It was another odd breeding season for the sooties. For our first burrow check in early December 2017, we were joined by Jo Sim, Brook Mells and seabird specialist Rua. The southern colony had 23 active burrows, and the sniffer team found two new small colonies of 7 burrows in all, 5 of which were confirmed to contain sooty shearwater. None of the hoped-for smaller petrels were found despite a comprehensive look over the island (Jo recorded the search track with her GPS and plotted it for us). Later we moved the less active of the two petrel speaker set-ups, with flutterer decoys, to a new site reminiscent in aspect of the colony on Long Is., and looking out to where flutterers feed and raft up at times. Flutterer visits have since been recorded on camera, scattered throughout the winter. There appears to be no nesting.
All or most of the sooties were present in January 2018, and by February the main colony held 11 chicks and 1-2 adults. In mid-April 2018, the last check before fledging, there were only 4 chicks; these are presumed to have gone on and fledged. There had also been one killed at the burrow. Only feathers were left and it looked very much like a falcon kill (Richard Cuthbert in his book Seabirds Beyond The Mountain Crest records falcon taking Hutton’s shearwater at the burrow). There was also a dead, partly feathered, chick at one of the outlying colonies, out of the burrow and very early to be so. Perhaps this indicates that the adults were not getting enough food at sea and gave up on the chicks, prompting one at least to attempt to fledge early.
I found it very worthwhile to get some canine input to our seabird effort. The sooties may always be difficult as they are elsewhere in the area, and it’s now clearer that we don’t have a decent, undetected colony of fluttering shearwater, fairy prion or diving petrel. We continue to ponder how to get one of those up and running.
After last season’s good result, it was looking very promising in January 2017 too. A record 25 burrows were active, but by February this had dwindled to five. Come mid-late April the colony was deserted, a total failure for the season. We saw nothing untoward at the colony during the season- little or no weka activity, no disturbance, no carnage.
Graeme Taylor at DOC says the sooty season elsewhere was average, with 40-50% of active burrows fledging a chick. He says we need to look closer to home than some at-sea event which might have affected all sites. In contrast, the fluttering shearwater colonies on Mana (communicated by Helen Gummer) and Maud (Biz Bell in the March 2017 Birds New Zealand magazine) had poor results, most likely due to burrows being flooded in heavy rain. Puangiangi also had at least a couple of deluges during the generally acknowledged miserable summer, and despite the excellent drainage at the colony, the chicks may have drowned or died of hypothermia.
In late April 2016 we checked the sooty colony again with the burrowscope. The sooty chicks would be fledging in early May and if there were healthy chicks present in late April, then they would probably have had their last parental feed and would be likely to fledge successfully.
We found 16 healthy sooty chicks, in various states of down coverage, but all looking good. Down coverage is a misleading method of aging chicks and a single wet night on the surface can turn a fluffball into a bird that looks ready to go.
Not only was 16 a vast improvement on last year’s presumed 3 fledges, it was from 20 active burrows (of 30 known burrows) at egg-laying time in late November. This is a high success rate and implies that all was well at the colony with respect to weka predation and any other adverse factors beyond our knowledge.
Weka numbers were a bit lower this year than last, but we did not see any evidence of successful weka predation last year either. I guess some at-sea event, such as food concentrations moving further south than expected, might have explained last year’s result.
Can we ease up on weka-catching therefore? Quite possibly with respect to the sooties, but not if we are hoping that any of the smaller seabirds like fluttering shearwater, fairy prion or diving petrel will establish.
Only a month after starting the Puangiangi project, we were aware of abundant feeding sign on flaxes there, most likely due to flax weevil. In Autumn 2013 consultant ecologist Geoff Walls, possibly escaping my snoring, made a night-time expedition and came back with the definitive photos of flax weevil. It’s nice to know they hung on during the rat years, and that they are now obviously abundant. We are gratified the island is suitable for macroinvertebrates also, and don’t plan on overlooking them. We are also on the lookout for ngaio weevils, which would be a find. Who knows what may have persisted?
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.
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.