Mudnest builders

(Grallinidae)

Class Aves

Order Passeriformes

Suborder Passeri (Oscines)

Family Grallinidae

Thumbnail description
Medium to large birds with black and white or gray and brown plumage

Size
8–18 in (20–45 cm)

Number of genera, species
3 genera; 4 species

Habitat
Open woodland

Conservation status
Not threatened

Distribution
Australasia

Evolution and systematics

The four species of mudnesters fall into three subfamilies, the Corcoracinae, the Struthideinae, and the Grallininae. Corcoracinae consists of one genus and one species, the white-winged chough (Corcorax melanorhamphos). Struthideinae also has only one genus and one species, the apostlebird (Struthidea cinerea). The Grallininae subfamily contains a single genus with two species, the Australian magpie-lark (Grallina cyanoleuca) and the torrent-lark (G. bruijni) that lives only in the New Guinea highlands. The two species differ in morphology, behavior, and genetics. Grallina have been shown to have biochemical similarities with monarch flycatchers and drongos.

Physical characteristics

The Grallina are medium sized birds with striking black and white plumage. Corcoracinae are larger, with black and white or gray and brown plumage. Juveniles can be distinguished from adults by eye color and, in some cases, plumage.

Distribution

Grallina occur in Australia and New Guinea, whereas Corcoracinae are specific to Australia.

Habitat

All species except the torrent-lark favor open habitats with some trees and water for nesting, and with open ground for foraging. By contrast, torrent-larks are found in forested hills and mountains, usually near fast-flowing streams.

Behavior

Grallina are usually seen in pairs or small family units, while the Corcoracinae live in large groups, sometimes including more than a dozen birds.

Feeding ecology and diet

Torrent-larks, as their name suggests, forage along fast-flowing mountain streams, taking insects from exposed rocks and the water. The magpie-larks are all predominantly ground foragers. The Corcoracinae forage together in scattered groups, moving forward together as they search the ground for food.

Reproductive biology

Most breeding occurs between August and December or February, though in arid areas birds may breed at any time

of year, taking advantage of rain to build their mud nests. Most group members help with building the bowl of mud reinforced with sticks and grass, and lined with fine grass and

fibers. They also take turns incubating eggs and feeding chicks. Clutches of three to five eggs hatch after about 18 days, and chicks leave the nest two to four weeks later. Grallina breed in monogamous pairs, while Corcoracinae are cooperative breeders, meaning that more than two birds provide care in rearing the young from one nest.

Conservation status

The torrent-lark is endemic to New Guinea and choughs and apostlebirds are endemic to Australia, but all four species are widespread, and common in suitable habitat.

Significance to humans

None known.

Species accounts

List of Species

Australian magpie-lark

Grallina cyanoleuca

subfamily

Grallininae

taxonomy

Grallina cyanoleuca Latham, 1801. Monotypic..

other common names

English; Mudlark, peewee, Murray magpie; French: Gralline pie; German: Drosselstelze; Spanish: Alondra Urraca.

physical characteristics

Magpie-larks have striking black-and-white plumage and long legs. Facial plumage patterns differ between males, females and juveniles. Juveniles also differ from adults in having dark eyes and bills, whereas those of adults are white. Males are typically slightly larger than females. Adults are 10–12 in (25–30 cm) long, and weigh 3–4 oz (80–115 g).

distribution

Widespread throughout Australia, except in dry deserts and dense forests. Also in Timor, southern New Guinea, and Lord Howe Island.

habitat

Magpie-larks occupy a diverse range of habitats from coastal to semi-arid.

behavior

Usually seen in pairs or small family groups, though young birds and unpaired adults gather into large nomadic flocks. Breeding pairs defend all-purpose territories throughout the year. Partners advertise territory ownership by performing precisely coordinated antiphonal duets from conspicuous perches around their territories, often accompanying the duet by a synchronized wing display. They defend their territories vigorously against intruders, and attack their own reflections in windows.

feeding ecology and diet

Magpie-larks feed mostly on insects and other invertebrates such as earthworms and freshwater snails, and are common visitors to Australian backyards, foraging on lawns and enjoying the occasional treat of grated cheese.

reproductive biology

Magpie-larks breed in monogamous pairs that tend to stay together for life (though Michelle Hall's study showed the occasional divorce when a better option presented itself!). Males and females share parental care, and may rear more than one clutch over the breeding season. Most juveniles leave their natal territory when they reach independence, though some remain over winter. After leaving their natal territories, juveniles join large semi-nomadic flocks until they form pairs and establish their own territories.

conservation status

Not threatened.

significance to humans

Magpie-larks have adapted well to agricultural and urban environments and are familiar to most Australians. They are welcome residents in pastoral areas as they feed on freshwater snails that are intermediate hosts for a liver-fluke that parasitizes sheep and cattle.

White-winged chough

Corcorax melanorhamphos

subfamily

Corcoracinae

taxonomy

Corcorax melanorhamphos Vieillot, 1817. Monotypic.

other common names

English: Black jay, black magpie; French: Corbicrave leucoptère; German: Drosselkrähe; Spanish: Chova de Alas Blancas.

physical characteristics

Choughs are large sooty black birds with long, curved, black bills, long tails, and large white wing patches that are visible in flight. They have red eyes that become brighter during displays when wings and tail are fanned out and moved up and down. Males and females have similar plumage. Juveniles are fluffier, with brown eyes that change to red over four years. Adults are 17–19 in (43–47 cm) long and weigh 11–12 oz (320–350 g).

distribution

Choughs live in southeastern Australia.

habitat

Open woodland with leaf litter and not much understory.

behavior

Choughs live in groups of about four to 20 birds. Groups usually consist of a breeding pair with offspring from previous years, though small groups of unrelated birds may come together. Groups sometimes even kidnap juveniles from other groups—the bigger the group the better! Chough are excitable and noisy in their interactions within the group, and the whole group joins in to dive-bomb intruders.

feeding ecology and diet

Choughs forage together on the ground, tossing aside leaf litter, probing with their bills and sifting through the soil for insects, worms and other ground-dwelling prey. Rob Heinsohn found that choughs take an unusually long time to learn to forage: juveniles remain dependent on parental care for longer than most other birds, and their foraging skills continue improving over the first four years of life.

reproductive biology

Choughs are unable to raise young successfully unless they have help; large groups communally raise all chicks in the brood, while small groups only manage one or two. This cooperative breeding is primarily due to foraging constraints because small groups raise more chicks if they are given supplementary food. For young choughs, whose own foraging skills are still developing, helping at the communal nest is costly. Chris Boland and co-workers found that if no other group members are around when they deliver food to the nest, young birds are likely to swallow it themselves instead of feeding it to the chicks.

conservation status

Not threatened.

significance to humans

None known.

Apostlebird

Struthidea cinerea

subfamily

Struthideinae

taxonomy

Struthidea cinerea Gould, 1837. A smaller isolated population in the north of Australia may constitute a subspecies with birds that are slightly larger but with smaller bills than the eastern population.

other common names

English; Gray jumper; French: Apôtre gris; German: Gimpelhäher; Spanish: Ave Apóstol.

physical characteristics

Mottled ashy gray plumage with brown wings, black tail, and a short, stubby, black bill. Males and females have similar plumage. Juveniles have fluffy plumage and brown eyes which change to gray after their second year. Adults are 11–13 in (29–33 cm) long and weigh 4–5 oz (120–140 g).

distribution

Apostlebirds occur in the inland of eastern Australia, and in a smaller, isolated population in northern Australia.

habitat

Dry, open forest with some water.

behavior

Apostlebirds are gregarious birds, foraging, breeding and roosting together. Their name stems from the belief that they live in groups of twelve, though group sizes vary from about three to 20. Apostlebirds are sedentary, defending a territory during the breeding season and wandering further afield after nesting finishes, when groups may aggregate at sources of food or water.

feeding ecology and diet

Apostlebirds are predominantly granivorous, collecting seeds from the ground and crushing them with their stout bills. They also eat insects opportunistically.

reproductive biology

Like other members of the group, apostlebirds build nests of mud. Graeme Chapman's study showed that family members share nest building, incubation, and feeding of chicks. Large groups may produce several broods in a single breeding season.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

Ivison, T. "Magpie-larks" and "Mud-nest builders". In Finches, Bowerbirds and Other Passerines of Australia, edited by Robert Strahan. Sydney: Angus and Robertson, 1996.

Morcombe, Michael. Field Guide to Australian Birds. Archerfield: Steve Parish Publishing Pty Ltd, 2000.

Periodicals

Boland, C.R.J., R. Heinsohn, and A. Cockburn. "Experimental manipulation of brood reduction and parental care in cooperatively breeding white-winged choughs." Journal of Animal Ecology 66 (1997): 683–691.

Boland, C.R.J., R. Heinsohn, and A. Cockburn. "Deception by helpers in cooperatively breeding white-winged choughs and its experimental manipulation." Behavioral Ecology and Sociobiology 41 (1997): 251–256.

Chapman, Graeme. "The social life of the Apostlebird Struthidea cinerea." Emu 98 (1998): 178–183.

Hall, Michelle L. "The importance of pair duration and biparental care to reproductive success in the monogamous Australian magpie-lark." Australian Journal of Zoology 47 (1999): 439–454.

Hall, Michelle L. "The function of duetting in magpie-larks: conflict, cooperation, or commitment?" Animal Behaviour 60 (2000): 667–677.

Heinsohn, Robert G. Slow learning of foraging skills and extended parental care in cooperatively breeding white-winged choughs." American Naturalist 137 (1991): 864–881.

Michelle L. Hall, PhD