Considering Cranes

According to Pat Sharkey, Curator of the Upper Zoo and avid ornithologist, the largest percentage of threatened bird species falls within the order Gruiformes, the marsh-adapted birds. If animals must be kept so that we may learn, educate, and conserve - and clearly they must - Roger Williams Park Zoo is doing its share with the Gruiformes, housing three of its prototypical specimens, our wonderful cranes. As to the fourth objective of the zoo, to astonish, one can hardly deny that that's been met when gazing upon one of these graceful creatures.

The evolutionary and fossil history of the cranes and their relatives is still surprisingly unsettled, in spite of a rather large number of fossil forms. It's commonly agreed, however, that the birds arose in the Cenozoic period, about 60 million years ago. All of the cranes' incarnations, the ones surviving today and a phyletic line that some believe may have gone extinct, evolved perhaps from what is now the rail. Still the cranes evolved further along a separate course and are in fact now more closely related to trumpeters and limpkins. There are 14 species of crane in four genera. Balearica pavonia (the crowned crane) consists of four subspecies: the Sudan, East African, South African, and the West African, of which we have two, a male and female. The shorter bill, which swells at the tip, and the tufts of feathers on the crown distinguish this Genus. Aside from the wattled crane, the crowns appear to be the only species with chin wattles. The latter also have pronounced fleshy white cheek patches with varying degrees of red depending on the subspecies. Interestingly, pavonina comes from the Latin 'pavo', a peacock, and as it's the only crane with the tuft, it's easy to understand this moniker.

The African Crowned Cranes' migratory routes appear local, due perhaps to their respective territories, which are relatively close to one another, and a relative shortage of large wetland options at greater distances. During non-breeding seasons, however, the birds do flock to more favorable locations away from nesting sites. But the breeding patterns of the crowned cranes is a bit tricky. Generally they breed during the rainy season, but in wetter areas of Africa they breed when it's a relative dry season.

The species of Grus are often without feathers on their crowns and upper heads.Our sandhills are Grus. Like the crowned, there are subspecies of the sandhills, and as the crowned exist only in Africa, the sandhills exist only in North America, except when the lesser sandhill subspecies migrates to extreme northeastern Siberia to breed each summer. The zoo has three Florida Sandhills currently, Grus canadensis pratensis. Hogan, born last spring, will be removed and transferred shortly, if not by the time you read this. Florida sandhills do not really migrate, and with a new breeding season approaching, he is being pecked off by his parents Frazier and Lillith. You may see him in with the pronghorns for now.

Of the Sarus Crane there are two subspecies, Grus sharpei (the Burmese version) and Grus antigone (the Indian version). We house a pair of the antigones, two girls, Claudia and Cindy. These two subspecies had even more extensive ranges than they do now and antigone in fact represents longevity in some Japanese art, where it does not really reside today. Japan in fact has its own Japanese crane.

Cranes live quite a long time, easily to 50 years. There are few if any seasonal movements of the Indian sarus. Only in extreme drought do the birds attempt traversing the mountainous region they live in. The relatively heavy birds are however quite capable of long migrations and have recently set themselves up in Australia, some 3,000 miles away.

Cranes appear to eat both vegetation and animal matter. They are fond of both large and small insects, worms, blue crabs, and especially corn in North America. While flock sizes are generally (at least with the lesser sandhills) less than 100 pair, the basic on-ground unit seems to be three, namely the family unit. They are very regular in their locale movements and daily endeavors, leaving the roosts just after sunrise and returning at dusk, to and from their foraging sites, generally within a mile.

Clutches are generally small, about an average of two to three eggs. Both parents of many species share incubation, the female usually through the night, the male taking longer shifts during the day, when they alternate around six times. Many cranes have impressively long tracheal anatomies that invade the sternum, loop and sit in its keel. The longer, the deeper the possible range of a "Whoop!" As you might guess, the whooping crane, also North American, has a relatively long trachea.

Cranes have held the fascination of humans since human existence. They are found in many myths and fables, not to mention some of the classics. A major character from one fable was the Pygmies' queen Gerania. She was turned into a crane by two other deities because she taught people to ignore other gods and worship her. The same story appears in the Iliad of Homer. The superfamily Geranoidea is the lineage mentioned earlier that ultimately died out. Cranes appear in art to a great extent. It is also said that the mythic hero Palamedes from the Trojan Wars invented many Greek letters by watching the convolutions of flying cranes. But a hugely unfortunate fascination with cranes came with the milliner industry, where their feathers were used for hats. This devastated a few species until they became protected.

And now, as mentioned earlier, the largest threat is less innocuous: the slow but steady loss of habitat. President Bush relaxed restrictions on wetland development. Already, huge expanses of greater sandhill breeding grounds in the northern central states have gone away. The birds have traveled further into the northern grounds of the Canadian subspecies, Grus canadensis rowani. Still it's possible to view the beautiful birds in the diminishing Platte River basin in Nebraska each year as they head north. If you're really lucky you may even see a pair of whooping cranes.

So contact your state and federal representatives and tell them you want wetlands protected. They are Rhode Island's most threatened ecosystem. And don't forget, take your hats off to cranes.

Tom Paulhus
Docent Class of '02