Logrunners and chowchillas

(Orthonychidae)

Class Aves

Order Passeriformes

Suborder Passeri (Oscines)

Family Orthonychidae

Thumbnail description
Small, stocky ground birds with powerful legs and shafts of tail feathers extending as spines

Size
7.3–11.8 in (18.5–30 cm); 0.10–0.47 lb (47–213 g)

Number of genera, species
1 genus; 3 species

Habitat
Rainforest and contiguous thick, low secondary growth

Conservation status
Not threatened

Distribution
Eastern Australia and central ranges of New Guinea

Evolution and systematics

The taxonomic placement of these unusual birds was long problematic. Traditionally they were included with other ground-frequenting passerines of the Australian and New Guinean region, such as quail-thrushes and whipbirds. The DNA-DNA hybridization studies by Charles Sibley and Jon Ahlquist in 1980–90s demonstrated that logrunners were quite distinct from these and other passerine families. Since then they have been separated at family level, an action supported by subsequent research, within the Australo-Papuan corvine radiation. They comprise one of the older groups, with fossil species known from Miocene and Quaternary deposits in Australia.

The distribution of the species has attracted much attention. The southern species, the southern logrunner (Orthonyx temminckii) occurs through central eastern Australia, then apparently leapfrogs the larger, darker chowchilla (O. spaldingii) of northeastern Australia, to reappear in the central ranges of New Guinea. This unusual pattern was illuminated in 2001 by Leo Joseph and his colleagues, who showed that the New Guinea populations were specifically distinct from those in southeastern Australia; they thus take the name New Guinea logrunner (O. novaeguineae). It is not certain, however, to which of the Australian species it is most closely related.

Earlier names for the Australian species were the southern and northern logrunners for O. temminckii and O. spaldingii, respectively. When the New Guinea populations were considered to be conspecific with O. temminckii, the common name of the latter was deemed inappropriate and shortened to logrunner; the name for O. spaldingii was changed to chow-chilla, a rendering of its distinctive call. Now, with the logrunners split into two species, it seems appropriate to qualify the name of the Australian birds by reintroducing the traditional name, southern logrunner. The name logrunner is used collectively for the birds of this family.

The morphology of the hind limb and pelvis reflects the characteristic ground feeding method used by these birds. The femur has a distinctive hour-glass shape bestowed by the expansion of the distal end as a brace and the proximal end for muscle attachments. The pelvis is broad, with deep excavations for the powerful muscles that drive the legs.

Physical characteristics

Logrunners are stocky birds, with the chowchilla, the largest species, reaching a length of 12 in (30 cm); the other species are noticeably smaller (7.3–8.3 in; 18.5–21 cm). All have powerful legs and claws. The unspecialized bill is of

moderate strength. Perhaps the most curious physical feature of these birds is the stiffened shafts of the 10 tail feathers, the tips of which protrude beyond the ends of the feathers as pliable spines. This led to the earlier name of "spine-tailed logrunner." While the chowchilla is simply colored with broad patches of unmarked black and white, and in one sex, orange, the other two species have much more complex patterns of brown, rufous, black, gray, and white. All three species have similar patterns of sexual dimorphism: males have white breasts, females orange ones.

Distribution

This family is found only in Australia and New Guinea. The southern logrunner is distributed along coastal areas and adjacent ranges in appropriate habitat from central eastern New South Wales north to southeastern Queensland. The chowchilla is restricted to the Atherton Tableland region in northeastern Australia, particularly above 1,475 ft (450 m). New Guinea birds occur along the central highlands in a zone 6,500–9,300 ft (1,980–2,840 m), in places above and below this. There are breaks in the distribution, some of which are real and others that may merely reflect our poor knowledge of this rare species.

Habitat

Logrunners are birds of the rainforest, although they will venture into contiguous habitats if the vegetation is sufficiently low and thick; this can include invasive, introduced plants.

Behavior

Logrunners live in permanent territories in pairs or small family parties. In 1999 Amy Jensen reported that these groups of 2–5 birds occupied home ranges (the areas in which they foraged) of 1.7–9.8 acres (0.7–4.0 ha), substantially larger than the space actually defended. Territorial defense is strong, birds announcing themselves to neighboring families with loud calls. For the first hour after dawn they call constantly before settling down to feed. They also break into short bouts of calling throughout the day, particularly during encounters with neighbors along a border, and have a concluding burst at dusk. Mike McGuire investigated the vocalizations of several parties of chowchillas. His 1999 study recorded vocabularies of often complex calls with differing local dialects between adjoining groups.

These birds can be quite shy, quickly fleeing into cover, often with a loud shriek, when startled. At other times, they can be remarkably tame, ignoring quiet observers while they search for food—even walking across a person's feet while the bird is foraging.

Feeding ecology and diet

The purpose of the spine-tipped tail and oddly shaped femur become apparent when logrunners feed. A feeding bird spreads its tail and rests the spine-like quills against the ground. To expose the soil, the bird rakes a foot through the leaf litter and fallen sticks, throwing the leg to the side, perpendicular to the body. Once the ground is sufficiently cleared to feed, the legs are used alternately to scratch the soil front to back in search of insects, larvae and other invertebrates that form the diet, balancing on one leg while at the same time using the tail as a supporting prop. Pivoting around the tail, logrunners produce distinctive small cleared patches about 8 in (20 cm) in diameter on the forest floor. A foraging bird spends a brief period scratching at the one spot before moving on to another a short distance away. Smaller ground-feeding birds, such as the yellow-throated scrubwren (Sericornis citreogularis) and eastern whipbird (Psophodes olivaceus), may attend foraging logrunners, picking up small invertebrates that are unearthed by the scratching.

Reproductive biology

Unlike many Australian passerines, southern logrunners concentrate much of their breeding in the winter. Starting in about April or June their nesting season continues through to August or September, sometimes as late as October. The female is responsible for building the nest and incubating the eggs, and she provides most of the care for the young.

The nest is a globular dome, usually placed on the ground but on occasion may be situated in low vines or on a fallen log or a stump. The female builds a platform up to 2 in (5 cm) of short, thick sticks. She adds curving sides until these meet and join at the top, finally capping this with dry leaves and green moss. This roof hangs over the side entrance, partially concealing it and keeping the interior of the nest dry, even in heavy downpours. The clutch characteristically comprises two eggs, which are large and white. Usually these hatch after a 21–25 day incubation period. The female has most of the responsibility for feeding the nestlings, but she is assisted by the male; he passes food to her, which she in turn gives to the young birds. The young remain in nest for 16–18 days. After fledging they are fed by both parents. Juveniles have a mottled breast, which on the subsequent moult acquires the color appropriate to the bird's sex.

The breeding biology of the chowchilla, which was long unknown, was revealed in 1997 by Cliff Frith and his associates. Most aspects are similar to those of the southern logrunner, with some important differences. Nesting can occur in any month of the year, peaking in July through December. The nest is the same shape but considerably larger. Only a single egg is laid. Both incubation and nestling periods are longer: 25 days, with 75% of eggs hatching, and 22–27 days, with 67% of young successfully leaving the nest. More than one male may bring food to the female, but males do not themselves feed the chick.

What is known of the breeding in New Guinea logrunners is similar, with records from March and November of nests with single eggs.

Conservation status

The clearance of rainforest has eliminated southern logrunners from parts of the range; however, this species appears capable of persisting in small, isolated patches of rainforest. A population persists to the south of the metropolis of Sydney, New South Wales, well separated from the northern section of its range, and a pair of birds was found in 5 acres (2 ha) of rainforest that had been long-isolated within a surrounding countryside of dairy land. The possibility that proliferating exotic plants, such as lantana and blackberry, in and around the rainforest might force this species from its habitat did not eventuate. The southern logrunner seems to have adapted well to thick stands of these plants, using their cover to colonize along watercourses and even moving away from rainforests into areas where these vigorously invading plants have made inroads into cleared land.

While clearing has undoubtedly reduced the habitat available to chowchillas, this species remains common in northeastern Australia. The New Guinea logrunner appears to be uncommon to rare, but this may be due in part to its shy nature and the remoteness of much of its range. Only in 1987 was it discovered at Tari Gap, central New Guinea, where it had long been thought to be absent.

Significance to humans

The restricted habitat and cryptic behavior of these interesting birds make them unfamiliar to most people. The name "chowchilla" is the name used by the Dyirbal Aboriginal people, itself derived from this bird's call.

Species accounts

List of Species

Southern logrunner

Orthonyx temminckii

taxonomy

Orthonyx temminckii Ranzani, 1822, Hat Hill, New South Wales, Australia.

other common names

English: Spine-tailed logrunner; French: Orthonyx de Temminck; German: Stachelschwanzflöter; Spanish: Corretroncos Cola de Espinas.

physical characteristics

7.3–8.3 in (18.5–21 cm); female 0.1–0.13 lb (46–58 g), male 0.13–0.15 lb (58–70g). Gray and tan patterned plumage with black side-stripe. Males have white throats; orange throats in females.

distribution

Central eastern Australia.

habitat

Rainforest, edges of contiguous wet sclerophyll forest, and dense fringing vegetation, including introduced species.

behavior

Sedentary. Territorial throughout year, usually living in pairs or small family parties. Often shy, but generally ignores human observers when foraging. Generally unobtrusive except when giving loud, penetrating calls; most characteristic a lengthy rapid series of "weet" notes; also a piercing "kweek" when alarmed.

feeding ecology and diet

Eats insects and other small soil invertebrates uncovered by vigorous scratching; leaves characteristic shallow depressions in soil.

reproductive biology

Breeds May to August, sometimes April to October; produces one or two broods per season. Female alone builds nest, incubates, and provides most of care for young. Nest is a dome of sticks and other vegetation with a side entrance overhung by moss; placed on or near ground against trunk or clump of vegetation. Two white eggs are laid. Incubation, 21–25 days; fledging period 16–18 days.

conservation status

Not threatened. Common in northern part of range, decreasing southwards until rare at southern limits.

significance to humans

None known.

New Guinea logrunner

Orthonyx novaeguineae

taxonomy

Orthonyx novae guineae Meyer, 1874, Arfak Mountains, New Guinea. Three subspecies.

other common names

French: Orthonyx de Nouvelle Guinée; German: Neuguineaflöter; Spanish: Corretroncos de Nueva Guinea.

physical characteristics

7.3 in (18.5 cm); female 0.10–0.13 lb (47–58 g), male 0.12–0.17 lb (53–75g). Similar to southern longrenner.

distribution

Scattered localities in mountains of New Guinea between 6,500–9,300 ft (1,980–2,840 m), probably up to 11,300 ft (3,450 m); occurs locally as low as 3,900 ft (1,200 m) in Irian Jaya. O. n. novaeguineae: northwestern New Guinea; O. n. dorsalis: western central New Guinea;O. n. victoriana: eastern New Guinea.

habitat

Mainly upper montane forest.

behavior

Terrestrial. Quiet, cryptic, and easily overlooked. Usually seen in pairs or small parties of three or four birds. Song is series of four to six descending notes.

feeding ecology and diet

Scratches in ground litter for insects and other invertebrates.

reproductive biology

The nest is a small dome of moss, root fibers, and plant stems, about 5 in (12.5 cm) wide placed on the ground. Nests with a single white egg found in March and November.

conservation status

Generally scarce to rare, although not considered a threatened species.

significance to humans

None known.

Chowchilla

Orthonyx spaldingii

taxonomy

Orthonix spaldingii Ramsay, 1868, Rockingham Bay, Queensland, Australia. Three subspecies.

other common names

English: Northern logrunner; French: Orthonyx de Spalding; German: Schwarzkopfflöter; Spanish: Corretroncos de Spalding.

physical characteristics

11–11.8 in (28–30 cm); female 0.25–0.32 lb (113–144 g), male 0.33–0.47 lb (150–213 g). Dark brown upperparts; breast is white in males and orange-brown in females. Thin white eye ring.

distribution

O. s. spaldingii: northeastern Australia; O. s. melasmenus: northeastern Australia, north of O. s. spaldingii. Generally above 1,470 ft (450 m), locally in lowlands with highest rainfall.

habitat

Rainforest.

behavior

Territorial at all seasons, often living in family parties. Highly terrestrial. Often shy, but may be confiding when feeding. Generally unobtrusive except when calling. Loud, ringing "chow chowchilla chowry chook chook" or "chow chilla chow chow chilla"; also other growls, chucks.

feeding ecology and diet

Forages by vigorous scratching, excavating shallow depressions in ground. Eats insects and other terrestrial invertebrates; occasionally seeds.

reproductive biology

Breeds almost year round, mainly April to August; one or two broods reared per season. Female lays a single white egg and is responsible for construction of nest, incubation of eggs, and

care of nestlings. Male provisions female during activities. Nest is a dome of sticks, twigs, and moss, side entrance hooded by moss, platform of sticks leading to entrance; on or near ground in clump of vegetation. Incubation, 25 days; fledging 22–27 days.

conservation status

Not threatened. Although some reduction of range has occurred through habitat loss, this species is still common.

significance to humans

None known.

Resources

Books

Coates, Brian J. The Birds of Papua New Guinea. Vol. 2, Passerines. Alderley: Dove Publications, 1993.

Higgins, P. J., and J. M. Peter, eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol. 6, Pardalotes to Figbird. Melbourne: Oxford University Press, forthcoming.

Schodde, R., and I. J. Mason. The Directory of Australian Birds. Passerines. Collingwood: CSIRO Publishing, 1999.

Periodicals

Frith, C. B., D. W. Frith, and A. Jensen. "The Nesting Biology of the Chowchilla Orthonyx spaldingii (Orthonychidae)." Emu 97 (1997): 18–30.

Hindwood, K. A. "The Spine-tailed Log-runner (Orthonyx temminckii)." Emu 33 (1934): 257–67.

Jensen, A. "Home Ranges and Group-territoriality in Chowchillas Orthonyx spaldingii." Emu 99 (1999): 280–90.

Joseph, L., B. Slikas, D. Alpers, and R. Schodde. "Molecular Systematics and Phylogeography of New Guinean Logrunners (Orthonychidae)." Emu 101 (2001): 273–80.

McGuire, M. "Dialects of the Chowchilla Orthonyx spaldingii in Upland Rain Forest of North-eastern Australia." Emu 96 (1996): 174–80.

Organizations

Birds Australia. 415 Riversdale Road, Hawthorn East, Victoria 3123 Australia. Phone: +61 3 9882 2622. Fax: +61 3 98822677. E-mail: [email protected] Web site: <http://www.birdsaustralia.com.au>

Walter E. Boles, PhD