Birds Of Sandy Island: 2. The Sandy Island Giant Pigeon

THE SANDY ISLAND GIANT PIGEON (Neoraphus immobilis)

The Giant Pigeon is arguably the most unique and bizarre inhabitant of Sandy Island. Considering that flightlessness and gigantism in pigeons has only occurred in a very few other places - the Mascarenes, St. Helena, and Fiji - the Sandy Island species offers a great comparison with the others. This species is usually slightly smaller than the Mauritius Dodo but still an enormous pigeon at around 26 to 29 inches in length. Like the Dodo, the Sandy Island Giant Pigeon has very small wings. Its legs, however, are rather shorter and slenderer than those of other giant flightless pigeons. The neck and bill are also not quite as long and thick as the Dodo’s; the gape is just as wide. The head is surmounted by a brushy tuft of filoplumes like an egret or a silkie rooster. The tail is short and tapered, not plumous as in the Dodo. This species’ general coloration is gray, like the Dodo; similarly, the face is unfeathered and dark grayish. Rather unusually for a pigeon, the eyes are quite large.

The most remarkable characteristic of the Sandy Island Giant Pigeon is related to its seasonal fat cycle. This species times its breeding with the fruiting of the wattle palm, and as the palm’s fruits fall they become the pigeon’s only diet. The pigeons gorge on the fatty palm fruits, which makes them the fattest of all wild birds - and at that time they are not only flightless, but walkless. The Giant Pigeon is the only species of bird that is (at least temporarily) incapable of locomotion both on wing and on foot.  A fully fattened Giant Pigeon moves by rolling on the ground, usually sideways but occasionally end over end. The motion is similar to the trajectory of a thrown balloon full of yogurt, or a closed plastic garbage bag full of milk on a sloping Slip ’n’ Slide. For obvious reasons, Giant Pigeons mate before they get quite to that stage; only once the eggs are laid do they become truly walkless. The nest is a mere scrape in the ground, if that - the island’s lack of terrestrial predators means that Giant Pigeons can just lay their two white eggs (rarely three) on the ground. These eggs are too large and thick-shelled for a Robber Starling to crack, though Great-billed Crakes occasionally crake them; it should also be noted that the Giant Pigeon’s (and Dwarf Du’s) breeding season is in the northern hemisphere summer, when migratory Bristle-thighed Curlews, also notorious egg thieves, are elsewhere. 

The Giant Pigeons have a unique incubation system brought about by their walklessness. Their circadian rhythms during the fat season are essentially arbitrary; they eat until they tire of eating, regardless of the time of day. When they can no longer eat they roll to the nearest available nest and sleep on the eggs. (This is surely why the eggshells are so thick!) The nests are close enough together that this takes little effort; when a pigeon wakes it simply rolls off the nest in search of more fruit. The bird’s large eyes are a testament to its occasional nocturnal wakings. Whenever one wakes, it gives the eggs a turn so that they will be properly incubated by the next sleeper. With this system of random incubation (termed by some wags “incubus incubation” but really a modified creche system), there is no guarantee that a Giant Pigeon will ever incubate the eggs that will hatch its own offspring. Once the chicks hatch, the adults continue the same behavior, with some unique twists. The chemical digestive process that in other pigeons creates “pigeon milk” has been repurposed for a different way of feeding the young. It is not entirely understood, but the ultimate effect is that it causes wattle palm fruits to be indigestible, and the adults must regurgitate them - into the chicks’ mouths. This is also how the adults lose weight. By the time the young leave the nest (quite early for a pigeon), the wattle palms have stopped fruiting and the adults begin to regain their walking abilities.

At the start of the nonbreeding season, Giant Pigeons frequent beaches, where they take advantage of the newly arrived Blue Noddy breeding colonies, eating eggs when they can and sometimes even noddy chicks. The pigeons kill noddy chicks with a technique that is unknown elsewhere in the bird world: despite their lesser weight than during the breeding season, the pigeons are still hefty enough to catch downy young noddies by lying down on them and squashing them. This is a decidedly rare occurrence. When there are no more noddy eggs, the pigeons do not risk squashing a lot of noddy chicks. Instead, they go after robber crabs, attempting to crack the shells of small individuals and scavenging crab carcasses when they find them. Success in this endeavor is limited; there are usually enough fallen fruits and seeds from other trees to tide the pigeons over until the wattle palms fruit again.

The Sandy Island Giant Pigeon is not a noisy species. In the nonbreeding season it occasionally utters pig-like grunts and squeals. The same sounds are adapted into a chattery call frequently uttered when rolling to and from the nest - the Warburton expedition thought that if they were ever slaughtered by colonizing humans, the chattering and squealing of the dying birds would resemble the group laughter in the Beatles’ “Revolution 9”, reversed. Breeding males call with a low, blown-bottle-like “brooowlt-brooowlt-brooowlt-brooowlt”.

Birds of Sandy Island (Ornithologia Sandiniensis): 1. The Dwarf Du

The Turnstone is back with a new series of posts concerning speculative biology. Lately I've been fascinated by this genre of nature writing, so I decided to share a project that I've been working on for a while. Sandy Island is a "phantom" island in the southwest Pacific, west of New Caledonia. Despite being shown on maps for about a century, it never existed. Reading about this, I wondered what birds would live on Sandy Island if it was real. I came up with a list of 49 species that might breed on this island, most of which are real birds that would conceivably be there given the ecology and biogeography of the surrounding region. I made up ten of these species, which would live on Sandy Island and nowhere else. Here on The Turnstone I will post descriptions of each of these imagined birds. For reference in this project, I used two of my favorite books: Birds of Melanesia, by Guy Dutson, and Extinct Birds, by Julian Hume and Michael Walters.

A note on the writing style: Birds Of Sandy Island is written in a pretentious style with a lot of self-mockery. There are quite a few internal references that the reader is not always expected to "get". Also, extinct birds are frequently mentioned as if they are still with us. With that out of the way...

THE DWARF DU (Microsylviornis xenicus)

As many Pacific islands are inhabited by scrubfowl (Megapodius), so Sandy Island has a representative of this broad group. Sandy Island’s scrubfowl, however, is much more than a mere Megapodius; it is a member of that highly evolved offshoot of the tribe that contains Sylviornis, the giant Du of Grande Terre. With the discovery of Sandy Island’s dwarf Du, it is now obvious that size does not define Du-ality. The Dwarf Du is only about eight inches long, less than an eighth the size of Sylviornis. Its flightlessness makes it the only non-flying bird of its size that isn’t a crake or a grebe. Roughly scrubfowl-shaped but with a proportionally shorter, thicker neck, the Dwarf Du is feathered all over with fluffy rusty-blackish plumage, texturally similar to that of the Mauritius Red Rail. Like its giant cousin it has a thick rounded bill and a bony frontal casque; its eyes are surrounded with a patch of bare skin that can be distended in the male’s courtship display. In fact Wrye, the naturalist of the Warburton expedition that discovered Sandy Island, first considered classifying the breeding male as a separate species: the Wattle-eyed Du. Once he finally saw one at the point of beginning the courtship display, Wrye famously remarked, “Oh, Wattle-eyed Du now!”

Megapodes famously use heat to incubate their eggs, and the Dwarf Du is no exception. Like most megapodes, it buries its eggs in a mound of dead leaves. Though not quite the massive constructions of the Grande Terre Du, famously once believed to have been human burial mounds, formidable heaps are created by the Sandy Island species. Still, they are the smallest of all megapode mounds; in some places they appear as mere pimples—which would make adaptive sense if Sandy Island was volcanic (so they would get the rest of their heat from geothermal activity). Unfortunately, it isn’t. The Dwarf Du doesn’t seem to know that, though. Its small head, while not exceptionally small, is mostly jaw. More on that later.

Anyway, Dwarf Du differ from other megapodes in their habit of laying eggs in well-defined clutches within the mounds. Four is an average clutch size; the mound is only finished once the eggs are all laid, to ensure that the chicks hatch and emerge from the nest together. The interim period between egg laying and mound finishing, referred to by the islanders as “the bornge”, would be much more dangerous if Sandy Island had monitor lizards or snakes. As it is, it is still dangerous; eggs are predated by Robber Starlings and the occasional Great-billed Crake. Giant Pigeons do not take eggs, as the Dwarf Du coordinate their breeding with that of the pigeons so that there will be no Du eggs during the pigeons’ oophagous nonbreeding season.

Like other megapodes, the Dwarf Du is omnivorous. Insects and a variety of seeds are easily crushed in its proportionally heavy beak, but its preferred food is the seeds inside the fruits of the glasper vine. This strangler fig-like plant, which engulfs shrubs and small trees with a seeming lack of self-awareness, has very hard seeds which the Du’s jaws are adapted to crack. The Dwarf Du has a decidedly prehistoric facial appearance, with the large jaws taking up most of its flat head. Its call is usually a chicken-like “kek-kuk”, becoming an upslurred “krawk” when excited. The displaying male walks with a high step, shaking his head from side to side before stopping, head held high, and uttering an accelerating series of accented “keeark” notes. Young Dwarf Du begin displaying shortly after emerging from the mound.

New 'monics

As birders know, transliterating bird calls is never accurate or precise. I have read some debates about whether or not it is practical to do so (to form mnemonics for identification), but I generally think it works most of the time. Some people believe the main problem with transliterations is that bird calls often sound like different syllables to different people, and so appear written differently in each book (field guide). I do not consider this a problem, because in my field experience I have imagined words words for bird calls I've heard that are different from what I've seen written in the field guides. Some examples (click on the name of the bird for a link to the recording):

Least Tern

This recording is a little confused because there are a lot of them calling at once, but at certain points you can hear them go "Reykjavik! Reykjavik! Reykjavik!" It's too bad there are no least terns in Iceland.

Carolina Wren

This is a very variable song but I've found this particular variation to be the most common. It is usually transliterated as "teakettle teakettle teakettle" but I hear "tweet eater tweet eater tweet eater". Does this make more sense or less sense with the advent of Twitter?

Yellow Warbler

Most field guides only transliterate the "type A" song of the yellow warbler, usually as "sweet sweet sweet sugary sweet!", which is accurate. However, I have often found the "type B" song, which is easily confused with those of some other warblers, to be just as common. Because the similar song of the chestnut-sided warbler used to be written "see see see Ms. Beecher", I put in a name for this yellow warbler song as well. I hear it as "see see see Chester Biddlechick".

Blackburnian Warbler

I haven't seen this written out as words, but I hear "chewy chewy chewy chewy cheeeeese!!" (The first time on this recording is at 0:12)

Scarlet Tanager

This one really ruffles my feathers. In every field guide I've seen, this has been written as a hard or hoarse "chip-burr" or something like that - in a couple of cases "chip-churr" and in one instance even described as a dry rattle! The Audubon Society field guide comes closer by using the adjective "twanging", but still it transliterates it as "chip-burr". Nowhere does anyone come close to the metallic ringing quality I hear in this sound. I have always heard it as "tick-bang". The field guide descriptions actually led me astray, and before I saw a scarlet tanager making this sound, I couldn't identify the sound. Go out to your nearest woods or large park (if you're in eastern North America) and try to find this sound. It's a relatively common bird and they're nesting now. Tell me it isn't "tick-bang"!

-Elijah

Birds of paradise- final update: penguins and knees

About a week ago I finally got to see some of the "lost" bird-of-paradise specimens at the American Museum of Natural History. Unfortunately I was not allowed to take pictures, but I did make some decisions for myself about whether or not certain forms are hybrids. For example, the specimen of Wilhelmina's Bird of Paradise, which in the book was considered a probable hybrid between the so-called Magnificent and Superb birds of paradise, looked to me very much like a separate species. If it were somehow proven that it was, I think instead of Wilhelmina's it should have a superlative name (taking the example of the Superb and Magnificent), such as the Marvelous, Spectacular or Awesome Bird of Paradise. *

What would a female Superb, accustomed to this...

see in this Magnificent, anyway?

On a related topic, there is another Renaissance Dutch painting reproduced in the Fuller/Attenborough book that is just as thought-provoking as the scene with the owl that I posted about earlier. This is a painting of the Garden of Eden by Jan Brueghel the Elder. (Unfortunately I cannot find a large enough/high resolution enough photo of it online- look it up.) In addition to Greater Birds of Paradise and plenty of other accurately depicted animals, it contains a penguin that appears to have external knees. At the turn of the 17th century, when this was painted, penguins were very poorly known to Western man; it is understandable that certain details of their appearance would be likewise unclear. However, since no living birds have external knees (except for certain domestic breeds of pigeons), some people, such as Brueghel, could have even been uncertain that penguins were birds at all. Judging from the knees that Brueghel gave his penguin, it is likely he thought its closest relative was the frog.

Even as late as 1930 some people thought penguins were plants.

This book sets things straight about penguin knees, by the way.

-Elijah

*I would have put in Wonderful but that name is used for another of the "lost" ones, which, by the way, is almost definitely a hybrid. I can confirm that.

How does this turnstone feel?

Here is a photo that was very recently posted on the Internet Bird Collection. It was taken last summer on an island off the coast of Germany and shows a phalarope apparently picking something off the feathers of a turnstone (the bird that this blog is named for). Though someone who is unfamiliar with these birds could think this is an example of a symbiotic relationship like the one between bee-eaters and bustards in Ethiopia, it is in fact rare and exceptional. Phalaropes usually attract their prey by spinning. Perhaps there was a particularly tasty fly about to bite the turnstone. The phalarope, which (given the time of year) was stopping here on its spring migration to the Arctic, could have been both hungry after a long flight and too tired to do that spinning dance for its food. It wouldn't have cared that the fly it saw was only sitting there because it was busy biting a bird. It is impossible to tell from this photo what exactly is going on, but since the caption says the phalarope is apparently picking insects off, it can be assumed that it isn't simply chasing or harassing the turnstone, which would be much more likely. At any rate, what the phalarope is most decidedly NOT doing is picking bugs off out of empathy for the turnstone.
I'd say the turnstone must be uncomfortable about feeling an unexpected beak on its back.

-Elijah

P. S. There could be another reason that the phalarope is not doing phalaropey things. Unlike most birds, female phalaropes are larger and more dominant and territorial than males. They leave the males to deal with the eggs and chicks. Maybe this male phalarope was simply too nervous to think straight.

Birds of paradise update, plus how to turn hostility toward owls into art

Though I still haven't been shown the bird specimen collection at the American Museum of Natural History since the last post, I did in fact get to meet Errol Fuller, if only for a brief moment. About a month ago I played an "opening set", also at the Museum of Natural History, for a lecture by the author and artist Katrina van Grouw about her book The Unfeathered Bird, which is really cool and I'll probably write a post about it soon. This lecture happened to coincide with a lecture in the museum's other theater by David Attenborough, which was about Drawn from Paradise, a new book he co-wrote with Errol Fuller about the history of the birds of paradise in Western/European culture. Attenborough and Fuller were signing copies of this book after the lecture, so after I saw Katrina van Grouw's presentation I got in line to meet them. I didn't have their book yet, so I had them sign my sheet music.

Recently I got Drawn from Paradise, which is at least as awesome as The Lost Birds of Paradise which my last post was about. I haven't read all of it yet, but so far I haven't found any reference to the other book I wrote about last time, the one by Tim Laman and Ed Scholes (it's not in the index). However, I did notice a few observations about bird of paradise behavior that I thought may have been taken from Laman and Scholes' book. For example, the chapter about the 12-wired Bird of Paradise mentions that the male's special "wire" feathers are used to tickle the female's face, a fact I seem to remember reading that Laman and Scholes had discovered- I'll have to double check. *

(Tim Laman's photo of 12-wired tickling.)

One really cool thing I found in Drawn from Paradise relates to a painting, reproduced in the book, which is part of a series by the 17th-century Dutch artist Frans Snyders which depict a large group of birds of different species singing together, with an owl conducting them from a score. Attenborough and Fuller include this painting because there is a Greater Bird of Paradise in it, but their caption also mentions that the inspiration for these paintings may have been the observation of mixed flocks of songbirds converging around a roosting owl and scolding it. A taxidermied version of this behavior, which is known as mobbing, can be seen in the Japanese scene in the Museum of Natural History's hall of Birds of the World. I also wrote a tune that represents mobbing; it is the third movement of Bird Lives. The bass represents the owl.

More updates to come.

-Elijah

*This makes me think of the lonely male 12-wired Bird of Paradise that lived in the Bronx Zoo for much of my life- it needed someone to tickle so it was sent to another zoo in Germany that had a female.

Birds of paradise, mastery and mystery

Birds of paradise (which, to clarify for non-bird people, are any of about 40 species found in New Guinea and adjacent islands) are among the subjects, in any writing, that induce the most superlatives. Their collective name is one; so are some of the names of the individual species, such as Magnificent Bird of Paradise. This is due not only to their beautifully colored and textured plumage but also their diversity (it is hard to tell that some of them are related to some others), their apparent intelligence and in some cases the inaccessibility of their habitat, in dense rainforest or on remote mountains. It is all well and good to use superlatives about them, but once you’ve got those out of the way, how do you continue? There have been quite a lot of books about birds of paradise, and the ones I’ve read deal with this issue in very different ways.

Greater Bird of Paradise

Tim Laman and Ed Scholes’ book The Birds of Paradise (2012) is the result of eight years of expeditions to observe and document as many aspects of bird-of-paradise life as possible. It is definitely an impressive book, with lots of photos that definitely invite superlatives: many are very close-up and show the birds in action, eating or interacting with each other, often in their courtship displays. Laman and Scholes write about new discoveries regarding the birds’ behavior, as well as possible explanations for how all these diverse species and their lavish appearances could have evolved. This book frequently plunges into the facts after the superlatives are over. It is very precise; Laman and Scholes seem to be on their way toward mastery of their subject.
Laman and Scholes’ book contains many quotations from other bird-of-paradise books. One book that is notably not quoted from is The Lost Birds of Paradise by Errol Fuller (1995). This is a very different book on a slightly different subject: the birds of paradise that were collected and prepared as stuffed specimens, mostly from the 1890s to the 1920s, that are now in museums and do not fit into any of the known species. To me this book is at least, and almost certainly more, interesting than the other one. It is very much a history and extremely well researched; much of it is a skeptical response to the writings of a German biologist in the 1930s who claimed that all of these specimens that do not fit the known species are in fact hybrids. Though Fuller agrees for a few of the specimens, he makes the case for many others not being knowable for certain. Possibly they are separate species that are very rare or extinct; perhaps they are hybrids between other species than was originally assumed. This feeling of mystery serves to make the book particularly awesome, as do old pictures that provide historical context (such as an illustrated poem from some time in the late 19th century criticizing the wanton use of feathers {such as bird-of-paradise feathers} in hats, titled “A Killing Hat”- who knew the use of “killing” as a superlative was that old?). More importantly, Fuller’s book never stops with the superlatives. They don’t get in the way, but they give the book a sense of wonder that I feel is much more overt than in Laman and Scholes’ work, though it is far from lacking in the latter. It is this kind of wonder, I think, that put all the superlatives in the birds’ names in the first place.

-Elijah

P. S. I am trying to set up a opportunity to go behind the scenes at the American Museum of Natural History and see the bird specimen collection, which has many of the “lost” birds of paradise. Expect an update!

One of the "lost" ones. I might get to see these exact feathers!