Friday, November 12, 2010

Greytown's birds - the Shining cuckoo

Here it is November already and I have yet to hear the shining cuckoo in Greytown. The Birding News Group reported a shining cuckoo in the Rimutaka Forest Park on September 21 and a friend reported them at the top of Wood Street in late October, which is about when I would have expected them here, as it has been late October in other years that I have first heard them. The extremely cold October weather may have deterred their moving south.
Talking to someone recently, they said they did not realise we had cuckoos here in New Zealand. Indeed, we have two, the shining and the long-tailed cuckoo, both migratory. The long-tailed cuckoo will only usually be seen outside the deep bush while it is in transit in the spring and autumn, when they very often are found dead after crashing into a window. (As I was writing this I had an email from soomeone living nearby in the Waiohine Gorge saying they had a long-tailed cuckoo crashed into the window!) But the shining cuckoo is everywhere, largely because its main dupe the grey warbler is very widespread.
Shining cuckoos are heard before they are seen. Their call starts like someone whistling for their dog and then tails off into a series of downward notes like a long sigh. Trying to follow the call to identify the bird can be a frustrating experience as it is very deceptive. The bird can be quite close without one knowing as the call starts off quietly as if a long way away, so they are difficult to actually sight.
However, I have been lucky in that they were want to frequent the kowhai trees in the garden on the farm where I used to live in the eastern Bay of Plenty and so I often watched them meticulously searching through the tree at my kitchen window for the larvae of the kowhai moth. Here in Greytown I have not seen them at all, just heard them.
The bird is a bit larger than a sparrow and is wonderfully marked with an iridescent greenish blue coat above a striped off-white body. Their diet consists almost entirely of insects and their larvae and includes the hairy caterpillar of the magpie moth which is avoided by all other birds.
There is probably no doubt that the scarcity of insects in the winter has been behind the evolutionary drive for the shining cuckoo to migrate. They leave around February or March and follow a route north which is not clear. On leaving their winter quarters many, if not most, birds, make their way down the eastern Australian coast before flying across the Tasman to New Zealand. Immature birds may travel the same route in reverse while adults may make a more direct flight of over 3000 km over the Pacific Ocean when trade winds could give some assistance. They have been recorded on Lord Howe and Norfolk Islands during the migration seasons.
Like other cuckoos, the shining cuckoo neither builds its nest nor rears its young. It leaves this job to the grey warbler who manages to rear one clutch of its own before the cuckoo arrives here around September from the Solomon Islands and the Bismarck Archipelago.
If the cuckoo’s migration path is a bit of a mystery, how it’s egg gets into the grey warbler’s nest is another. The grey warblers build a covered, hanging nest with a small circular entrance which is just too small for the cuckoo to enter without damaging the nest. However, in the September, 1991, Nortornis, the official publication of the New Zealand Ornithological Society, there is a photo of a cuckoo carrying an egg in its beak. In my view, this seems the most likely way in which the egg is placed in the warbler’s nest.
The birds that come to Greytown are those most likely born here. When one thinks of all the hazards between here and the islands, then it is not difficult to calculate that we could easily lose these birds locally. If just two or three pairs of birds come to Greytown, they have to breed successfully every year in order to make up for the losses incurred while migrating.
Climate change will also effect the future of these birds, but perhaps not negatively as a warmer climate may allow them to stay on through the winter rather than migrate.
Maori tradition believed the shining cuckoo wintered in Hawaiki, which indicates that they were well aware of the bird’s migratory habits. However, it was probably from observing the long tailed cuckoo, Koekoea, which winters chiefly in Fiji, Tonga, Samoa, Cook, Society and Tuamotu groups, which lead the voyaging ancestors of Maori to believe that there was land to the south.

Ko te uri au i te whenakonako
I te koekoea.
E riro nei ma te tataihore e whangai.

I am the offspring of the bronze cuckoo,
Of the long-tailed cuckoo,
Left here for the white-head to feed.

Maori and European tradition regarding cuckoos is not so different as is revealed by a song of Shakespeare’s: “The cuckoo then, on every tree, mocks married men; for thus sings he, cuckoo!”
Call of the Shining Cuckoo may be heard here:

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