Kingfishers (Alcedinidae)

(vertebrate zoology) The kingfishers, a worldwide family of colorful birds in the order Coraciiformes; characterized by large heads, short necks, and heavy, pointed bills.

(Alcedinidae)

Class: Aves

Order: Coraciiformes

Suborder: Alcidines

Family: Alcedinidae

Thumbnail description
Small to medium-sized birds with a large head, long pointed bill, compact body, short neck, and small weak feet; plumage often black, white, or reddish, with areas of iridescent blue or green; bill and feet often black or bright red, orange, or yellow when adult; iris usually dark brown; flight fast and direct on rounded wings with short tail, but central tail feathers elongated in some species

Size
4–18 in (10–46 cm); 0.3–16.4 oz (9–465 g)

Number of genera, species
14 genera; 91 species

Habitat
Wide range of wooded or aquatic habitats, from arid savanna to dense rainforest or from sea coast to high mountain streams

Conservation status
Endangered: 1 species; Vulnerable: 11 species; Near Threatened: 12 species. Most populations face local threats to their habitat from logging of tropical forests, pollution of waterways, and development of oceanic islands

Distribution
Cosmopolitan; on all continents except Antarctica

Evolution and systematics

Kingfishers are a clearly defined group of birds, usually classified as the family Alcedinidae within the avian order Coraciiformes. They are most often placed in the suborder Alcidines, along with two small groups of birds from Central America, todies (family Todidae) and motmots (family Momotidae). Their other near relatives are bee-eaters (family Meropidae), while they appear to be more distantly related to rollers (family Coraciidae), hoopoes (families Upupidae and Phoeniculidae), hornbills (family Bucerotidae), and possibly even trogons (family Trogonidae).

The earliest fossil kingfishers are known from deposits that date to the relatively recent Lower Eocene, about 40 million years ago. These deposits in Wyoming are complemented by even more recent deposits from Germany and France, and also by material less than 25 million years old from Australia. This suggests that kingfishers have always been widely distributed across the world, including during the last two million years, when fossils similar to or identical with modern species have also been recorded from Australia, New Caledonia, Israel, Europe, North America, and Brazil. However, kingfishers form part of the radiation of coraciiform perching birds that was already well-established by about 60 million years ago, soon after the end of the Cretaceous era, so even more ancient fossils can be expected.

The 91 species of modern kingfisher can be divided easily into three groups. These are usually recognized as the subfamilies Halcyoninae, Alcedininae, and Cerylinae. However, each group is so distinct that each is sometimes elevated to the level of a family. Despite the clarity of these divisions, the relationships among the subfamilies and of the species within them remain unresolved. Traditional evidence, from morphology and behavior, suggests that the halcyonines are the least advanced kingfishers and that the cerylines and alcedinines are more advanced and more closely related to one another. More recent molecular studies, based on the technique of DNA-DNA hybridization, suggest that the alcedinines are least advanced and that the halcyonines and cerylines are most advanced and closely related. The main analysis by Hilary Fry in 1980 is based on certain assumptions. First, the inhabitants of stable habitats, such as rainforest, are more likely to be ancestral than species of recently habitable land, such as post-glacial Europe and North America or newly emerged islands. Second, species with unspecialized hunting techniques, such as simple sitand-wait hunting from a perch to the ground, will precede more specialized modes of foraging, such as hawking insects or hovering over fish. Third, that singular species, such as the shovel-billed kookaburra (Clytoceyx rex), are more likely to be ancestral than larger groups of similar species, such as the collared (Halcyon chloris), sacred (Halcyon sancta), and chattering (Halcyon tuta) kingfishers.

Halcyoninae is the best match to these assumptions as the ancestral group. It has a number of species in primitive rain-forest habitats, especially in Indonesia and New Guinea. It has many species that hunt using generalized techniques, yet it has a number of specialized and distinctive species. It includes the largest of all kingfishers, the kookaburras (genus Dacelo), of which the well-known laughing kookaburra (Dacelo novaeguineae) of Australia is the biggest. A number of other large species, all in Australasia or nearby Indonesia, show such affinities to kookaburras as similar call structure, raising the tail when calling, or blue color on the rump. These include the shovel-billed kookaburra, the striking white-rumped kingfisher (Caridonax fulgidus), and maybe even the smaller banded kingfisher (Lacedo pulchella). The unusual hook-billed kingfisher (Melidora macrorrhina), and the spiky-eared lilac-cheeked kingfisher (Cittura cyanotis) also show some affinities with kookaburras. However, they show other similarities to paradise kingfishers (genus Tanysiptera), named for their handsome blue-and-white plumage, red bill, and long racquettipped central tail feathers. The kookaburras are similarly linked, via the white-rumped Halcyon fulgida and moustached Halcyon bougainvillei kingfishers, to the genus Actenoides (considered part of Halycon in Peters). The remaining species of this subfamily are not obviously specialized, other than having juveniles with faint barring on the breast. However, because some smaller groupings are evident among them and because there are so many species, they are usually separated into four genera for convenience. Pelargopsis (three species) have large stork-like bills, while Syma (two species, considered part of Halycon in Peters) have serrated edges to their yellow bills. The remainder are all extremely similar but can be divided into Halcyon species of Asia and Africa, and the various forms of blue-green and white Todiramphus (20 species, considered part of Halycon in Peters) of Asia and Australasia with their white collar, dark eye patch and, in some species, blue or reddish breast.

The subfamily Alcedininae offers a much simpler arrangement, with only two genera to contain these small, mainly piscivorous kingfishers of Africa and Asia, several of which have the second toe reduced or absent. They include the smallest of the dwarf or pygmy kingfishers of the genus Ceyx (11 species), several with reddish upperparts, all inhabitants of forest and woodland, feeding mainly on small insects, and most with a red, dorsally flattened bill when adult. The remainder are combined in the genus Alcedo (9 species), most of which feed predominately on fish, have blue upperparts and a blue breast band, and a long, black, laterally flattened bill. The common kingfisher (Alcedo atthis) of Eurasia is probably the best-known member of this genus. Some African species form a link between these two genera, with blue backs but red bills, which sometimes leads to their separation as a third genus Corythornis in other treatments.

The third subfamily, Cerylinae, is the only one with members in the Americas, including all members of the green-backed genus Chloroceryle (four species). All species feed mainly on fish and appear closely related to the smaller alcedinines. The cerylines include the largest piscivorous species in the genus Megaceryle (four species, considered part of Ceryle in Peters), each with pied-and-reddish plumage and inhabiting one of the continents of the Americas, Africa, or Eurasia. Finally, the pied kingfisher (Ceryle rudis) of Africa and mainland Asia, also with sexually dimorphic bands across the breast, is sometimes placed in its own genus Ceryle but only because of its smaller size and specialized hover-hunting behavior.

Physical characteristics

Kingfishers are a uniform and distinctive group of birds, all immediately recognizable as members of the Alcedinidae. They are small to medium-sized birds with a large head, long pointed bill, compact body, short neck, small legs, and weak feet. Kingfishers' feet have three front toes that are fused at their bases. Most have a fast direct flight on rounded wings and a short tail. The greatest differences are in overall form; the shape of the bill, from narrow and dagger-like to broad and shovel-like; or the development of long central tail feathers. Species range in mass from the 0.3–0.4 oz (9–11 g) African dwarf kingfisher (Myioceyx lecontei) to the 6.7–16 oz (190–465g) laughing kookaburra (Dacelo novaeguineae). The sexes of most species are similar in size. In a few species, one or the other sex is slightly larger, but only in the two largest species of kookaburra are the females markedly larger, while in some paradise kingfishers the males have longer streamers to the central tail feathers.

The sexes of most species are also similar in plumage, bill, and foot color, while juveniles are generally similar to adults except that the bill is often a dull black. Most species have at least some iridescent blue or green in the plumage, offset by large areas of black, white, or brown. The bill and feet are black or brown in many species, but in others one or other appendage may be bright yellow, orange, or red. The iris is dark in most species, with only three exceptions. In many of the cerylines and halcyonines, the sexes are distinguishable through differences in the color of the breast bands or back, but only in two species of the alcedinines is there obvious sexual dichromatism.

The bill shape is generally suggestive of feeding habits, being laterally flattened and dagger-like in species that regularly dive into water after slippery aquatic prey, but dorsoventrally flattened and more scoop-like in species that catch small animals on the ground, and especially wide in those forest species that dig in soil or leaf litter for their prey. One species has a hook and another has serrations at the tip of the bill, but both are of unknown function.

The eyes of kingfishers are also specialized for sighting prey. Ganglion cells that connect the light-sensitive cone cells on the retina are especially dense across a horizontal streak, at each end of which is a depression or fovea packed with cone cells and, by its shape, especially sensitive to movement across its surface. The outer or temporal fovea includes the area of binocular vision, while the inner or nasal fovea covers monocular vision and is also especially densely packed with ganglion cells. The angles of the streak and the well-connected nasal fovea coincide with what would be predicted for birds that search below them for prey and are especially sensitive to movement in their peripheral monocular vision. The birds' ability to turn the head through a wide angle allows fixation of the object with the binocular vision of the temporal fovea. The cone cells of kingfishers are also especially rich in the droplets of red oil that signal excellent color vision. One species has already tested positive for vision near the ultraviolet range.

Species that dive into water in pursuit of prey also have to cope with the problem of the different refractive indices of air and water, and the effect that this has on the apparent location of an object due to bending of light rays at the surface. Tests have shown that pied kingfishers are able to compensate for this, mainly by increasing the dive angle and speed as the depth of prey below the water increases. This species, the most specialized piscivore of all kingfishers, also has a bony plate on the prefrontal area that slides across and screens the eyes as the head strikes the water.

Distribution

Kingfishers are cosmopolitan as a family, occurring on all ice-free continents, but with an uneven distribution of species. Only one subfamily, Cerylinae, occurs in the New World, with a few species in continental North America and a few more tropical species in Central and South America. The remaining species of the subfamily are virtually restricted to sub-Saharan Africa and the Asian mainland. The other two subfamilies, Halcyoninae and Alcedininae, occur across Africa, Asia, and Australasia, with a few species that extend north into the Paleoarctic regions of Europe, the Middle East, and continental Asia. Only members of the halcyonine genus Todiramphus extend east of Australia into the oceanic islands of the Pacific.

Most species of kingfisher are found in the Australasian region of Australia, New Guinea, and Indonesia east of Bali and Sulawesi, some of these on the oceanic islands of the Pacific. Many species are found in the adjacent areas of western Indonesia and the Sunda or Malesian region of the Malay peninsula, the islands of Borneo, Java, and Sumatra, and also the Philippines. Fewer species are found on the Asian mainland and in India and the Middle East, with only a few more in the Afrotropical region of sub-Saharan Africa and Madagascar. Only one, the common kingfisher, extends north into Europe. Species have been recorded for more than one region where appropriate, depending on the extent of their known breeding and non-breeding distributions.

Habitat

Habitats that provide both food and nest sites are essential to all kingfishers. Most kingfishers have the ability to excavate their own nests in soft earth, wood, or termite nests, besides the use of natural cavities, yet nest sites often remain the most limiting resource. Species that feed mainly on aquatic animals extend from arid seashores to small mountain streams, provided that there are earth banks or termite nests into which most species will excavate their nest tunnels. Species that feed on terrestrial prey occur from arid savanna, provided that there are banks or natural tree holes in which to nest, to dense rainforest, with its greater abundance of nest sites. A subjective analysis of the main habitat requirements suggests that 31 species are primarily aquatic, whether they occupy forest or not; 44 species feed mainly in closed-canopy forests; and 17 species are most abundant in wooded savanna. Only aquatic species occur in the New World, while forest-dependant species predominate in Asia and Australasia and savanna species in Africa.

Behavior

Most kingfishers are territorial as breeding pairs, but a few species, such as the laughing kookaburra and pied kingfisher, live as cooperative groups that consist of a pair with several non-breeding helpers. Most species are sedentary, but a few, such as the belted kingfisher (Megaceryle alcyon) of North America and the gray-headed kingfisher (Halcyon leucocephala) of Africa, perform regular nocturnal migrations between breeding and non-breeding areas. All but one species are diurnal, although the hook-billed kingfisher is probably joined by the shovel-billed kookaburra in the nights of the New Guinea forests. Many species bathe by diving repeatedly into water, especially after becoming soiled in the smelly nest cavity. Most species roost alone on a perch within vegetation, rarely in an old nest cavity. Sometimes juveniles roost with adults, and a few species, especially the pied kingfisher, gather at communal roosts for part of the year. All species are highly vocal, with a variety of distinct calls that assist in their location and identification. Loud calls are used to advertise territories, while communication between mates or with offspring is often quieter.

Feeding ecology and diet

Kingfishers eat a wide range of small animals and are capable of taking prey from the ground, water, air, or foliage. Most species spend much of their time perched on the lookout for prey, and only a few expend energy to hover or hawk after prey. Despite their name, none of the kingfishers feed exclusively on fish, and ignore aquatic animals for their diet. Most are adaptable and consume a range of relatively large invertebrates, especially grasshoppers in savanna, earthworms in forest, and crustacea in water; as well as small vertebrates, especially reptiles, fish, and amphibia. Only three species have been reported eating fruit: two eating fruit during winter at high northern latitudes, and the other eating the nutritious fruits of oil palms in the African tropics. Where several species occur together, each has a preferred habitat, such as open or closed forest; each prefers a particular size of prey; and each employs a predominant foraging technique, such as hovering, digging, or exploiting the forest canopy. A species may also alter its feeding patterns in different areas of its range, depending on the other species with which it overlaps. After capture, prey is usually carried back to and beaten against a perch with the bill until it is soft enough to swallow. A few species follow otters, platypus, cormorants, egrets, cattle, or army ants for any prey they might disturb. Others attend grass fires for the insects they disturb.

Reproductive biology

Males of most species call frequently to advertise and defend their territory. Aerial pursuit, exposure of plumage patterns in special joint displays, and courtship feeding of the female by the male are all reported prior to copulation and nesting. Food is always held head-out in the bill during breeding to allow its passage to the female or chicks. Both sexes take some part in nest excavation and cavity choice, usually in an earth bank, less often in rotten wood or in a terrestrial or arboreal termite's nest, and occasionally in a natural tree hole. Excavation is started by flying bill-first into the surface, continued later by pecking and scraping out debris with the bill or feet. The entrance tunnel, 3–26 ft (1–8 m) long depending on site and species, usually leads into a larger nest cavity, but no special lining is added. In most species, each pair nests alone, but a few species breed cooperatively, whether they are attended by helpers or nest together in a colony. Kingfisher eggs are white, round, and shiny. An egg is normally laid daily, but the size of an average clutch, ranging from two to seven, depends on the species. Both sexes usually take part in incubation and care of the young, although the female usually remains at the nest overnight. Incubation takes two to four weeks, and the nestling period three to eight weeks, related to the size of the species. Chicks hatch naked and blind, with the upper mandible of the bill notably shorter than the lower. Later, when the feathers emerge, they are retained in their quills initially, giving the chicks a prickly porcupine-like appearance. There is no nest sanitation, other than that chicks may loosen soil from the chamber walls to partly cover their droppings. Nests, especially those in earthen tunnels, often become smelly and full of maggots as feces and food remains accumulate. The chicks continue to be fed by the parents after fledging. They become independent within a few days or weeks and are sexually mature within a year.

Conservation status

The main threats to kingfishers are the clearing of their rainforest habitats and the draining or pollution of their aquatic habitats. These problems are exacerbated for species with a small total range or population, such as the Endangered Marquesas kingfisher (Halcyon godeffroyi), which lives on an island. A different threat comes from the lack of biological information about many species, so that it is difficult to plan for their conservation. Twelve species are considered threatened in some way and at least two subspecies have become extinct within historic times. All occur in Southeast Asia and Oceania; all but one inhabit forest; all but one is restricted to islands; and most occur in the Philippine center of endemic species.

Significance to humans

Kingfishers were featured in Greek mythology and on Egyptian friezes. Skulls of yellow-billed kingfishers (Syma torotoro) were worn as hair decorations in New Guinea, while the calls or sightings of some species were observed as omens, good or bad, by people of New Guinea and Borneo. Victorians added kingfishers to their collections of stuffed birds, drawn by the royal blue of the common kingfisher that gives the group its name. Kingfishers form part of legends among Arawak and Arikana tribes of Guyana and the Missouri River, respectively. Early in the twentieth century, the laughing kookaburra became an important symbol of Australia. Many other examples of human-kingfisher interaction probably exist. Currently, several species are persecuted for eating fish stocks bred for angling or farming.

Species accounts

Resources

Fry, C.H., K. Fry, and A. Harris. Kingfishers, Bee-eaters and Rollers. Halfway House, South Africa: Russel Friedman Books, 1992.

Sibley, C.G., and J.E. Ahlquist. Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven and London: Yale University Press, 1990.

Woodall, P.F. "Family Alcedinidae (Kingfishers)." In Handbook of Birds of the World. Vol. 6, Mousebirds to Hornbills, edited by J. del Hoyo, A. Elliott, and J. Sargatal. Barcelona: Lynx Edicions, 2001.

Fry, C.H. "The Evolutionary Biology of Kingfishers (Alcedinidae)." Living Bird 18 (1980): 113–60.

Fry, C.H. "The Origin of Afrotropical Kingfishers." Ibis 122 (1980): 57–64.

Woodall, P.F. "Morphometry, Diet and Habitat in the Kingfishers (Aves: Alcedinidae)." Journal of Zoology, London 233, no. 1 (1991): 79–90.

Coraciiformes Taxon Advisory Group.

[Article by: Alan C. Kemp, PhD]