10 January 2018 | The Pūkorokoro Miranda Shorebird Center, Firth of Thames, North Island, New Zealand
Photo: There no longer is a bridge to the bird blind that sits on one shell ridge with a younger ridge beyond
After stopping briefly to wander through the annual, open-air Gold Rush Market on the main street of Thames, which still has a few old buildings remaining from the gold-rush period after 1867, we continued around the head of the shallow bay of the Firth of Thames. Now called by its Maori name, the Waihou River was named the River Thames by Captain Cook in 1769 when he thought that it resembled its namesake in England. Given how the lower reaches of the Thames might have looked in the mid-eighteenth century and how this New Zealand rift valley would have been full of podocarp forest and wetlands rather than the current farmland, this might not have been unreasonable but the similarity might be hard to find today.
On the west side of the Firth of Thames, we passed through the tiny hamlet of Miranda to reach the Pūkorokoro Miranda Shorebird Center (Pūkorokoro translates to windpipe or trachea but I am not sure of the significance of this part of the name). We were going to spend the night in the Sandpiper Suite so that, at our leisure, we could wander along reserve's trails and admire...well, shorebirds.
The Firth of Thames is listed as a wetland of international significance under the Ramsar Convention (named after the first convention held in 1971 at Ramsar, Iran). This is because it is part of the East Asian-Australasian Flyway (EAAF), which is a network of routes used by migratory birds in the Asia Pacific Region. The EAAF supports up to 7 million shorebirds, 5 million of which are migratory, and include species such as the red knot, sharp-tailed sandpiper, ruddy turnstone, red-necked stint, and bar-tailed godwit which spend the southern winter in arctic sites such as Siberia and Alaska. With many of these birds stopping during these amazing migrations northward and southward in the Yellow Sea, there are close ties between the Miranda Shorebird Center and similar wetland reserves in China and Korea.
The Center is inland of the coastal road but trails lead to the water's edge where there are blinds that overlook the shell ridge that becomes an isolated spit and the roost for many birds at high tide. The area is thought to be the best example of shell chenier plains in the world. A series of 13 cheniers, or shell ridges, have formed the 2-km wide plain on the west side of the Firth of Thames over the last 4,500 years. Each ridge is initially formed in shallow water parallel to the shore. Gradually the ridge is pushed landward by tidal and storm events. Eventually the ridge is raised above the tide with mangroves and saltmarsh colonizing the landward side of the ridge after sedimentation starts to fill and naturally build-up the plain. Near the water, it was not difficult to identify the sand and shell ridges that are separated by wetland that lie parallel to the shore but it would become harder to distinguish the older ridges further inland.
We had the strange experience of seeing that this process had been in action just a few day's previously. The storm that crossed the area on Friday night and Saturday morning had coincided with a "King" high tide (exceptionally high spring tide). With northerly winds that gusted up to 65 knots (120 km per hour) blowing directly into the Firth of Thames, considerable waves built-up. During the King high tide at 11am on Saturday, the waves overtopped the series of seaward shell banks and then the road. This was watched with horror by the Shorebird Center staff but luckily the Center buildings were sufficiently high off the ground to be spared from flooding...just.
The owners of many buildings in the nearby village of Kaiaua were not so fortunate and we were sad to see piles of mud-ruined furniture, bedding, and appliances that would need to be replaced in those of the flooded houses that could be made habitable again. The landward migration of the cheniers could be clearly seen where the road was close to the water. Although now swept clear, it was obvious where the roadway had been covered by the adjacent shell ridge that the waves and tide had pushed inland.
Sand and shells have been swept off the road near flooded houses in Kaiaua
Keith, who had worked at the Shorebird Center for 25 years, said that it was the worst conditions that he had seen there. The freshwater pond by the Center buildings that had been almost dry due to the preceding drought, had been flooded with saltwater, as had many pastures and fields of crops. The latter were obviously brown and lost and there would be quite a change in vegetation in the area because the saltwater had not drained or been diluted away immediately after the flooding.
Flooding debris along the fence-line and saltwater in the agricultural fields
The sanctuary trails were mostly closed because they were covered with a hazardous slimy mud but we were able to drive to the south entrance and walk to two blinds overlooking the freshly reshaped outer shell bank. The trail bridge to one blind had been swept away but the water had receded enough to allow us to walk across without getting too muddy.
Randall on the trail out to the blinds for bird-watching
There were two volunteers (one from the US and one from Wales) at the blinds who were helpful in identifying the birds and explaining how the birds may have been affected by the storm-event. Most species were not impacted in the long-term but some of the late-season nests and nestlings would have been lost.
We saw four species that were new to us: wrybill, bar-tailed godwit, banded dotterel, and sharp-tailed sandpiper. We were also shown where there were red knots but my views were not very clear so I did not count them. There were many bar-tailed godwits which are fairly large (40 cm or 16 inches long) wading birds and have long, slightly upturned bills that are pink and black. These were not particularly close but there were many of them and they were quite distinctive when seen through binoculars.
The species that I had most wanted to see, was smaller but also closer and also in good numbers. These were the native migrants (nesting elsewhere in New Zealand) wrybills.
Sadly my bird photos did not come out clearly but I did not realize this until later. Apparently my new polarizing filter does not work with the lens zoomed out (causing a double image) so that was really annoying. I had experienced no such problems with my previous filter so this new one must be a cheap brand.
Thanks to my cheaply made new polarizing filter, my impressionist view of the brown bar-tailed godwits in front of the newest shell ridge
Consequently, it was just as well that I had bought a tee-shirt at the Center's gift-shop to get a clear picture that shows that the wrybills have a bill with its tip bent to the right (always the right). This is not very obvious unless seen from the front so it took a while for me to recognize this on the birds seen through my binoculars. Wrybills are the only birds in the world with such a laterally asymmetrical bill (only the lower mandible of the Asian openbill stork is sometimes twisted to the right and the upper and lower mandibles of crossbills bend in opposite directions). The wrybills bills are thought to be adapted for stirring-up invertebrates from under stones in the shingle riverbeds where they breed in the South Island.
Alison in her tee-shirt showing the right-curving bill of the wrybill
Other birds that we saw were the internal migrant South Island pied oystercatchers and several resident species such as black-backed gulls, variable oystercatchers, pied stilts, New Zealand dotterel, and red-billed and black-billed gulls. Despite the photography disaster, our stay at the Miranda Shorebird Center was very satisfying.
Hannes and Sabine from SV Cayenne (we first met in Hawai'i)
The following morning (January 10th), we drove north on the coastal road to Clevedon and then up to Half Moon Bay Marina. Here we tracked-down SV Cayenne with Hannes and Sabine aboard whom we had not seen for a year. They were supposed to be circumnavigating both islands of New Zealand but their engine had finally packed-up in the Hauraki Gulf and they have been waiting in Half Moon Bay for several weeks for a new engine which was due to arrive any day. The storm had been nasty for them, lifting the dock that they were tied alongside onto the top of the supporting posts for a short while. Luckily Cayenne was undamaged although the dock needed some major repairs.
Cayenne (at right) on the dock that was lifted onto the grey post in the storm (Rangitoto Island on the horizon)
From there we returned to Whangarei, only stopping briefly north of Auckland to buy two new dinghy paddles (replacing the heavy temporary one that Randall had fabricated in Tonga after we lost one at Minerva Reef). We were very relieved to find all well with Tregoning despite gusts of close to 40 knots when the storm passed through. It had been a whirlwind tour of the North Island south of Auckland but we felt that we had been incredibly lucky with the wonderful things that we saw, the great roads that we had chosen to follow, and the weather. Thank you, Vandy and Eric, for entrusting your car, Baxter, to us for such great adventures.