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Every year the Christchurch City Council organises a spring celebration to mark the arrival of the first Godwit migrants. The Christchurch Cathedral bells ring for 30 minutes when the first birds are seen on the Avon-Heathcote Estuary.
The Bar-tailed Godwits (Limosa lapponica) each year fly 11,000km from Alaska to spend the southern summer on the Christchurch coastline.
Ranger Andrew Crossland keeps an eye open after mid-September for the arrival of the Bar-tailed Godwits from their non-stop journey over the Pacific Ocean.
The harbingers of spring mass for migration on the Alaskan coastline after finishing breeding further north in the Arctic tundra. Our knowledge of their movements is better than ever before as about 20 birds are fitted with satellite trackers prior to departure from New Zealand.
These Godwits are tracked as they returned to the breeding grounds via a route which takes them past New Guinea and the Phillippines to a half-way stop in the Yellow Sea of China and Korea. Then comes a second epic flight parallel to the Aleutian islands across the North Pacific and back to the north slope of Alaska.
Scientists report that the godwits make the longest non-stop flight of all birds – an amazing 11,000 kilometres from Alaska to New Zealand, in only five or six days.
"The Godwit breeding ground is tundra, moss and swampy tarn, where they feed on insects," Mr Crossland says. "After breeding, they move to the shorelines and estuaries along the Alaskan coast to build up for migration by feeding on shellfish and sea worms."
After spending the southern summer in New Zealand, resting and gaining weight, the Bar-tailed Godwits leave in March for the long flight back to the breeding grounds.
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Godwits on New Brighton beach
© Andrew Crossland
When it is time for the Godwits to migrate south, they wait for favourable wind systems and storm fronts that give them speed and carry them far out over the Pacific.
Observers report that when the birds finally reach New Zealand they are clearly starving and bedraggled, eating voraciously regardless of the stage of tide. They need to feed to replenish what they lost en route – about half their body weight. Three months later, in preparation for the northward return flight, they start to stock up on food, building up fat-deposits and doubling their body mass.
Arriving from late September, during the Southern Hemisphere spring, the majority of the 80,000–100,000 Godwits head for Kaipara and Manukau harbours, the Firth of Thames, Farewell Spit, andlarger estuaries like the Avon–Heathcote estuary near Christchurch. Roosting in large flocks they spread out to feed at lowtide, foraging over the mudflats and shoreline for molluscs, crabs, marine worms and aquatic insects, probing the mud with their long bills as the tide recedes.
These relatively large waders average 40 centimetres and 325 grams, the females heavier than males. Brown with a long bill and medium length legs, their front turns ruddy red when they are plump and ready for the return journey.
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