Superb starling

Lamprotornis superbus
Starlings (Sturnidae)

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The superb starling (Lamprotornis superbus) is a member of the starling family of birds. It was formerly known as Spreo superbus. They are long-lived birds that can live over 15 years in captivity.

Description

This species is 18 to 19 cm (7.1 to 7.5 in) in height. These small short-tailed starlings have a long narrow bill, robust bodies, strong feet and a distinctive plumage pattern. Their spectacular iridescent plumage is due to the arrangement of melanin granules within the feathers, resulting in structural blues and greens, rather than colors derived from pigments. The appearance of the superb starling is very similar to the Hildebrandt's starling, also found in East Africa. The superb starling is distinguished by having pale creamy-white eyes, as opposed to red eyes in the Hildebrandt's. Moreover, only adult superb starlings have a white breast band.

Adult Plumage

In the adult plumage, superb starlings have a bronzy-black crown and ear-coverts. The area between the eye and the bill on the side of their head (the lore) is black. Almost all their body is a blue-green glossy color; the chin, the throat, the chest, the nape, the mantle, their back, and their uppertail-coverts. The nape area displays the most prominent blue tones. A slender white strip divides the glossy chest from the red-orange abdomen, flanks, and thighs. The vent, as well as the underside of the tail and wings, are white. On the wings, the primary feathers 6-9 show an inward curve on the inner web, whereas primaries 5-8 have tapered outer web. The glossy metallic-green wings have dark black spots on the median and grater coverts. Their irises are creamy-white. Their legs and their bills are black. The superb starlings are sexually monomorphic, which means that both sex lookalike. However, in captive pair, males appear to have a wider white breastband.

Juvenile Plumage

Juveniles have duller plumage. There are distinct plumage regions, but there is no glossy sheen except on the tail and wing feathers. The iris appears brown at first, later grayish white. The bill has a pale yellowish color with darkening on the tip. The legs are brown. By seven months, the bird acquires adult plumage, although the eyes remain dark, and there is yellow coloring at the base of the bill.

Taxonomy

The superb starling belongs to the largest genus of African starlings Lamprotornis. The tail has a variable length, and the genus was originally split into short-tailed Lamprocolius and long-tailed Lamprotornis. However, scientists agreed that the genus did not need to be split, since the long tails seemed to have evolved independently on multiple occasions. Lamprotornis species typically feature a glossy blue or green color on their back. They usually have a pattern of hollow, oval, melanin granules in a layer close to the surface of the feather barbules. Some granules are additionally scattered within the barbules.

The superb starling was originally thought to be a member of the Spreo genus. However, over time, the species from the Spreo genus changed considerably. Scientists reclassified some species of Spreo, including the superb starling, making the glossy species belong to the Lamprotornis genus. The classification of the superb starling was challenging, since its behavior was different than the other species of the Lamprotornis genus. However, DNA hybridization data indicate that the superb starling is part of the Lamprotornis genus.

Habitat and Distribution

The superb starling lives in the savanna, thornbush and acacia arid areas, open woodland, lakeshore woodlands, gardens and cultivated fields, at an elevation of 0–2,650 metres (0–8,694 ft) above sea level. They tend to avoid humid lowland areas. This species has a very large range and can commonly be found in East Africa, including Ethiopia, Somalia, Uganda, Kenya, South Sudan, and Tanzania. Superb Starlings typically occupy large territories, often exceeding 50 hectares (0.50 km²). When they are not on their territories, they are usually searching for food or heading to water sources. Their group can have more than 40 individuals. The sex ratio in those is approximately equal. In the non-breeding season, being the dry season, the groups of superb starlings live with other starling species such as the Hildebrandt’s starling (Lamprotornis hildebrandti) and the greater blue-eared glossy starling (Lamprotornis chalybaeus). They have also been observed with other bird species such as the red-billed buffalo weaver (Bubalornis niger) and the white-headed buffalo weaver (Dinemellia dinemellii) in the Serengeti National Park, in Tanzania. Mixed species flocks might aid in obtaining food and serve as a defense mechanism against predators. When it is the breeding season however, the superb starlings are territorial and chase the birds of other species from the group, especially when they approach their nests.

Behavior

Vocalizations

The superb starling has a long and loud song consisting of trills and chatters. At midday it gives a softer song of repeated phrases. There are several harsh calls, the most complex, which is described as "a shrill, screeching skerrrreeee-cherrrroo-tcherreeeeeet." Additionally, superb starlings produce warning chirr and a reapeated whit-chor-chi-vii when they are excited. Some scientists compare their vocalizations to the Common Starling (Sturnus vulgaris), and others to the European Robin (Erithacus rubecula).

In Amboseli National Park in Kenya, vervet monkeys (Cecopithcus aerhiops) have acquired the ability to identify and respond appropriately to the unique alarm calls made by the superb starlings in the presence of aerial and terrestrial predators.

Diet

The superb starling feeds primarily on the ground, often below, or in the vicinity of acacia trees. They are omnivorous. They predominantly rely on insects as their main food source, such as termites (Termitidae), grasshoppers, moth larvae (Lepidoptera), beetles (Carabidae), mantids (Mantidae) and ants. They also feed on berries, small fruits, and seeds. Occasionally, they scavenge on animal carcasses. Additionally, they can also extract nectar from sisal flowers, Agave sisalana. Usually, superb starlings are rather tame and unafraid of people. They scavenge around settlements and picnic sites to find food as well. Unfortunately, Superb starlings in Tanzania cause harm to grapevines in vineyards, and they also disturb sprouting wheat crops as they dig them up.

Reproduction

The breeding season lasts from October to February in Ethiopia, from March to June in Somalia. Superb starlings have been observed running on the ground, jumping with drooping wing and outstretched heads, indicating what is thought to be a form of nuptial display.

Nests

Free-standing nests are constructed in thorn trees bushes, although there have been reports of nests in tree holes and even cliffs or rock crevices. The nests in the thorn trees are positioned at 1.5–6 metres (4.9–19.7 ft) above the ground and are well guarded by the thorns. They also sometimes nest at the base of raptor nests for protection. The superb starlings make their own nests, and both sex help with the nests, which are large structures made of twigs lined with dry grass, featuring an entrance on one side. On occasion, they can take over nests belonging to White-headed Buffalo Weavers (Dinemellia dinemelli), sometimes rejecting the existing eggs.

Nestling and Parental Care

Superb starlings’ eggs are uniformly dark blue, measuring 24–26 millimetres (0.94–1.02 in) x 18–19 millimetres (0.71–0.75 in) and weighting 4.5 g. Females lay 3-4 eggs. Based on captive breeding, the incubation period lasts 12–13 days, and the surprisingly short nestling period ranges from 18–24 days. Only the females incubate. Nestlings are fed insects, primarily caterpillars and grasshoppers. Superb starlings form large social groups in which both breeding parents and 1-14 alloparents contribute to the care of the offspring. It appears that both members of the breeding pair are involved in raising the young until they achieve independence. The individuals who’s provisioned or nestled has been observed carrying food in their bills and did not seem to regurgitate. Starlings lack a crop and may lack a mechanism to prevent digestion of food items in transit. Consequently, they might be compelled to transport insects in their bills to avoid damaging such easily digested prey.

Social Dynamics

In superb starlings, individuals of both sexes can either choose to forego dispersal (remaining residents of their birth group) or become immigrants (leaving their birth group). Immigrants, being unrelated to the resident individuals of the group they join, may experience ongoing conflict with the residents throughout their lives. Resident females never breed within their natal groups. Both resident and immigrant males have to opportunity to attain breeding status within the same social group during a breeding season. Indeed, despite the presence of reproductively capable resident males and unrelated potential mates, immigrant males often seize breeding opportunities within their new social groups. Apart from the potential inclusive fitness benefit gained by assisting in raising their offspring, superb starlings also benefit from being social on the group and individual levels. Living in larger social groups enhances an individual’s chances of survival and reduces reproductive variance within the group. This is likely because larger predators are actively confronted by the group, with a greater resource availability in the territories inhabited by larger groups.

Bibliography

Colin Harrison & Alan Greensmith: Vögel. Dorling Kindersly Limited, London 1993, 2000, ISBN 3-831-00785-3
Bryan Richard: Vögel. Parragon, Bath, ISBN 1-405-45506-3

References

Zimmerman, Dale A.; Turner, Donald A. & Pearson, David J. (1999). Birds of Kenya and Northern Tanzania, Field Guide Edition. Princeton University Press. pp. 172–173, 514. ISBN 0-691-01022-6.