Family PODARGIDAE

Podargus strigoides

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Family PODARGIDAE

Compiler and date details

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

Introduction

Podargidae (frogmouths) comprise about 14 species in two genera; all three species of one genus occur in Australia. The Australian fossil record to date (1994) is all Pleistocene, from southwest and southeast Australia but is possibly older. There are two centres of modern distribution: Australo-Papuasia with three species of Podargus Vieillot, 1818, and South-East Asia, Greater Sundas and Philippines with about 11 species of Batrachostomus Gould, 1848.

Frogmouths are nocturnal insectivores/carnivores that, solitary or in pairs, roost by day usually on horizontal forks or in crotches of trees, and fly by night with flap-and-glide action from set perches to snap up food from terrestrial or arboreal surfaces. Nests are constructed flimsily of twigs or down on horizontal branches of trees; eggs are spherical, plain white with little sheen, one or two per clutch; and young are altricial, nidicolous, and covered with dense whitish down which moults through a second long whitish mesoptile down before teleoptile plumage is acquired. Both sexes share nidificational duties (Podargus).

Family-group Systematics

Although Aegothelidae were formerly included as a subfamily (e.g. Hartert 1892; Beddard 1898), Podargidae as defined here have been recognised as a distinct caprimulgiform family by most recent reviewers, see Stresemann (1927–1934), Peters (1940), Mayr & Amadon (1951), Wetmore (1960), Condon (1975), Wolters (1975–1982) and Schodde & Mason (1981). Its two very different genera have themselves since been separated into two families on genomic distance measured by DNAxDNA hybridzation, see Sibley et al. (1988), Sibley & Ahlquist (1990); but the issue is nomenclaturally irrelevant for Australian taxa. Podargus Vieillot, 1818 differs in its large size, broader head, wedged tail and nests of sticks or tendrils, from the small, eared, round-tailed and down-nesting Asian species of Batrachostomus Gould, 1848, see Hartert (loc. cit.), Schodde & Mason (loc. cit.).

Genus-group Systematics

Podargus Vieillot, 1818—Interspecific relationships are unclear. Podargus ocellatus Quoy & Gaimard, 1830, as indicated by its vertical roosting, compound call-notes and cup-shaped nest of tendrils, may stand apart from the two giant species, Australian P. strigoides (Latham, 1802) and New Guinean-centred P. papuensis Quoy & Gaimard, 1830 (Schodde & Mason 1981: 94, 99). Nevertheless, a better understanding of their phylogeny is needed before subgeneric separation can be justified, pace RAOU Checklist Committee (1926).

Species-group Systematics

Podargus papuensis Quoy and Gaimard, 1830—Notwithstanding chequered variation in New Guinea (Mayr 1937; Junge 1937), Australian populations are geographically discrete and morphologically differentiated (Schodde & Mason 1981: 96, 99). Those on Cape York Peninsula are large and sandy-tawny; and those in the wet rainforest bloc of north-eastern Queensland (Endeavour River to Townsville) are small and darker, more chocolate-brown. They intergrade abruptly in the region of the Endeavour and Annan Rivers, north-eastern Queensland (Schodde & Mason 1981: 99).

Podargus ocellatus Quoy and Gaimard, 1830—The forms included by convention in this polytypic species comprise several small and short-tailed subspecies in New Guinea, one small and long-tailed subspecies on Cape York Peninsula, and two much larger and medium- or long-tailed subspecies in the Solomons (P. o. inexpectatus Hartert, 1901) and central-eastern Australia (P. o. plumiferus Gould, 1846). The status of these last two forms needs clarification (cf. Peters 1940; Greenway 1978).

Podargus strigoides (Latham, 1802)—Infra-specific differentiation was rationalized by Hartert (1905), corroborated by Schodde & Mason (1981: 104–105) and refined by Ford (1986). There are three Australian forms: one large, medium-dark and variably mottled in the east; another medium-sized but plainer and duskier in the west and central regions; and a third small and pale in the north. Their geographical limits and zones of intergradation are still poorly documented and need more precise delineation, cf. Schodde & Mason (loc. cit.) and Ford (loc. cit.).
{9999:–1934}

Diagnosis

Medium-sized, heavy-set, bull-headed birds, patterned in camouflaging browns, russets and greys, with extraordinarily broad and thickened slightly hooked bills and basal slit-like nostrils overhung with bunched and burred facial bristles; body feathering soft, almost downy in defined tracts; no downs other than extensive paired powder downs in lumbar region; aftershafts scale-like and reduced; uropygial gland vestigial or absent (Podargus). Feet weak, anisodactylous (hemi-zygodactylous); short tarsi reticulately scaled, outer forward toe with five phalanges and middle toe much the longest; hypotarsus with two closed canals. Sexes alike to somewhat unlike. Wings short and rounded, the trailing edges of remiges frayed: 10 primaries plus remicle moulting in continuous staggered descending mode, and about 14 diastataxic secondaries; tail wedge-shaped (Podargus) or rounded (Batrachostomus): 10 rectrices. Nares holorhinal and impervious, nasal septum imperforate (to perforate); desmognathous palate, with paired vomer hidden beneath maxillo-palatine shelf; expanded notched palatines fused with premaxilla and maxillaries anteriorly to form a broad crushing plate, naso-frontal hinge articulate, lachrymals fused with nasal and maxillary bones, jugal bar flimsy, and ectethmoids rudimentary; basipterygoid processes absent; long dentary bone fused with supra-angular in lower jaw; cervical vertebrae 13; sternum deeply two-notched on each side, only reduced spina externa present, furcula with vestigial hypocleideum. Musculus expansor secundariorum and biceps slip absent, and M. tensor patagium brevis with wristward slip; pelvic muscle formula AXY, no M. ambiens; deep plantar tendons Type V, fused. Single left carotid artery. Syrinx bronchial, with intrinsic muscles attached from seventh to last bronchial rings. Eyes large, tubular, slightly front-facing; tongue membranous, acute; no crop; caeca large, apically dilated. Diploid karyotype of 78 chromosomes, with 5 pairs of macrochromosomes.