Intrepid operations manager and volunteer Grant Davey donned his wet weather gear on Saturday to report on the state of the river birds and today (Sunday) he took another look. Here is his report.
This was the biggest November flood since records began at the gorge in 1972. Peak flow at the gorge was 246 cumecs at 3pm on Saturday. It hit as nesting season was in full swing.
Colonies of black-fronted terns had started nesting, black-billed gulls had settled in with a few nests established and wrybill and banded dotterel chicks were appearing. But many birds still sitting on nests had no chance when the flood came through.
So, nests and chicks have been lost but we know many birds will bounce back and nest again, and some will go elsewhere.
It is likely to be a while before water levels go down enough to do a bird count.
Other damage is loss of traps – probably about 20 were washed away.
Black-fronted terns (tarapiroe)
Overall, probably all the tern nests have gone – we had mapped 41 which I think were still occupied, two of these had hatched small chicks. My estimate is there were around 36 nests still to be found at the known colony sites. So we probably had more nesting pairs than last year. We knew of 15 nests which had been predated (rats, stoat, harriers, hedgehogs) or abandoned because of predators.
In the Railway area where there was a large tern colony there are very few terns around today, and the colony downstream from Smarts appears to have lost all nests.
Black-billed gulls (tarapuka)
The places where the gulls were have been covered in water, but there are still a couple of hundred of them in the general area. Hopefully they will settle down and nest. At the estuary the BBG colony is still there. I think there are a couple of hundred more gulls nearby. Also, several hundred gulls in a paddock not far from the beach settlement. Probably Waimak refugees.
We knew of only one pair of wrybill still on a nest which has probably gone. Some of the wrybill chicks may have survived.
Banded dotterel (pohowera)
There would be probably tens of BD on nests along the river, and a lot of chicks. Probably all the nests will have gone, some of the chicks will probably be OK.
The Marchmont – Smarts island, which we saved by working with a gravel extractor and ECan, was still sticking up nicely yesterday afternoon. But it did go underwater as peak flow came through. It’s possible it will be a site for new nests.
The below shows nest destructive floods during the nesting season – above 100 cumecs at the gorge seems to be bad and 50 cumecs will get some nests. We might have to think about making islands higher. And doing more with gravel extractors to make deeper channels around them.