Roller Bird

The name of the Old World birds' family is Coraciidae which are simply known as rollers because of their aerial acrobatics which they perform during courtship as well as territorial flights. In size & build, they look similar to the crows whereas in appearance resembles kingfishers. Their inner two front toes are said to be connected but not the outer ones. They are insect eaters and monogamous or used to nest in an unlined hole of a tree or masonry. They are warmer regions birds who used to lay 2 - 4 eggs and 3 - 6 eggs in the tropics or at higher latitudes respectively. Their eggs hatch after 17 to 20 days whereas their young ones used to remain in the nest for another 30 days.

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Roller Bird - Description

They are medium-sized birds that resemble crows in terms of size and build whereas they look similar to kingfishers as well as bee-eaters. They have strong and slightly hooked beaks as well as stocky bodies with often brightly coloured plumage. In length, they range from 25 - 27 centimetres i.e 10 - 11 in. They have a large head, short legs and neck, weak feet and bright plumage. They are said to be similar to their relatives in general morphology. The inner front toes are said to be connected but not the outer ones. Their feet weakness, as well as their legs, can be observed in their behaviour as they don't hop and move along their perches. 

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Key Points

Taxonomy and Systematics

The Coraciidae family of rollers was considered to be introduced by Constantine Samuel Rafinesque by the French polymath in 1815. Coraciidae is known to be one of the 9 families in the order Coraciiformes and which also includes bee-eaters, motmots, ground rollers, todies, cuckoo rollers as well as three families of kingfishers. These families are not particularly closely related to the rollers except ground rollers. Therefore, probably Coraciiformes are polyphyletic. It gets its Scientific name from Latin as coracium i.e " like a raven" whereas it got the English name from aerial acrobatics that some of the birds use to perform. Thus, their English name is the roller. 

Distribution

These birds are said to be found in the warmer regions of the world. The continent of Africa has most of the species of this bird and is said to have originated from here. The fossils show that they were also present in North America in the Eocene. They can be found in warmer regions of Asia, Africa, Europe, Australia as well as South Pacific Islands. In Madagascar, ground rollers can be found. If we talk about the European roller, it is a migratory bird that breeds in Europe whereas it spends its winters in Africa. From Western Asia to Indian Subcontinent, Indian Rollers can be found.

Breeding and Feeding

We have already mentioned above that they are monogamous and used to lay 2 - 4 eggs or 3 - 6 eggs in the tropics as well as in higher latitudes respectively. When it comes to defending the nesting sites or their territories, they are said to be very noisy as well as aggressive and used to patrol their territories. They used to attack the intruders with rolling dives. Their eggs are white in colour which hatch usually after 17 to 20 days but their offspring used to remain there for another 30 days and when they hatch, they are naked, blind as well as helpless. 

If we talk about the feeding habits of Coracias rollers, they are known as wait and watch type hunters who used to sit on a tree before directly descending on their targeted prey and used to carry it back in the beak to the perch. They used to have terrestrial invertebrates as well as small vertebrates. For example, young birds, frogs, lizards, etc.  They also intake various items which are usually avoided by the other birds such as warning colouration type of insects, hairy caterpillars or snakes. If we talk about the Eurystomus rollers, they used to hunt on the wings and used to run down suddenly on the crickets, flying beetles and others whereas azure roller as well as dollar bird used to hunt on huge swarms which appears after the thunderstorms such as swarms of termites or flying ants etc. 

Indian Rollers

Indian Roller is a very colourful bird whose scientific name is Coracias benghalensis and it is also known as the Indian blue jay bird. They are known for their aerobatic display in the breeding season. They are seen along the roadsides, grasslands and in forests. Indian Rollers do not come under the category of migratory birds. Some of the states in India consider them as a symbol. The names of the states like Karnataka, Andhra Pradesh, Bihar and Orissa. The Indian roller state bird is of Karnataka (India).  Indian Rollers are found to be in Asia. They live in places from Iraq and the United Arab Emirates in South-Western Asia through the Indian subcontinent. Along with this, they are in Sri Lanka, Lakshadweep and the Maldives Islands. The main place where they live is cultivated areas, forests and grasslands. Indian roller bird can be seen in parks in urban areas. They are carnivorous that's why they eat small insects, snakes, scorpions, frogs and other amphibians.

General Facts

Lilac Breasted Roller

Lilac Breasted Roller is an African bird of the roller family that is Coraciidae. The male and female look similar and the young ones have no long tails. Kenya considers them as their state symbol unofficially. Throughout eastern and southern Africa, they are found. These are found at places like from the Red Sea Coast of Eritrea through east Africa to Southern Africa; at last, they occur together in Namibia, Botswana, Zimbabwe and north-eastern South Africa. Some of them are not gone anywhere while others migrate from northeast Kenya to northwest Somalia for a breed of late April to mid -September. For livelihood, they stay in open woodland and Savanna and the treeless places. For their diet, they get their food as grasshoppers, beetles, lizards, crabs and small amphibians. They took their prey from the ground.

European Roller

European Roller is the only type of roller family that lives in Europe. They are medium in size. They are known for their aerial acrobatics during courtship or territorial flights. They have plumage of bright colour and a hooked bill. European rollers fly indirect light with blue contrasting with Black feathers. Both sexes are the same but the juveniles are colourless versions of adults. They breed in Europe. Their range extends into the Middle East, Central Asia and Morocco. Because of this, they are also known as Eurasian Roller

They like to spend their winter in the southern Sahara in two distinct regions which are in Africa, are from Senegal east to Cameroon and from Ethiopia west to Congo and south to South Africa. Some of them migrate to Africa through India. European rollers prefer lowlands, dry and open places with scattered trees. Oak and pine woodlands with open areas are used for breeding but sometimes farms with mixed vegetation are also used. Their sound of European roller is a harsh crow-like sound and when they are nervous they give a series of harsh sounds. They are carnivores that's why they eat large insects, small reptiles, rodents and frogs etc. Mostly they eat grasshoppers and bush crickets.

Ground Rollers

They are a small family of non-migratory birds. They are found in Madagascar. They resemble kingfishers, bee-eaters and rollers. They are considered as sub-groups of real rollers. They come from the family of Brachypteraciidae. They have crow-like sizes and ranges from 25 to 49 cm and their length ranges between 9.8 - 19.3 in. They eat reptiles as well as large insects. They don't have bright colourful bodies and have a dull appearance as compared to other rollers. They are considered as shy and elusive as their relatives and it becomes difficult to find them in Malagasy forests. They do not dig their nest, unlike other rollers. They nest in the holes in the ground as solitary pairs, unlike the other rollers who don't nest on the grounds. They are known for their tumbling flight and are said to be pigeon size birds.

Conclusion

Thus, we have covered information about roller birds and specifically about flying Indian roller, Lilac-breasted roller and Ground rollers, European rollers. If we talk about the total population of the rollers in the world, that is unknown. Usually, they belong to the warmer regions but can also be found in the temperate regions as well. The common threats to these birds are deforestation as well as a great number of traffic collisions. They can be found in the grasslands or forests areas. This is a solitary bird but during the breeding seasons, they used to live in pairs. They are aggressive when it comes to their nest's defence and got their English name i.e. Roller because of their aerial acrobatics.