Family CORACIIDAE

Eurystomus orientalis

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Family CORACIIDAE

Compiler and date details

R. Schodde & I.J. Mason, CSIRO Australian National Wildlife Collection, Canberra, Australia

Introduction

Coraciidae (true rollers) comprise about 11–13 species in two genera; one species occurs in Australia. There is as yet no fossil record for Australia. Like Meropidae, rollers are centred in the Palaeotropics, from Africa through southern Eurasia to Indonesia.

Rollers are perching birds that are usually rather solitary and fly acrobatically from high exposed perches in wide sweeps and convolutions both in display and to capture insects and other small animals on wing (Eurystomus Vieillot, 1816) or often from ground (Coracias Linnaeus, 1758). Nests are in unlined holes in trees and banks; eggs are plain-white and ovoid; and young are altricial, nidicolous, and become spiny because developing feathers long retain their horny sheaths; nidificational duties are shared by both sexes.

Family-group Systematics

Although at times combined with the closely allied ground rollers, Brachyteraciidae Bonaparte, 1854, and Madagascan cuckoo-roller, Leptosomidae Blyth, 1838 (e.g. Sharpe 1892; Peters 1945; Mayr & Amadon 1951), the true rollers (Coraciidae Rafinesque, 1815) are separated at family level here, following Cracraft (1971). This arrangement is supported by Stresemann (1927–1934), Wetmore (1960), Wolters (1975–1982), Maurer & Raikow (1981), Burton (1984), Sibley et al. (1988) and Sibley & Ahlquist (1990). Even so, the status of these groups does not appear to be well settled.

Genus-group Systematics

Eurystomus Vieillot, 1816—Circumscription of aerial-feeding Eurystomus Vieillot, 1816, with three or four species, has been settled since Sharpe (1892). The validity and value of subgenera in so small and compact a group is uncertain, cf. Wolters (1975–1982); they are not used here.

Species-group Systematics

Eurystomus orientalis (Linnaeus, 1766)—Specific limits have been clarified by the revisions of Stresemann (1913), Boetticher (1936), Ripley (1942), Mees (1965) and Scholtes in White & Bruce (1986); but the status of subspecies in the Indonesian archipelagos is not so settled. Australian E. o. pacificus (Latham, 1802), nevertheless, is distinct in its pallid toning, disproportionally short tail and rather more pointed wings adapted for migration.

Excluded Taxa

Vagrant Species: CAVS:8082
CORACIIDAE: Coracias garrulus Linnaeus, 1758 [European Roller]

Diagnosis

Stout, medium-sized, blue-, green- and sometimes chestnut-tinted birds with broad heads, tapering to blunt tails, and thick slightly hooked bills with slit-like nostrils; body feathering rather coarse, in defined tracts; aftershafts moderately developed; uropygial gland naked, flattened. Feet small, anisodactylous; short tarsi coarsely scutellate on acrotarsia, and all three forward toes basally syndactylous to first joint. Sexes alike. Wings rounded but long: 10 primaries plus remicle, moulting in unconfirmed sequence, and 12 diastataxic secondaries; tail short: 12 rectrices, moulting in unconfirmed sequence. Nares holorhinal/amphirhinal, impervious, nasal septum imperforate; desmognathous palate heavily braced for crushing, with very narrow vomer, long broadly round-winged palatines, and lachrymals greatly expanded to reach small spur-like ectethmoids and jugal bars; basipterygoid processes rudimentary or absent; cervical vertebrae 13–14; sternum deeply two-notched on each side, only spina externa present, furcula without hypocleideum. Musculus expansor secundariorum fully developed but no biceps slip; pelvic muscle formula AXY, no M. ambiens, deep plantar tendons Type V and complexly fused. Carotid arteries paired. Syrinx tracheo-bronchial with one pair of intrinsic muscles. Tongue narrow without fringe at base; no crop; caeca present, elongated. Diploid karyotype of 70–90 chromosomes, with three to six pairs of macrochromosomes.