In the early 1990s, kea were surveyed in the 6000 hectares around Lake Rotoiti, and there were 11 breeding pairs producing an average of 10 fledglings per year. By 2010, a survey over an expanded 13,000 hectares turned up only two breeding pairs. This is a classic problem with territories and total areas too large for affordable pest control. It’s quite reminiscent of the situation with whio/blue duck, where many km of trap lines are required to protect the range of a single pair. DOC’s Grant Harper and David Rees wanted to try localised pest control around nest sites: find the nests each season and move in with a perimeter of traps.
We bought some traps for the project, and nests were located and monitored with video cameras. In 2011 two of the three nests were cleaned out by possums. It was a similar story in 2012, with stoat predation being observed. This is not a happy outcome, but the idea is a good one and the team will keep trying, with help from a strong local conservation group, to stop another local extinction of kea.
Photo credit: Corey Mosen, DOC
Alarmist? Maybe, but we have long been concerned about the state of rock wren, and Megan Willans imparted some bad news in February 2013.
Megan checked out the intensively-trapped area in the Murchisons, and adult rock wren were seen where expected. However, Dan Palmer, Jo Hoare, Colin O’Donnell and Antje Leseberg monitored 21 nesting attempts in the Homer and Gertrude areas, and all failed. They confirmed stoat predation at at least 9 of the nests, and mouse predation at at least one. (And who knows what happened to unmonitored populations not benefiting from 1080 application in the mast event just gone?)
These results make it even more important that the translocation to Secretary Island in 2008-2010 funded by Fauna Recovery NZ will prove successful. Pleasingly, the 2013 survey on Secretary turned up no fewer than 62 unbanded birds. There were also at least three banded ones living on from the founder population established in 2008-2010. The survey also showed rock wren descending into lower-altitude areas of suitable habitat, indicating the island might have pretty decent ultimate carrying capacity. This is important because there are not really any other islands to try, unless we have another go on Anchor, or get radical and try an island with lowland habitat only, hoping that these subalpine specialists can niche-hop. Rock wren as surrogate for the extinct bush wren? That may well be getting ahead of ourselves, and I do have a little worry in the back of my mind about how few founder adults were found on Secretary. It should have been a bit higher, and it’s possible this might indicate the population oscillating, with some seasonal factor causing greater mortality than normal. Stoat numbers evidently continue at stubbornly high(ish) levels despite all the effort being put in to this big island. Time will tell.
So, yes, I think rock wren are hanging by a thread, and we hope the Secretary work is enough to avert disaster while other solutions are found.
John Heaphy reports that transfer of captive-raised OFPs continued right through to 2014, with around 150 birds in total released on Tuhua. The birds are establishing and breeding, but numbers are not exploding by any means, which is a bit of a repeat of other OFP translocations. However, with that number moved, we must hope that a viable, genetically diverse population will remain on Tuhua, and not require ongoing management. There seems no obvious reason why the island is not full of parakeets by now, apart from a mite outbreak in 2013 which seems to have run its course.
John noted also some milestones with the project. In 2013 he photographed the first Tuhua-bred bird, herself breeding, with one of the older translocated males. John was also especially pleased that several pairs took to the nest boxes he installed, as he had his doubters that this attempt to extend the range of breeding sites would work.
It was early in the piece that we decided Puangiangi needed to be given a fair shot at becoming the seabird island it once was. Our minds were focussed in December 2012 when we discovered sooty shearwater visiting one of the speaker sites.
Weka are known predators of seabirds, and are well known to attack chicks in their burrows or nearby. We now have lots of film of weka trying to get into the shearwater burrows on Puangiangi. Peter obtained a permit to remove weka from Puangiangi and to translocate them to the Garne and Saville Scenic Reserve about 30 minutes by car from French Pass on the mainland, which should be far enough away that they don’t swim back.
Weka were very obvious on the island when we arrived to begin the project in May 2012. My ultra-scientific estimate put the population at 20. We find that weka are drawn in to the field centre where they are attracted by food, shiny new plumbing fittings and for some reason my dive booties which they love to drag away. Through hand netting, cage trapping and even grabbing one while it was poking through our gear on the landing beach, we have caught 97 of the 20 as at June 2015. Encouragingly, the catch and encounter rates are much lower now, but we still know of one or two on the island. We can hear them calling from Tinui (where the population must be at carrying capacity), and Peter is aware of one on Wakaterepapanui, but we have no idea of the re-invasion rate if any from the other islands in the group.
January 2013- Trustee Sue Freitag was looking forward to her trip to Waikawa/Portland Island, to help uplift shore plover eggs for transfer to Pukaha/Mt Bruce. There the chicks would enter the breeding program and improve the genetic diversity of the birds being pumped out to the various reintroduction projects around the country. We were upbeat about the second year of our financial involvement in this important project involving DOC and the private owners of Waikawa. Unfortunately a scene of near-devastation greeted the landing party, with 60 of 82 adult shore plover missing, a fifth of the world population. Dead birds of other species had the hallmarks of stoat predation, although emergency searches with trained dogs did not turned up stoats or rats. Project leader Helen Jonas from DOC and Sue agreed quickly on redirecting funds to a rescue mission, and all 12 eggs from the 5 nests found have been taken off. Nine hatched and the chicks were raised at Pukaha (in facilities upgraded using Fauna Recovery NZ funding) and the Isaac Wildlife Centre.
In their natural stronghold on Rangatira in the Chathams, shore plover are under constant aerial attack from skuas, but can still stay alive and protect their chicks. They are ill-equipped to fight rats and stoats though and regrettably are very much the sentinel species that first indicates predator incursion onto our island sanctuaries.
By March 2013 the situation was even worse with the population down to 16, and such birds as could be were caught and removed to captivity. The team carried on with trapping and looking for rats or stoats, and the remaining shore plover largely held on and began to breed in the following Spring.
By February 2014 it was thought that the predator was dead, although not found, and tentative reintroductions were begun. In May some hair and scat samples collected on the island were confirmed as belonging to a Norway rat. By July the season’s releases of juveniles were complete, with the population standing at 18.
In March 2015 another 20 juveniles were moved on, but then a rat was caught in a trap. Intensive searching and trapping has not turned up any more and 46 shore plover went into Winter.
Thanks to Helen Jonas for her regular updates and to Denise Fastier for the photo. Fingers crossed.
Are shore plover the next conservation disaster? Shore plover are hyper-susceptible to predator incursions, and establishing new populations is very slow because of high dispersal rates. What do you think about sending a batch down to Campbell Island- they won’t fly back from there, there is suitable habitat, and it should remain predator-free barring a shipwreck.
January 2013- Mike Ogle reports in from our 2006 project to assist with translocating weka to Totaranui: “The weka numbers there have very quietly been increasing and spreading to surrounding catchments…And their future is looking bright with more stoat trapping planned through Project Janszoon and Abel Tasman Bird Song Trust. Quite a delight to holiday there with the family and have weka to feed.”
Peter adds that weka are getting more common in Nelson City even- he has no obvious explanation but we’ll take good news even if we can’t understand it fully.
December 2012- Our surveillance camera has picked up activity at the hoped-for seabird colony only a month after the first speaker system went in. The above was sent to a cellphone back in Wellington showing a sooty shearwater landing?/exercising? at 1 AM on 3 December. The speaker is at top right.
These seabird-attracting systems are fast becoming standard practice and they are helping, unsupervised, to found colonies of burrow-nesting seabirds- the keystone species of any self-respecting seabird island- in many locations. Fauna Recovery NZ is now up to its 6th system, including one on Wakaterepapanui, next island up from Puangiangi. Sooties were certainly on Puangiangi late (1980s/1990s) into Ross Webber’s tenure and it’s reasonable to assume that they lasted longer than the smaller shearwaters, petrels and prions in the face of rat predation. Peter and I had a good look in May 2012 for any activity at the old burrow sites, and everything looked long-abandoned, with no tell-tale cleared areas around the burrows, or seabird smell. On that basis our conjecture is that the speakers might well have been responsible for these sooties coming in for a look around.