagers'.

With the absence of rats it becomes possible to consider re-introduction of species to the Island that were made extinct by the rats.  Or if not the exact species, then closely related island species.  Ian Hutton, curator of the Lord Howe Island Museum identified a number of potential bird species that could be introduced as proxies for lost species.  One species whose reintroduction program is well progressed is for the Lord Howe Island Stick Insect, made extinct on the main island by rat predation but rediscovered on Ball's Pyramid a rock stack 25 km south.  A small number of these stick insects were collected alive from Ball's Pyramid (an impressive feat in itself) and have been bred up at Melbourne Zoo in preparation for reintroduction.  The first stage is likely to be on Blackburn Island a mere kilometer off the main island.  One of the 'weeding' days was actually spent on Blackburn Island planting habitat for the Stick Insect.

A less happy consequence of the rat eradication I think will be the proliferation of seed-spread weeds.  For example I noticed that Ehrharta erecta was common along the edge of walking tracks, but not in the forest.  To some extent they may have been suppressed by the rainforest canopy, but in my experience Ehrharta doesn't mind a bit of shade.  I suspect that Ehrharta can now reproduce much more easily now that rats aren't eating their seed, and the species will become very destructive.  Other weed species that rely on seed spread also may suddenly now become a problem.

The week-long weeding trip idea struck me as something that could be used as a model and applied elsewhere.  Participants pay for a package that includes airfares, a week's accommodation, dinners and one lunch, weeding tools, transport from the accommodation to the work sites, guided walks and talks.  The total cost is discounted below what a normal tourist would get (I presume there are group booking opportunities, and our trip was in shoulder season anyway).  There was a lot of emphasis put on socializing, and on learning, not just on slaving away with the weeds.  Proof of the program's popularity is that many of the 22 participants were repeat visitors, some had done the program 10 or more times.  I think it needs a dedicated organiser (thanks Ian Hutton for being our organiser and host!), access to local experts prepared to share their expertise, accomodation providers prepared to take groups and give discounts, restaurants prepared to take group bookings, a charismatic leader, equipment for the weeders, and a way to dispose of weed material that can't be left on site.  Probably it also needs a marketable destination also.  I'm interested in your thoughts on this.

While we were there some of our group including me paid for the guided walk up Mount Gower, the tallest peak on the Island.  The walk is reputed to be the hardest day walk in Australia. It was an exhausting walk, with many sections requiring hauling ourselves up steep sections on fixed ropes and lowering ourselves down again on the return journey.  But a very rewarding trip nonetheless. The forest on top of Mount Gower is a dwarf cloud forest, as much of the time (and in the photo above) Mt Gower is capped by cloud.  Fortunately when we were there it was cloudless and we got a spectacular view north across the island.

We booked our trip through Oxley Travel, who specialize exclusively in Lord Howe Island and Norfolk Island (I receive no kick back for mentioning them here).  We flew to Sydney, and then direct to the Island.  But you can also fly from Port Macquarie.