great Indian bustard
great Indian bustard, (Ardeotis nigriceps), large bird of the bustard family (Otididae), one of the heaviest flying birds in the world. The great Indian bustard inhabits dry grasslands and scrublands on the Indian subcontinent; its largest populations are found in the Indian state of Rajasthan.
Physical features
Great Indian bustards are tall birds with long legs and a long neck; the tallest individuals may stand up to 1.2 metres (4 feet) tall. The sexes are roughly the same size, with the largest individuals weighing 15 kg (33 pounds). Males and females are distinguished by the colour of their feathers. Feathers on the top of the head are black in males, which also possess a whitish neck, breast, and underparts, along with brown wings highlighted by black and gray markings. Males also have a small, narrow band of black feathers across the breast. In contrast, females possess a smaller black crown on the top of the head, and the black breast band is either discontinuous or absent.
Predators and prey
Great Indian bustards are omnivores that feed opportunistically; that is, they feed on any palatable food in their immediate surroundings. They prey on various arthropods, worms, small mammals, and small reptiles. Insects such as locusts, crickets, and beetles make up the bulk of their diet during the summer monsoon, when rainfall peaks in India and the bird’s breeding season largely takes place. Seeds (including wheat [Triticum vulgare] and peanuts [groundnuts; Arachis hypogaea]), in contrast, make up the largest portions of the diet during the coldest and driest months of the year.
Adult great Indian bustards have few natural enemies, but they display considerable agitation around certain predatory birds, such as eagles and Egyptian vultures (Neophron percnopterus). The only animals that have been observed to attack them are gray wolves (Canis lupus). On the other hand, chicks may be preyed upon by felines, jackals, and feral dogs. Eggs are sometimes stolen from nests by foxes, mongooses, monitor lizards, and Egyptian vultures and other birds. The greatest threat to the eggs, however, comes from grazing cows that often trample them.
Reproduction
Although some of the reproductive behaviours of great Indian bustards are known, the finer details of nesting and mating, as well as migratory activities related to nesting and mating, are thought to vary greatly among populations and individuals. For example, they are capable of year-round breeding, but for most populations the breeding season lasts from March through September, which largely encapsulates the summer monsoon season. Likewise, while they do not return to the same nests year after year, typically creating new ones instead, they sometimes use nests made in previous years by other great Indian bustards. The nests themselves are simple and often are located in depressions made in the soil in low croplands and grasslands or are situated on rocky open ground.
Whether or not the species uses a specific mating strategy is unknown, but elements of both promiscuous (where members of both sexes mate with multiple partners) and polygynous (where males mate with multiple females) mating have been observed. It does not appear that the species forms pair bonds. Lekking, where males assemble at communal display sites to perform for and court females, occurs in some populations. However, in other instances, solitary males may attract females to their locations with loud calls that can be heard at least 0.5 km (0.3 mile) distant. The male’s visual display involves standing on open ground with the head and tail raised, its white feathers fluffed, and its gular sac (neck pouch) filled with air.
After breeding takes place, the male leaves, and the female becomes the exclusive caregiver for her young. Most females lay a single egg, but clutches of two eggs are not unknown. She incubates the egg for approximately one month before it hatches. Hatchlings are capable of feeding on their own after one week, and they become fully fledged when they are 30–35 days old. Most hatchlings fully emancipate themselves from their mothers at the beginning of the next breeding season. Females may breed as early as age two or three years, while males become sexually mature at age five or six.
Few discernible patterns of migration have been observed among great Indian bustards outside of the breeding season. Some may make short local migrations within a region, whereas others fly longer distances across the subcontinent.
Conservation status
In 1994 great Indian bustards were listed as an endangered species on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species. By 2011, however, the population decline was so severe that the IUCN reclassified the species as critically endangered. The most recent population estimate, which was conducted in 2008, reported that an estimated 50 to 250 mature birds remained; however, smaller regional surveys conducted since then noted that local populations have continued to decline. The largest concentration of great Indian bustards, perhaps 120 birds, occurs in the state of Rajasthan.
Habitat loss and degradation appear to be the primary causes of the decline. Ecologists have estimated that approximately 90 percent of the species’s natural geographic range, which once spanned the majority of northwestern and west-central India, has been lost, fragmented by road-building and mining activities and transformed by irrigation and mechanized farming. Many croplands that once produced sorghum and millet seeds, on which the great Indian bustard thrived, have become fields of sugarcane and cotton or grape orchards. Hunting and poaching have also contributed to the decrease in population. These activities, combined with the species’s low fecundity and the pressure of natural predators, have left the great Indian bustard in a precarious position.
In 2012 the Indian government launched Project Bustard, a national conservation program to protect the great Indian bustard along with the Bengal florican (Houbaropsis bengalensis), the lesser florican (Sypheotides indicus), and their habitats from further declines. The program was modeled after Project Tiger, a massive national effort initiated in the early 1970s to protect the tigers of India and their habitat.
John P. Rafferty