Survey of the lower part of the Okuku River: November 2019
The Okuku is an NW to SE running tributary of the Ashley, joining the latter about 22km inland from the coast.
An attempt was made, with Jean Jack of Environment Canterbury, to survey the Grey junction to the junction with the Ashley on 20/10/19, but water levels were too high. On 11/11/19 flow at Fox Creek was only 1.5 cumecs, making river crossings easy.
The survey was done from just below the Grey River bridge on Loburn Whiterock Road to the mouth of the Okuku. Thus the first interval, 8-9 on the below table, was a little longer than a kilometre.
Observations on the survey:
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The river has a fairway of up to about 200m width usually with 1 – 2 active channels. A fairly recent sizeable flood seems to have cleared most of the fairway weeds, but some are regrowing.
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There were 4 gravel operations seen, 2 large and 2 small. No extraction was currently being done at any of these.
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The gravel extraction areas are a definite locus for bird activity and breeding – particularly banded dotterel and pied stilts. Shallow ponds were present at all sites, stilts were seen feeding in these. Extraction areas, shown in yellow in the below map, are approximate only.
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There wasn’t evidence of much 4wd activity along most of the riverbed, except for downstream of the Birch Hill bridge. This seems to be a major 4wd access to the Ashley River.
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A group of horseriders were seen along the berm of the Ashley just downstream from the Okuku junction, they seemed to be heading out onto a bare gravel island where stilts could be seen.
About 20 cattle were roaming along the eastern berm, and crossing the river to some extent, west of Harpers Road.
Bird observations (numbers tabulated below)
Banded dotterel: only seen at and near the gravel extraction area in the Grey River. There were 4 pairs here with 1 almost fledgling chick seen. This is a similar number to that seen on 20 October, the fact that the birds remained there perhaps shows that breeding was successful.
Pied stilt: these were seen at or near all the gravel extraction areas. A total of 20 were seen, with 8 each at the two larger operation areas. One nest was found close to the old extraction area in the Grey and elsewhere the birds’ behaviour indicated nesting.
Black-fronted tern: a total of 12 were seen hawking along the river, sitings near the extraction areas were probably coincidental. The most were seen, 4, just above the Ashley confluence.
SIPO: one was seen at the extraction area north of the Birch Hill Road bridge. This almost certainly had a nest or chicks.
Other: these consisted of typical river birds, including white-faced herons, mallard ducks, Canada geese and little shags. They were distributed along most of the river.
