New Zealand's connection to the arctic: waders of Te Waihora | Lake Ellesmere, Summer 2022-23
Summer time is a peak period for wading birds around New Zealand. This is due to the diversity of species that arrive after migrating from the northern hemisphere. Other species that breed locally also come to the lake shores to feed, which creates a unique composition of species from New Zealand and abroad. Most of the "summer migrants" come from the Siberian and Alaskan arctic zone, where they breed. For a long time, the breeding biology of many of these species was unknown,
as they simply left in the Autumn with no breeding, nests or eggs to be found. This mystery was expressed by many cultures, including Māori , with the proverb -
Ko wai ka kite I te hua o te kuaka?
Who has ever held the egg of the kuaka?
The kuaka, or Bar-tailed godwit (Limosa lapponica baurei) is the most common arctic wader in Aotearoa / New Zealand, and so was most notable as a mystery animal.
It is thought that their consistent migration may have even assisted in discovering Aotearoa, as the Māori ancestors observed these birds flying South, and concluded there must be a landing place of some sort in the South Pacific.
Other than the kuaka, there are many other arctic wading birds that reach New Zealand - many of which are seldom observed on iNaturalist. Wading birds (or Shorebirds) are species part of the order Charadriiformes. They are characterized by their feeding habits on shore or wetland areas, where they forage in mud for micro-insects, crustaceans and worms. For many people, these Arctic waders can be easily overlooked, as they are often smaller birds, sometimes with drab plumage, are found in inaccessible locations, and come to New Zealand in very small numbers (often declining numbers too). However, these birds are significant as they make up the avian biodiversity of places such as Te Waihora | Lake Ellesmere. It is a delicate relationship between two environments in the world, as Lake Ellesmere supports these special birds, and it allows them to flourish when they return to their breeding grounds: the arctic tundra. So, the protection of both places is incredibly important for the continuity of these amazing species. It is a fascinating ecological relationship between two opposite sides of the world.
Lake Ellesmere or Te Waihora, is a large coastal lake in Canterbury, New Zealand, south of Christchurch city. It is one of the largest lakes in New Zealand, however it is very shallow. Although the lake is considerably polluted with eutrophication, it supports huge numbers of birds, including waterfowl, shags, grebes, herons, gulls, terns, spoonbills and waders (https://tewaihora.org/about-the-lake/ecology/birdlife/#:~:text=In%202021%20more%20than%2049%2C944,by%20the%20Waihora%20Ellesmere%20Trust.). Over the 2022-23 (from November to April) summer, I visited various sections of Lake Ellesmere 13 times, in my own time and to contribute to surveys of the birdlife. Over these outings, I recorded a total of 14 wader species, and one hybrid taxon.
Locals (breeding in New Zealand)
Pied Stilt | Poaka (Himantopus leucocephalus)
This is the most numerous wader on the Lake, with large groups found wading for food along many of the coasts. I personally counted over 600 at one point, at the eastern mudflats. Pied stilts come to Lake Ellesmere to feed, but breed in adjacent wetlands and inland areas during the winter and spring.
They are native to New Zealand, arriving here from Australia in the 1800s, perhaps correlating with the decline of the endemic Black stilt.
Pied x Black Stilt Hybrid (Himantopus leucocephalus × novaezelandiae)
This is a bird I have seen many times, in small numbers, amongst Pied stilt flocks.
Hybrids are common between these two species, and are a conservation problem for maintaining the genetic purity of the Black stilt - I am unsure if the hybrids are sterile or not. These birds appear as an intermediate color morph between the two species. Pure Black stilts also visit the lake, but are rare.
South Island Pied Oystercatcher | Tōrea (Haematopus finschi)
From my personal observations, this species appears to be more common on local estuaries such as the Avon-Heathcote or Ashley. I have seen odd one at Lake Ellesmere, with larger flocks feeding in nearby paddocks during the winter.
Spur-winged plover (Vanellus miles novaehollandiae)
I observed flocks of these common lapwings along the lakes' edge. They are a common bird, often seen in pairs in wetland areas or paddocks. They only recently started breeding in NZ (first in 1932), coming from Australia, perhaps because the New Zealand environment was altered for western agriculture.
These are notoriously noisy birds and often skittish at the sight of people.
Banded dotterel | Pohowera (Charadrius bicinctus bicinctus)
A common wader to the estuary - large flocks of these birds were present over summer, with presumably most breeding in the local vicinity (e.g. Kaitorete Spit). Some Banded dotterels also breed in the South Island high-country, however apparently fly 1600km west to Australia in the off-season. By mid-summer, banded dotterels have finished having chicks, and are often out of breeding plumage. I observed hundreds of these birds feeding in the mudflats, and also roosting amongst the lakeside vegetation. Smaller numbers are sometimes seen at other local estuaries, however the species is generally declining due to nest predation.
Wrybill | Ngutu pare (Anarhynchus frontalis)
This bird is also fairly common on Lake Ellesmere, although not as common as the Banded dotterel. Up to 60 birds were seen in Nov-Dec along the nor-eastern mudflats, where they are observed to feed along all other species. These are one of the few endemic waders in New Zealand, and are placed in their own genus.
Arctic breeders and the East Asian-Australasian Flyway
The species listed below mostly breed in the arctic coastal tundras of Siberia and Alaska, during the northern summer. Many of these species also use a "flyway", known as the East Asian-Australasian Flyway. This is a strategic route taken by these migrating birds which allows for adequate resting and feeding areas while these birds migrate. Again, this is a delicate chain of environments which require global environmental conservation.
Bar-tailed godwit | kuaka (Limosa lapponica baurei)
Although this is the most common arctic migrant that comes to New Zealand (~75,000), I didn't observe many at all at Lake Ellesmere. There is a chance more of these birds live in the southern perimeter of the lake (which I did not visit)
These birds are much more common on surrounding estuaries such as Avon-Heathcote, and around March-April they migrate to far-eastern Siberia and Alaska for breeding.
Red knot | Huahou (Calidris canutus, subspecies rogersi and piersmai)
These are the second most common arctic migrant to New Zealand (~30,000), although large numbers of these birds are not found at Lake Ellesmere, but rather other locations such as North Island estuaries and Farewell spit. As I spent most of my time at Greenpark Sands, I only occasionally saw these birds, as they would seemingly fly in from elsewhere, feed, and often fly away again. They might also be primarily feeding on the southern coast although it is hard to know considering how large the lake is. The most I saw was a group of 9 in late April, which may be quite late for them to still be in New Zealand. This was evident with some of the birds with a rich red breeding plumage. Apparently two subspecies come to New Zealand, both of which breed in the Siberian arctic.
Ruddy turnstone (Arenaria interpres)
These were reliably seen waders on the Sands of Greenpark, with their unusual stubby form and blotchy colors. Up to 36 were seen here in December. Around a few thousand come to New Zealand each summer, most of which likely leave in April-May. Their breeding grounds are again Siberia, possibly in the same places as the Red knot. Although they look generally unequipped for long-distance flying, they breed extremely north, but can also be found extremely south in summer, as I have observed this species on the Subantarctic Enderby Island.
Red-necked stint (Calidris ruficollis)
These tiny waders are rather common on the Lake shore - particularly at Greenpark Sands. 45 of these birds were seen here in January, although there is probably more that live on the lake. The estimated population that comes to New Zealand is only 50-200, so the lake is very important for this species!
Although they are relatively numerous, they can be very difficult to spot, and often I came across them by realizing I was walking into a flock! However they are relatively wary of people (like most waders at Lake Ellesmere for some reason) and will fly away if disturbed. Most of these birds breed in North-west Siberia.
Pectoral sandpiper (Calidris melanotos)
The first of the two main "sandpipers" which regularly come to Lake Ellesmere. Only a handful of Pectoral sandpipers come to New Zealand every summer, with a decent percentage of these being at Lake Ellesmere. When they arrive, like all arctic waders, they are scrawny and tired after the long migration.
But noticeably, they become rather plump before they leave again, almost resembling a Weka (Gallirallus australis) in shape.
Pacific golden plover | Kuriri (Pluvialis fulva)
A pretty plover that migrates from the arctic. We counted a huge number of these birds a at Greenpark Sands, of at least 67 on Boxing day. Interestingly, they are quite afraid of people on Lake Ellesmere, but I have heard they are completely fearless in other countries. They are also known to feed on the paddocks surrounding Lake Ellesmere, however this behaviors has not been observed for a number of years.
Sharp-tailed sandpiper | Kohutapu (Calidris acuminata)
The second of the two main "sandpipers", and the more common species in New Zealand. Again, inhabits the same habitat of the Pectoral sandpipers, and I occasionally saw them together.
Long-toed stint (Calidris subminuta)
This was the rarest wading bird to be observed on Lake Ellesmere this summer, with it being the second bird to ever be recorded in New Zealand. It was discovered by the Canterbury birder Fraser Gurney right before Christmas. I was lucky to see it a few times. Interestingly, the last one seen was also at Greenpark Sands 20 years earlier! Essentially, it resembled a Red-necked stint in shape, but had the plumage of a Sharp-tailed sandpiper. It stuck around for about a month.
Marsh sandpiper (Tringa stagnatilis)
A single bird made Lake Ellesmere home for a couple months this summer. This species is another vagrant wader to New Zealand with only a few records per year. It is not actually a sandpiper, but part of the genus Tringa, and so more closely related to the "Tattlers". It was quite wary of people and tended to feed with the larger Pied stilts.
Greater sand plover (Charadrius leschenaultii leschenaultii)
This is not a bird I personally observed at Lake Ellesmere this summer but one that was seen a couple times by others. It is a rarer vagrant to New Zealand, with only a couple records a year. They resemble a banded dotterel slightly, but have distinct structural differences. Interestingly, they are not arctic, instead breeding in China and Mongolia.
The importance of the Greenpark Sands Conservation Area
Most of the birds listed above where observed on the Greenparks Sands, which is protected by the Department of Conservation as a conservation area. This is extremely important as this space is one of the few places for birds such as the Wrybill and Banded dotterel to feed in such large numbers. The quantity and presumably variety of food also allows for a high diversity of wading species to visit these shores. Additionally, the plant communities of Greenpark Sands are quite unique and are worth protecting. Other valuable areas of Lake Ellesmere for waders include areas such as Kaitorete Spit, especially the tip.
