What is a Great Bustard?

COMMON NAME: Great Bustard

Bustard is derived from the Latin avis tarda, meaning slow bird.

SCIENTIFIC NAME: Otis Tarda

Otis

Otis is thought to come from the old Greek word for ear, as in an ear of wheat or barley which resembles the whiskers that the male Great Bustards grow each spring.

Tarda

Tarda, is Latin for “slow” or “deliberate”, which is thought to describe the walking style of the species.

COLLECTIVE NOUN: Drove

A group of Great Bustards is known as a drove. This could contain from 20-40 birds.

Taxonomy

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Gruiformes
• Family: Otitidae
• Genus: Otis
• Species: Otis tarda

Huge, heavily built and robust, but stately in appearance, adult male bustards can be identified by their bulging neck, heavy chest and characteristically cocked tail.

Their shape is similar to a large goose, but the bustard is much larger with considerably longer legs and a straighter neck.

Males develop a band of russet coloured feathers on their lower neck and breast, which becomes wider and brighter as they get older. They grow large impressive bold white moustache whiskers (20cm long) and the colours on their back and the tail become more vivid.

The female’s plumage is much more cryptic than males.

As a species their weight is on average 3-18kg. The average mature male can range in weight from 5.8 to 18kg, with the maximum recorded at 21kg. Females are up to a third smaller, ranging in weight from 3.5 to 5kg.

Great bustards have the largest sexual dimorphism in the bird world.

The males are much bigger: sometimes up to 5 times the weight of females and as much as 50% bigger in size.

Their average species standing height is about 75 -115cm. The male standing height is between 90–115 cm. A female’s standing height is 75-85cm.

As a species they have a 2.1–2.7m wingspan on average. The male wingspan is 210-250cm. The female wingspan is 170-190cm.

Bustards have special tridactyl feet. They have only three toes, which all face forward and lack an opposable hind toe (hallux). This means they can run very fast, but cannot perch on anything, so they are a ground-dwelling bird.

Great Bustards mostly inhabit open grassland, although they can be found on undisturbed cultivation. Traditionally birds of expansive grass plains, they have adapted well to arable farming in some European countries. Arable fields bearing crops such as oil seed rape and lucerne now appear to be more attractive than natural steppe, although farmland areas with high agricultural disturbance near human settlements are often avoided.

According to the IUCN Red List, the world’s Great Bustard population is estimated to be between 44,000 and 57,000 individual birds.

Historically, bustards inhabited chalk downland in central southern England and in the open sandy Brecklands of eastern England. Archaeological evidence shows the species was native, rather than introduced.

Great Bustards were probably breeding in 11 counties in England, and possibly in a few others. Their fragmented range therefore extended over some 400km, probably with little interchange between the separate populations. This suggests a sizeable total population in England.

Great Bustards are now found across the northern hemisphere in Eurasia, from Iberia, central Europe, and Morocco in the West to Russia to Mongolia and China in the East.

The Great Bustard is omnivorous, meaning it eats both animal and plant matter.

Diet is mainly composed of plants during spring, autumn and winter. Typically they take young shoots, leaves, flowers, ripe and unripe seeds but occasionally also rhizomes, bulbs, berries and fruits.

The diet also includes insects, other invertebrates such as worms, small lizards if they are about and even small mammals such as voles or mice.

Young are chiefly insectivorous, but as they grow they increase the proportion of plants eaten.

Feeding action is a swift pick-up of food from the ground and fast ‘snatching’ of vegetation.

Great bustards are known to be highly gregarious birds, meaning they like to hang about in flocks. They form social units termed ‘droves’.

Large, often lose, droves form in winter and wander together in search of food, sometimes joining up with other droves . Males and females live in separate droves and there is a tendency for birds of the same age to keep together.

They walk with an upright stance. Their gait is slow and deliberate but bustards are capable of surprisingly fast dashes with a top running speed of about 30mph. Flight is between 30-100m above ground, with a powerful and regular wing beat action, making rapid progress with a top flight speed of 50mph.

Bustards are diurnal; active during the day time and inactive during the night time.

They are usually silent but their alarm call is a short, deep nasal grunt similar to a bark when flushed or threatened at very close range.

The young have a number of calls including a high plaintive whistle. This is first heard from the egg prior to hatching and it continues until chicks are several months old.

The males mostly rely on visual cues to attract females and do not use sound much apart from the use of a variety of gruff nasal barks and also a soft hollow “umb, umb” sound, which is sometimes heard as the gular (throat) pouch is inflated and deflated during display.

The Lek

Great Bustards attract and mate during the mating system termed ‘lekking’. Males compete for females with an elaborate visual display. The males perform spectacular courtship displays, competing in a lekking system, where they gather at a ‘lek’ or small display ground to try to impress the females.

Lek physical process

During the flamboyant display, males appear to grow in size and seem to change colour from brown to white.

This is done by cocking their tails and completely withdrawing the head and neck onto their backs whilst inflating a huge balloon-like structure in the neck called the gular pouch.

When sexually aroused the male bustards choose their ground, turn their wings and tails inside out in a big puff of white feathers and inflate the gular pouch, a balloon in the neck and erect whiskers near the beak. This “wheel” or “foam-bath” is for the purpose of attracting females, the white feathers are UV reflective, they point their rear to the sun, it is visible from several kilometres.

These birds are polygynous, and one male may mate with as many as five females.

The Great Bustard ‘nest’ is just a scrape in the ground, usually in tall grass or crops.

Eggs

Eggs weigh about 150g, averaging around 80mm tall by 57mm wide.

They vary in colour from grey to green or brownish, with darker blotches.

A typical clutch is 2 or 3 eggs, but sometimes 4 can be found in a nest.

Chicks

The chicks are nidifugous, meaning they are able to leave the nest site when they are about a day old. The female then leads the chicks around as they feed and they do not come back to the nest site.

Males do not help with the chick rearing at all.

In the wild it is thought a natural lifespan may be up to 20 years, but like many animals, they can live longer in captivity.

The great bustard is on the IUCN Red List of Threatened Species and European populations have been in long-term decline.

It has been listed as Vulnerable on the IUCN Red List since 1996.

According to the IUCN Red List, the world’s Great Bustard population is estimated to be between 44,000 and 57,000 individual birds.

A change in farming methods and hunting killed off the last of the British Bustards in 1830s.

Extinction came fairly suddenly, the main decline occurring in less than 30 years, probably as a result of increased predation by humans on eggs, chicks and adult birds.

Unfortunately the bird was regarded as a great delicacy in Britain and the last one was shot and eaten in 1832.

The GBG has created a self-sustaining population of around 100 birds. This is the only successful reintroduction of Great Bustards anywhere in the world.

A Great Bustard features on the Wiltshire flag and the Coat of arms of Wiltshire and Cambridgeshire.