Once a common sight on European farmlands, the handsome great bustard is now one of the most endangered species in the world.
It is wintertime in Austria. Peering through his telescope, Rainer Raab scans the fields of Marchfeld, an agricultural area northeast of Vienna. He is estimating the number of great bustards that are wintering in this area. The shy birds are hard to detect amid the tall stands of rape, their main food source during the cold season.
After World War II, more than 700 members of this magnificent species lived in Austria. The population declined in the following decades and, despite conservation efforts that began in the 1960s, dwindled to 61 individuals in 1995. Efforts to reverse the trend are finally beginning to bear fruit, for the number of these birds in Austria has slowly climbed to almost 100.
Raab, a 33-year-old zoologist, works for a government-sponsored program to protect the great bustard. He persuades local residents to spare the bird’s breeding areas from intensive farming. The Austrian government subsidizes the cultivation of rape as part of the conservation effort. About 350 farmers currently participate in this program.
After a heavy snowfall, the fields need to be cleared with machines because the great bustard is unable to dig for food. Moreover, if the rape freezes and becomes spoiled, it loses its nutritional value and the birds may die of malnutrition. During severe winters, great bustards tend to migrate to better feeding territories dozens or even hundreds of miles away, and there is no guarantee of their return the following spring.
Raab is concerned that if the migratory birds stay away, their small population in Austria may decline further. He and his coworkers hope that this population can be kept intact by genetic exchanges with other members of the species in neighboring Hungary. Last winter, however, the population in Hungary suffered a loss of nearly 100 birds. Some of them were probably poached while wintering in warmer places such as Italy or the Balkans.
Meet the bird
The great bustard (Otis tarda) is the largest bird native to Europe and one of the heaviest birds capable of flight worldwide. The adult male can weigh up to 35 pounds, with a length of about four feet and a wingspan of about eight feet. It is boldly colored, with orange-brown feathers on its lower neck and a pattern of brown and black bands on its back and tail. Its head, upper neck, and underside are white. The female has a more subdued coloration and reaches only 13 pounds in weight.
Despite their size, these birds are excellent long-distance flyers. Those living in Russia migrate in winter to the Crimean Peninsula. Satellite observations have documented the birds crossing a distance of more than 600 miles within five days.
Great bustards generally inhabit open grasslands, steppes, and extensively cultivated areas. They feed mainly on plants, including agricultural crops like rape and alfalfa, but they also prey on insects such as grasshoppers and locusts and may even catch mice.
During the winter, small groups of great bustards join together to form larger groups, sometimes numbering more than 100 birds. These congregations dissolve at the onset of the mating season at the end of March and beginning of April.
Courtship is nothing short of spectacular. Several males form a group, displaying their plumage to nearby hens. The courting male produces a drumming sound, resembling “oh-oh-oh,” that can be heard from more than 100 yards away. In response, hens occasionally utter a soft “geek-geek-geek” sound.
Franz Josef Kovacs, an Austrian photographer who has spent much time watching the birds, describes the courtship display. “The males ruffle their feathers, throw their heads backward, raise their tails, and turn the white undersides of their wings outward. They seem to produce feathery balls that can be seen from far away, attracting the hens to the mating site. Most females seem to favor the same male, and interestingly, the female may take the initiative after she has made her choice. Once I watched a hen pecking a hesitant cock, trying to make him mate with her.”
During courtship, the male struts around the same place every day, ignoring obstacles in his path. If a hen shows interest, he pumps up the baggy skin on his large larynx and starts wobbling. Eventually, he lowers his head to the ground. When the hen comes close, he starts moving around her slowly, touching her gently with his wings. If the hen accepts him, she sits down. The mating lasts one to two minutes–an unusually long time for birds.
While great bustards are generally peaceful, the mating instinct may drive them to behave aggressively. They may peck each other, push with their breasts, or fiercely bite their rivals’ necks. “Once, as I watched two males fighting each other, four nearby hens felt so excited that they also started to fight among themselves,” smiles Kovacs. For the rest of the year, the males and females live in segregated groups, though in close proximity to each other.
After mating, the hen digs a simple hollow in the soil in which she lays two or three eggs, colored pale olive or brown with dark spots. She sits on the eggs for four weeks, but if disturbed by humans or animals, she immediately abandons her nest, never to return. Nest-robbing predators, such as the fox, contribute to a high loss of eggs. For this reason, Raab spends most of his spring and summer days on the farmlands, keeping walkers, joggers, and dogs away from the nesting sites.
For the first two weeks after hatching, the mother feeds her young with insects. She then teaches them how to find food and avoid being eaten by other animals. After five weeks, they are capable of flying but stay with their mother for several more months. The growing female reaches sexual maturity around the age of three or four, while the male takes five to six years or more before being able to compete for the hen’s attention.
The need for intense motherly care during the early stages is one reason why captive breeding has met with limited success. Captive-bred juveniles become used to human care and lack some important survival skills when released. Lately, however, some progress has been made with captive breeding in Germany and Ukraine.
Population growth and decline
Scientists believe that the great bustard originally populated the boreal steppes of the Eurasian continent. After the Ice Age (which ended about 10,000 years ago), the population expanded westward, following cultivation of the land. Feathers and bones of this species have been discovered in graves dating back to the Bronze Age, suggesting that the bird inhabited farmlands of that era.
The population growth reached its climax during the Middle Ages, when many of Europe’s primeval forests were turned into farmland. The open fields benefited the great bustard so greatly that it preferred them over its former habitat on the virgin steppes. The birds were a common sight throughout Europe until the nineteenth century. In some places, they were so numerous that they were considered pests.
When traditional agriculture was replaced by intensive farming, the great bustard lost much of its habitat and many sources of food. Today, it is among the 24 most endangered species in Europe. To provide the great bustard with maximum protection, its status is listed in the European Community Birds Directive, and the governments of about a dozen middle European nations have signed a special Memorandum of Understanding.
Spain has the largest population of great bustards: an estimated 23,000 individuals. This number has been held steady by maintaining large, nonintensive farmlands and well-managed protected areas with a prohibition on hunting. A recent analysis by scientists of the Institute of Zoo and Wildlife Research in Berlin shows that the Spanish population differs genetically from the birds in other countries. The second-largest population, roughly 7,200, occurs in Russia and Ukraine.
In Hungary, with the expansion of intensive farming, the number of great bustards dropped from 3,000 in the 1980s to about 1,100 at present. Ornithologist Attila Bankovics of the Hungarian Natural History Museum notes that as a result of management efforts at the Kiskunscg National Park, it is “the only area in Hungary where the population has not decreased but shows a growing trend.” Between 1975 and 2002, the number of these birds in the park increased from 140 to 440. Protective measures included feeding the birds during severe winters and keeping visitors and grazing cattle away from breeding sites.
Outside Europe, the great bustard can be found in Morocco, Turkey, Mongolia, and the steppes of Central Asia. Estimates of the worldwide population range from 38,000 to 42,000. In many places, however, the numbers have rapidly declined, and in some regions the species is on the brink of extinction.
In the wild, the great bustard’s life span may stretch to 20 years, but many birds die much younger. “Some juveniles are killed by harvesting machines, while most are killed by foxes and birds of prey. The birds also die in collisions with power lines. From November 2002 to June 2003, six birds were found dead below power lines,” says Raab, voicing his concerns. Nevertheless, he and his fellow conservationists throughout Europe are determined to win the battle for survival of this “flying heavyweight.”
Barbara Grabner, a journalist based in Vienna, works for the Austrian Union for Nature Conservation and the Donau-Auen National Park. She expresses her gratitude to Austrian zoologist Rainer Raab and Hungarian ornithologist Attila Bankovics for their expert advice and review of the manuscript.