Photo: Weltvogelpark Walsrode. Raising the tone: Stanley cranes (Grus paradisea) bring a touch of class to many bird gardens and zoos, such as Weltvogelpark Walsrode
Meet the leading South African supermodel: the Stanley (or blue) crane is arguably the most elegant of all the handsome crane species. Whether adorning a collection or sauntering in the wild, it never fails to draw appreciative looks from its human admirers, says Bill Naylor
LONG-NECKED, long-legged wading birds, cranes are considered the catwalk models among water birds. A number have plumage adornments and crests, and all are statuesque and elegant. Apart from specialist private collections, cranes are likely to be found in zoos and bird gardens, where they are well represented.
They have a long history in aviculture, and do well in captivity, being long-lived and easy to maintain. That’s as well, because most crane species are in decline and threatened. According to the First Breeding Records by Reuben Girling, published in the Avicultural Magazine, most of the 15 species of crane have been captive-bred. The established protocols for their maintenance and breeding are due to the success of the International Crane Foundation. Starting in 1971, it has become the headquarters of crane captive breeding and research. Anyone keeping cranes should acquire their crane husbandry manual (visit: www.savingcranes.org).
Bird of paradise
The blue crane (Grus paradisea), also known as the paradise crane but more commonly as the Stanley crane, is almost entirely light blue-grey. It lacks a crest and is the only crane with a completely feathered head, highlighting its expressive eyes and face. It appears to have a long full tail but, like all cranes, its real tail is short and hidden. The train of feathers that almost touch the ground are in fact its long flowing secondaries. The tips of these are black, the same as the primaries, which are hidden when grounded. Twelve crane species inhabit wetlands, while others like the Stanley crane are mostly found on dry grasslands, mainly in eastern South Africa, often away from water.
Most cranes gather in flocks of varying sizes outside of the breeding season. They move from one area to another, often travelling hundreds of miles, and also migrate long distances in flocks at high altitude. When breeding, they separate into isolated pairs.
The Stanley crane is more often seen in pairs soaring on thermals at a great height. At 117cm (46in) high, it is the second smallest crane after its close relative the demoiselle crane (G. virgo).
What a voice!
Stanley cranes are sexually mature at four years, but can take up to seven years to breed. All cranes are excitable. They chase each other and dance, which involves bowing and jumping, and excitedly picking up items like twigs in their beaks and throwing them, accompanied by their loud trumpeting calls. In captivity they will also call when other birds such as geese fly overhead calling. The power of their vocals is due to the extended windpipe (trachea), which enters the sternum. Crowned cranes have a shorter windpipe, so their voice are not as strong as that of other cranes. Stanleys pair for life, and the pair bond is maintained when they are part of a flock.
Cranes are often exhibited with waterfowl, such as geese, and will also harmoniously share an enclosure with pelicans, or even ostriches and rheas. But they are territorial. In an average sized enclosure they will not tolerate other individuals of their own species. They will also become aggressive and preoccupied with cranes housed in adjoining pens. For this reason they are usually screened from each other.
They defend themselves by kicking and stabbing with the beak and can be dangerous to zoo visitors and keepers, because without warning they can stab at the face. Keepers often wear face masks when catching them up and the birds then often have their head covered with a cloth bag to calm them down. In South Africa and elsewhere, wing-clipped Stanley cranes are not infrequently kept as pets or free-range, like peacocks. But as with all cranes, their tendency to peck at the face makes them dangerous to children.
Cranes do best in roof-netted enclosures. Fortunately, it’s illegal to pinion cranes in some European countries. Pinioned males often experience difficulty in mating, and wooden staircases located near the nest have been provided as an aid to coupling.
During a flightless period the primaries and secondaries are moulted simultaneously every two years. Wing-clipped birds should only have primary feathers and at most one or two secondaries on one wing clipped. The last three primaries should be left intact, because these cover and protect the delicate blood-filled quills when the bird is moulting. When clipping is undertaken, the date should be recorded and a close watch kept on birds because they can become airborne before the flight feathers are completely grown. In windy weather, aided by their wings, they can gain elevation and clipped and even pinioned birds can scale fences and escape.
Enclosures should always be grassed, since hard surfaces such as concrete can damage the cranes’ feet. Ideally, too, they should be planted with ornamental grasses, shrubs and trees for shade. A deep pond is needed for bathing. This type of enclosure will encourage invertebrates – an important part of a crane’s diet. All cranes vary their food according to the season. They eat a surprising amount of plants, including seed heads, acorns and the rhizomes, roots and tubers of marsh plants.
Wild Stanley cranes are considered beneficial by farmers because they eat a high proportion of locusts, plus all types of insects, frogs, fish and rodents. But like all cranes they can cause damage to wheat, corn and other crops. Some farmers target them even though they eat a great number of agricultural pests.
The International Crane Foundation recommends cranes should have 19 per cent protein as part of a maintenance diet, upping that to 21 per cent during the breeding season. The main part of the maintenance diet is a formulated crane pellet, seeds and grain supplemented with fish, raw meat, wholemeal bread, boiled egg, diced fruit, and insects such as crickets and locusts. Food is often provided in deep dishes placed on pedestals to deter wild birds from stealing it.
Nesting and incubation
Cranes nest usually on the ground. Crowned cranes, unlike others, can roost and nest in trees because their fourth rear toe is high and well developed. Some species build bulky nests, which are added to as they are reused.
Stanley cranes are often said to be unique in having a nest in dry areas with no material other than a few stones. That is not quite accurate. Some Stanley cranes build at the edge of the water or in long grass, and here their nests will be substantial. Those that choose to build on high ground often have just a bare nesting area surrounded with pebbles. Courtship involves duet calling and dancing, with both birds bowing and throwing their heads back. The female is ready to mate when she crouches down in front of the male.
The female and the larger male share incubation duties and sit the two buff- brown spotted eggs for 30 days. The long-legged youngsters – the larger individual always being dominant – are fast-growing and eat smaller items of the adult diet supplemented with chick crumbs. They acquire the feathers for flight at three months old.
Bill Naylor has enjoyed a 40-year career in ornithology and aviculture.
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