Let's not forget weweia

Our quiet little endemic grebe didn’t get a look in during Bird of the Century, but it’s still a winner for Ann Graeme.

⏎Any dinkum Kiwi will tell you that our Australian cousins are just show ponies. This was highlighted by last year’s Bird of the Century winner pūteketeke, the crested grebe, a native selfintroduced bird from Australia. Our endemic grebe, weweia, the dabchick, didn’t get a mention during the competition, much less worldwide attention, so here is their story to redress the balance. 

I’m observing a family of weweia, and they are fun to watch. The bird will be feeding, swimming in spurts, and snatching morsels from the water surface when it will suddenly vanish before your eyes! By squeezing its feathers against its body, it can decompress like a submarine. Then, propelled by its strong lobed feet, it can swim a long way underwater (up to 4m deep), hunting fish and invertebrates, before restoring its buoyancy and popping to the surface, far from the spot you were watching.

They used to be present in the lakes of the lower South Island but declined rapidly in the 19th century, and the last breeding pair disappeared in 1940. Today’s weweia dabchicks have their stronghold in the lakes of the North Island’s volcanic plateau, while the Australasian crested grebes live in the glacial lakes of the South Island. Smaller than ducks and with a longer neck and bright yellow eyes, weweia are specialised waterbirds. They live around the margins of lakes and ponds, and rarely go on land. They are not built for walking but are superbly designed for swimming and diving. 

Dabchicks are devoted parents. The pair I was watching had a chick nestled on its parent’s back and peering out between its wings. The other parent was diving, surfacing with a wiggling fish, and presenting it to its mate, who would turn and feed it to the chick. A few days later, the stripey chick was no longer being piggybacked. It was floating by itself while its parents dived and brought it food. The chick still wanted a ride, and, again and again, it tried to climb on board a parent. But the adults would have none of it and would tip the chick off. It was time to grow up. 

Australasian coot feeding chick. Bryce McQuillan

My weweia pair had a territory in an inlet in Lake Rotoiti. A pair of Australasian coots lived there too, and they had four chicks. Compared to weweia chicks, coot chicks are ugly. A newly hatched coot chick has a naked scarlet head and a fringe of orange fuzz around its beak, like a baby who needs a bib. The chicks bob on the water, squawking raucously, and their parents forage and dive to bring them food. 

The self-introduced coots are relative newcomers to New Zealand. Coots have a lot in common with weweia. They share the same inshore waters and both need calm, sheltered margins to anchor their big untidy nests. Coots are aggressive birds and twice as heavy as weweia. Might the newcomers out-compete and drive away the smaller endemic bird? 

This does not seem to be happening. Perhaps the difference in food preferences is sufficient to minimise competition. Weweia catches small fish, koura, and invertebrates like mayfly larvae, while the coot mainly plucks water weeds and sometimes grazes ashore. 

Not only are weweia and coots co-existing but decades of bird counts show that both populations are increasing. The current dabchick population of about 2000 has led to their status being raised from Threatened to Nationally Increasing. But the birds still face many threats. Norway rats can swim to their floating nests and eat the eggs. A rat control programme around the shores of Lake Tarawera was followed by a surge in weweia numbers. 

Last summer, Forest & Bird initiated a pest control project around the shores of Lake Rotoiti with the Lake Rotoiti Scenic Reserve Board, the Bay of Plenty Regional Council, and DOC. This should benefit weweia as well as possumravaged pōhutukawa and the freshwater mussels, kākahi, another favourite food of diving rats. 

Weweia are disturbed by passing boats and jet skis, and their floating nests can be swamped by the wake, yet otherwise the birds seem to co-exist with people. They live in greater numbers around boat sheds and jetties than elsewhere, although this may simply be because both people and birds like sheltered waters. 

Whatever the reasons for their success, the population of this charming endemic waterbird is increasing. Presently on the Rotorua lakes, there are about 1000 birds, swimming and diving and pattering across the water in their elegant courtship dance. And even better news, weweia are appearing in ponds and dams beyond their range in Te Ika-a-Māui North Island and as far south as Lake Forsyth in Canterbury, returning to Te Waipounamu South Island where they became extinct last century.

WEWEIA SPA HANGOUT

Sulphur Bay in Lake Rotorua is a hostile landscape. Clouds of steam waft across murky water, fringed by layers of sinter rock with cavities where hot water gurgles and spurts. Signs warn of the danger of straying from the path. Yet this is a favourite place for a host of waterbirds, and weweia dabchicks flock there in autumn. They are probably young birds, the chicks of the summer, grown up and sped on their way by their parents, who stay put on their lakeside patch. Flocking at Sulphur Bay offers a young weweia an opportunity to warm its feet (though the acidity of the water may damage its webs), feed on the wriggly midge larvae that thrive in the warm water, and meet potential mates.

Sulphur Bay, Rotorua. Image Andy king50, CC BY-SA 3.0, via Wikimedia Commons

Local volunteers started carrying out weweia dabchick surveys of 18 Rotorua lakes in 1985, and they have been carried out every five years since. Volunteers, DOC, and Fish and Game work together in boats to count and map weweia and all other waterbirds over a few days in late January. This is a fine example of citizen science and collaboration. The data collected provides a wealth of information, and, while presently it shows an encouraging trend in weweia numbers, it would also alert us should the population decline.