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.