The Unburnt Egg Page 3
Reaching the island aboard SS Clansman, he was put ashore on one of the ship's boats. “The Capt. kindly helped me to fit out properly for my stay of one week alone.” The island, he reported, “was little more than a large rock (2 or 3 acres) with one peak and the greater part was covered with a low scrubby bush. On going ashore my attention was first attracted by the great number of green leaves on the ground. Underneath the bushes the ground was quite bare of grass and full of burrows of a species of Puffin.” These were probably flesh-footed shearwaters, Puffinus carneipes, which still breed today on the island.
“I first cleared away some vines and pitched my tent, which had to be done over some of the birds' burrows. As the sun neared the horizon Puffins approached from seawards and circled widely about the island, some collecting in rafts on the surface of the water. Just at dusk they came closer in and commenced diving into the bushes, which at once explained how the leaves had been knocked off.”
After dark, Adams took a lantern and a bag in search of tuatara, which stood still in the lamplight and were easily seized by the back of the neck. The commotion of the shearwaters calling and crashing about in the vegetation was, he wrote, a “strong contrast with the quiet condition during the day when a casual observer would think there were no birds to be found there at all”.
The week alone passed pleasantly enough. The weather was fine and Adams found the birds and tuatara “sufficient company to keep me from getting lonesome”. The shearwater eggs he found in the birds' burrows proved “very fine eating”.
On March 20, 1885, Cheeseman had received a telegram from a Dunedin taxidermist, William Smyth, offering a live king penguin from Macquarie Island, south-west of New Zealand. This arrived ten days later on SS Wairarapa. Smyth had put the penguin in a padlocked box and arranged for the ship's butcher to feed it en route for a consideration of five shillings.
Cheeseman was instructed to feed the penguin small fish and raw lean meat. “It has no bad nature,” Smyth observed. “If it snaps at one's finger it means nothing; it will not injure anyone's finger and will soon know and follow whoever feeds it.”
King penguins, Aptenodytes patagonicus, stand almost a metre tall and are second in size among living penguins only to the closely related emperor penguin. They are roughly circumpolar in distribution, breeding north of the pack ice on Antarctic and subantarctic islands. Macquarie Island has more than 70,000 nesting pairs.
With the penguin at the museum, Adams noted: “It is very amusing and took some fish which I bought for it tonight.” An art school was run at the museum, making use of exhibits such as the plaster copies of classical statues, so naturally “the young ladies of the drawing class came down in a body to see the penguin”. In Auckland there was no zoo where people could see live animals, and the many visitors who saw the penguin at the museum were “very much amused by its movements. ... It devours fish greedily and always seems to be hungry.”
Adams took the penguin to the studio of Josiah Martin, one of Auckland's leading photographers, so images could be made by the “instantaneous method”—a way of capturing movement using flashes of short duration. Then on April 9 there was a peremptory diary entry: “This evening I chloroformed the penguin.” Next day he started to prepare from it both a skin and a skeleton.
Many of the specimens that Charles Adams prepared during his two years at Auckland Museum were immediately put on display to educate and delight the public. A few remain on display 120 years later. An articulated skeleton of a king penguin is probably Adams' unfortunate bird: registration details show it was received in 1885 from Smyth and had come from Macquarie Island.
The study-skins prepared by Charles Adams have been noted and measured over the decades by a host of visiting scientists and students collecting data for research projects. This is the legacy of the quiet diligent man from Illinois who crossed half the globe to provide much needed taxidermy services to a small but growing colonial museum.
Secrets of the shining cuckoo
On a hot sunny day in November 1978 I was lucky in my field observations. As I walked through the dry kānuka forest at Kōwhai Bush near Kaikoura (in the north-east corner of the South Island of New Zealand), the air seemed to hum with the thrill of summer. Above the din of the cicadas I heard the distinctive whistling call of a shining cuckoo and went in pursuit.
Parasitic cuckoos have simple calls, most likely because their vocalisations need to be largely innate: while many young birds learn refinements of their calls from their biological parents during their period of dependency, this cannot be so in those cuckoos where the female lays her eggs in the nests of another species and plays no further part in raising the young. However, although the shining cuckoo's loud, clear call may be simple, something about it makes the position of the calling bird hard for the human ear to locate. The first iterations of the repetitive call may seem quite far away, but then the call seems to get louder and closer and the bird may even turn out to be perched nearby.
The shining cuckoo weighs around twenty-three grams— about three-quarters the weight of a house sparrow—and the sexes are alike in plumage. The bird belongs to a group known as the glossy cuckoos for their iridescent plumage. The dozen or so species in this group are the smallest members of the cuckoo family and inhabit wide areas of sub-Saharan Africa, Asia, New Guinea and Australasia.
Shining cuckoos are very hard to see in trees or scrub, despite—or perhaps because of—their striking appearance. The plumage of the upper parts is dark lustrous green, shot with copper or purple according to the angle of light. The under parts have bold dark green stripes running from side to side on a white background. The bird that seems so gaudy in the hand is remarkably cryptic perched still on a branch. Eileen Duggan captured this in her 1929 poem The Pipiwharauroa (Shining Cuckoo):
And I burnt my eyes with gazing.
Still I see the poplars shiver,
Still I hear the little runnels down the folded gully falling,
But I never saw the bird!
I persevered that day at Kōwhai Bush and eventually found two shining cuckoos. It is reward enough to watch such transient and secretive birds, but to cap it off I saw a red colour band on one of the birds' legs. Parasitic cuckoos tend to have short legs that are tucked well in when they perch. The feathering extends much further along the leg than in songbirds, so it is difficult to see the legs clearly to check for bands.
I lost sight of the cuckoos that day, but ten days later I found them in the same patch of bush. After half an hour of careful stalking I approached to five metres away—closer than my binoculars would focus—and there was no doubt that one cuckoo had a metal band on its left leg and a red plastic band on its right. This was B-40201, a cuckoo I had banded as a nestling exactly two years before at a grey warbler's nest a kilometre away. In my three summers of studying shining cuckoos at Kōwhai Bush I had been able to band only eleven nestlings from the small number of parasitised warbler nests I had under observation. I had banded no adults, but not for lack of trying to capture them by mist netting. I had given each nestling a unique combination of one numbered metal ring and up to two plastic colour bands. A numbered ring serves as an indelible marker should a bird be re-caught alive or found dead; the colour bands allow individual birds to be recognised at a distance from the exact combination on the bird's legs.
This young cuckoo had no doubt departed New Zealand at least once on its autumn migration north to the tropics, and had now returned to its hatching place attempting to breed. In the last sixty years only around 120 shining cuckoos have been banded in New Zealand, so this recovery record—with the suggestion of homing to a natal area—was important data.
Almost exactly 200 years before my fortunate field observation of a marked cuckoo at Kaikoura, and in the same month, others had been excited by the bird. The first shining cuckoo known to science was shot in November 1773 from aboard HMS Resolution at Queen Charlotte Sound, just 150 kilometres north of Kaikoura, during Captain James Cook's second voyage of discovery. From among the day's haul, perhaps the father and son painters Johann and Georg Forster found the tiny bird a particularly exotic and amazing subject, given its shining colours and bold pattern.
Back in Britain, the author and naturalist John Latham used the Forsters' painting and accompanying notes to list the species as “shining cuckoo” in his A General Synopsis of Birds, the part in question published in 1782. However, it was not properly named, consistent with today's rules of zoological nomenclature, as Cuculus lucidus until 1788, in a publication by a German naturalist, Johann Gmelin. Hence the bird's full zoological name today is Chrysococcyx lucidus (Gmelin, 1788). The brackets around the naming authority signify that it is now in a different genus from that in which it was originally placed. Things in zoological nomenclature often change and, to make the shining cuckoo's naming even more complicated, the Asian and Australo-Papuan glossy cuckoos are sometimes put in Chalcites, leaving Chrysococcyx for the African representatives.
Three of the shining cuckoo's habits are especially remarkable. One is its brood-parasitic breeding. Parasitic cuckoos lay their small eggs individually in the nests of foster parents smaller than themselves. The cuckoo egg hatches quickly and the cuckoo chick grows rapidly, pushing any eggs or other nestlings out of the nest. Being larger than the foster parents' own chicks it needs to be reared alone so it can monopolise all the food they supply.
Another notable feature is the shining cuckoo's diet. Among the insects it eats are many that other birds find distasteful. I studied the stomach contents of a sample of twenty shining cuckoos from the South Island that had died accidentally. Half the stomachs contained caterpillars— up to sixty per stomach—and a third of these belonged to the magpie moth, whose caterpillars are covered in sharp defensive hairs. Clusters of the caterpillars' spines in regular rows had pierced the soft gizzard lining, in much the same way the bristles of a brush are inserted. It's possible the cuckoo sloughs off the gizzard lining, complete with caterpillar hairs, and coughs it up. More than half the cuckoo stomachs held beetles—up to fifty-five per stomach. Nearly ninety percent of them were ladybirds. These insects discharge a poisonous fluid when molested and their colour is supposed to warn off birds from eating them.
A third wonder is the shining cuckoo's migration. Over the years I helped to work out the details of this by studying specimens in natural history museums. Shining cuckoos breed on mainland New Zealand and the Chatham Islands, where they parasitise the grey warbler and Chatham Island warbler respectively. The same species of cuckoo also breeds in south-west and south-east Australia. There it is called the shining bronze cuckoo and parasitises various birds that are close relatives of New Zealand warblers and, like them, build covered pear-shaped nests suspended in the foliage of trees and bushes. Shining cuckoos also breed in New Caledonia, Vanuatu and Rennell and Bellona Islands at the southern end of the Solomon Islands chain, and in all these places the host is—or is assumed to be—a local warbler with a covered nest. The populations breeding on these tropical islands are non-migratory.
Shining cuckoos that breed in the temperate latitudes of Australia and New Zealand are absent there in winter. It's thought they migrate north to spend the season in the tropics, the band of territory that runs from the islands of eastern Indonesia through New Guinea to the Solomon Islands. A study by the great German-American bird curator Ernst Mayr, published in 1932 and using specimens newly collected by the Whitney South Sea Expedition, showed that birds belonging to the New Zealand subspecies—with wide bills on average—seem to go east of New Guinea to the Solomon Islands. Since an article by New Zealand biologist Barry Fell in 1947, it is commonly assumed that shining cuckoos migrate directly between New Zealand and their wintering grounds, with the only possible landfalls en route at Norfolk and Lord Howe Islands. This constitutes a transoceanic return journey of 6,000 kilometres.
The Whitney South Sea Expedition was a venture of the American Museum of Natural History in New York and sponsored by wealthy philanthropists Harry Payne Whitney and Gertrude Vanderbilt Whitney. From around 1920 to 1932 a sailing boat systematically travelled to a myriad of islands across the south-west Pacific, collecting birds at each location. Subsequent study and comparison of the specimens back at the museum graphically showed that many types of birds had spread widely in the region, and on separate islands they had formed populations that differed in outward appearance. The island populations, although they clearly had a common ancestor, were now isolated from each other and were diverging in form and structure and evolving into separate species. This wealth of new data helped to refine the twentieth-century reinterpretation of the mechanics of evolution.
When the Whitney expedition visited Western Samoa in 1924, New Zealand was the colonial power. A condition of the collecting permit was that a representative selection of prepared and labelled study-skins of Samoan birds be returned to New Zealand authorities. Several of these important and historic Whitney specimens—mostly collected and prepared by Rollo Beck, a notable American taxidermist—are held in the bird collection at Auckland Museum. Natural history collections may grow and diversify in random opportunistic ways like this, as well as through systematic, focussed collecting.
But I am straying from the shining cuckoo's story. The Australian subspecies, which is characterised by birds with narrower bills on average than the New Zealand birds, seems to winter in New Guinea and the Lesser Sunda Islands at the eastern end of the Indonesian archipelago, and crosses continental Australia to get there. Although the technology is improving, shining cuckoos are still too small to carry satellite-tracking transmitters. None of the shining cuckoos banded in New Zealand have been recovered overseas, so we lack precise details of the migratory journeys. Instead we rely on bill widths to deduce that Australian and New Zealand birds have separate tropical distributions, paralleling their separate east-west breeding grounds.
To retest this assumption about separate migrations I undertook to examine study-skins of shining cuckoos held at natural history museums around the world. In any scientific study you need to set your protocols. For New Zealand and eastern Australia I confined my attention to the fresher and more reliable specimens that had been collected after 1944. For Western Australia and the tropics, samples were small so I used specimens of any vintage, the oldest of which was collected in 1868. I used only adult specimens so the bills would be fully developed, and rejected any birds with damaged bills.
In Brisbane, where I was employed at the start of the project, I examined and measured the shining cuckoos in the Queensland Museum, and the curator of birds kindly arranged to borrow specimens from museums in Perth, Hobart, Launceston and Port Moresby so I could see them too. Around this time I travelled to Melbourne, Sydney and Canberra for other reasons and was able to visit the museums there to measure their shining cuckoos. A holiday trip to London and Paris had me studying more cuckoos, and after later returning to New Zealand to live I gradually ticked off the birds held at the museums in Auckland, Wellington, Christchurch and Dunedin. Meanwhile, two helpful curators at museums in New York and Leiden sent me measurements they had made of the shining cuckoos in their own collections.
My main interest was in the width of each bird's bill, measured to the nearest tenth of a millimetre just in front of the nostrils. This varied from 4.1 to 6.1 millimetres. I compiled a set of data based on some 480 cuckoo specimens, with each measurement linked to the bird's place and month of capture. My graphs of the frequency with which specimens had been collected in different months and in different regions reconfirmed earlier assumptions that the Australian and New Zealand shining cuckoos inhabited the temperate and tropical zones at complementary times.
The bill-width measurements supported previous notions of the migratory destinations. The average was 5.2 millimetres in the Bismarck Archipelago (New Britain, New Ireland, et cetera), 5.3 in the Solomons and 5.4 in New Zealand, suggesting the same population was involved in migrations between these destinations. Likewise, mean bill widths of 4.5 millimetres in the Lesser Sundas, 4.4 in New Guinea, 4.5 in Western Australia and 4.8 in Tasmania suggested a separate north-south interchange of birds between those areas.
But I found that something strange was happening in eastern Australia. All cuckoos from Tasmania and Victoria were narrow-billed, as expected, but I discovered a large proportion of wide-billed birds among the narrow-billed ones collected in New South Wales and Queensland. When I looked at seasonality, by plotting bill width against month of collection, the penny dropped: wide-billed birds were present in New South Wales and Queensland only during the months of migration.
The data seem to confirm the proposition, first suggested by Ernst Mayr in 1932, that some, perhaps all, of the New Zealand cuckoos migrate via eastern Australia. This extends the return journey of New Zealand birds to Melanesia to about 12,000 kilometres but involves shorter distances across water—just over 2,000 kilometres between New Zealand and Australia, and just under 2,000 between Australia and the Solomons region. Of course it also allows the tiny cuckoos to rest and feed as they move up and down the Australian coastal plain.
It was sobering to think of the effort that had gone into the sample of 480 shining cuckoo study-skins to which I had access. Some of these birds would have been shot during expeditions to what were then remote locations and under trying conditions. Others would have crashed against windows, or been brought in by the cat, and the bodies carefully retrieved and taken to local museums by thoughtful citizens. Each bird would then have had to be skinned and stuffed by a preparator, a complex and exacting task. Each labelled specimen then had to be stored in a museum, and cared for during handling by researchers, building renovations, relocations of collections and even (in some cases) war. But in the end, the careful work of perhaps a hundred collectors, taxidermists and curators operating at a hundred locations during a hundred years had given me a representative sample of shining cuckoo study-skins. From these I was able to tease out a few of the bird's secrets, all to satisfy human curiosity and our burning desire to understand the natural world.