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White-winged fairywren

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White-winged Fairy-wren
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Passeriformes
Family:
Maluridae
Genus:
Malurus
Species:
M. leucopterus
Binomial name
Malurus leucopterus
Dumont, 1824

The White-winged Fairy-wren (Malurus leucopterus) is a species of bird in the Maluridae family. It is endemic to dryer parts of central Australia, stretching from western Queensland and South Australia across to Western Australia, and is part of the large order of passerines. Like other fairy-wrens, it exhibits marked sexual dimorphism with one or more males of a social group adopting brightly coloured plumage during the breeding season. The female is sandy-brown with light blue tail feathers and is smaller in size than the male. The nuptially plumaged male has a bright blue body, black bill, and white coloured wings. However, younger but sexually mature males are almost indistinguishable from females and make-up a large proportion of the breeding males each year. As a result, a troop of White-winged Fairy-wrens are typically observed as small, inconspicuous brown birds accompanied by one or more blue older males in the spring and summer months. Three subspecies are recognised, with one occurring on Dirk Hartog Island and another on Barrow Island off the coast of Western Australia. Males of these island forms have black rather than blue plumage in breeding season.

The White-winged Fairy-wren is found in heathland and arid scrubland, where low shrubs provide cover. It is predominantly insectivorous. Like other fairy-wrens, the White-winged Fairy-wren is notable for several peculiar behavioural characteristics; birds are socially monogamous and sexually promiscuous, meaning that although they form pairs between one male and one female, each partner will mate with other individuals and even assist in raising the young from such pairings. Male wrens pluck petals and display them to females as part of a courtship display.

Taxonomy

The White-winged Fairy-wren was described in 1824 by French ornithologist Charles Dumont de Sainte-Croix, its specific epithet derived from the Ancient Greek leuko- 'white' and pteron 'wing'.[2] It is a member of the maluridae family and is one of 12 species in its genus, Malurus. It is most closely related to the Australian Red-backed Fairy-wren; both of which make-up a phylogenetic clade sister to the White-shouldered Fairy-wren of New Guinea.[3] The White-winged fairy-wren was originally named the Blue-and-white Wren, and early observers, such as Norman Favaloro of Victoria, refer to them by this name [4]. However, studies have shown that the fairy-wrens are not in fact closely related to the true wrens (family Troglodytidae). Like over half of bird species worldwide, the fairy-wrens are passerines.

Subspecies

There are, at present, three recognized subspecies of Malurus leucopterus:

  • M. l. leuconotus is endemic to mainland Australia and distinct in that they are the only subspecies to have nuptial males showing prominent blue-and-white plumage.[5] The specific epithet is derived from the Ancient Greek leukos 'white' and notos 'back'.[2]
  • M.l. leucopterus are present on Dirk Hartog Island, off the western coast of Australia, and nuptial males display black-and-white plumage. [5]
  • M.l. edouardi, like M.l. Leucopterus, have black-and-white coloured males, and are found only on Barrow Island, also off the western coast of Australia.[5]

M.l. leucopterus and M.l. edouardi are typically smaller than their mainland relatives, and both subspecies tend to have smaller family groups consisting of only one male and one female, with an occasional helper.[6] While the island species and mainland species have been found to have similar social structure, breeding pairs on both islands have, on average, smaller clutches, longer incubation times, and fewer living fledglings.[6] Additionally, while M.l. leuconotus is considered of least concern by the IUCN due to its widespread availability, both island subspecies are considered vulnerable by the Australian government due to their delicate nesting sites that are easily disturbed by human construction and habitation.[1]

Evolutionary History

Both island subspecies are closer in distance to mainland populations of leuconotus; Dirk Hartog is 2 km (1¼ mi) from the mainland while Barrow Island is 56 km (35 mi) from the mainland. They were last connected to each other at the beginning of the present interglacial 8,000 to 10,000 years ago.[5] As a result, it has long been thought that both subspecies are more closely related to the mainland species than they are to each other, and recent genetic data has supported this.[7] At present, there are three possible situations from which the three races of white-winged fairy-wren could have evolved. The first suggests that black-and-white plumage is an ancestral condition and following separation of the three populations, blue-and-white plumage evolved in the mainland species.[5] The second hypothesis suggests that black-and-white plumage evolved convergently on the two separate islands.[5] The third suggests that black-and-white plumage evolved once from the blue-and-white ancestral condition, and later the mainland species re-evolved blue plumage.[7]

Description

White-winged fairy-wrens are one of the two smallest species of Malurus and males typically weigh between 7.2 g (0.25 oz) and 10.9 g (0.38 oz) while females weigh between 6.8 g (0.24 oz) and 11 g (0.39 oz).[8] Fully matured adults are sexually dimorphic, as the males are larger and differ in color from the females. Adult females are sandy-brown with very light blue tails and nuptially plumed males have black bills, blue or black bodies (depending on subspecies), and white wings.[8] Both have long, distinct tails at an upward angle from their bodies.

Nestlings, fledglings, and juveniles exhibit brown plumage and pink-brown bills and their tails are shorter than those of adults. Immature males develop medium-blue tail feathers and darker bills by late summer or fall (following a spring or summer breeding season), while young females develop light-blue tails. By the subsequent spring, all males are fertile and have developed cloacal protuberances, which stores sperm. In contrast, fertile females develop oedematous brood patches, or a bare area on their bellies, during the breeding season. [8] Males entering their second or third year may develop spotty blue and white plumage during the breeding season. By their fourth year, males have assumed their nuptial plumage, where the scapulars, secondary wing coverts, and secondary flight feathers are white while the rest of their bodies exhibit a vibrant cobalt-blue. All sexually mature males molt twice a year, before and after the breeding season, and during the winter months males are almost indistinguishable, apart from their black bills, from the females.[8] Breeding males' blue plumage, particularly the ear-coverts, is highly iridescent due to the flattened and twisted surface of the barbules.[9] The blue plumage also reflects ultraviolet light strongly, and so may be even more prominent to other fairy-wrens, whose colour vision extends into this spectrum.[10]

Vocalisations

Tideman in 1980 characterized 5 different patterns of calls among Malurus leucopterus leuconotus and were recognized by Pruett and Jones among the island subspecies l. edouardi:[11]

  • Reel: The main call made by both sexes in order to establish territory and unify the group. It is a long song of “rising and falling notes” that it first signaled by 3-5 “chips”.
  • Harsh: Often used to establish contact (especially between mothers and their young) and to raise alarm, it is characterized by a series of “loud and abrupt” calls that vary in frequency and intensity.
  • Contact: Used between adults in the bush, these calls are high-pitched peeps that may be made intermittently with reels.
  • High Pips: Quiet, high-pitched, and short calls, given by nestlings, fledglings, and females around the nest. When used by a mature female, they are mixed with harsh calls.
  • Juvenile: “Gurgling” noises made by nestlings when they are fed. The subordinate helpers and feeders may make this sound as well.

Distribution and Habitat

The White-winged Fairy-wren is particularly well adapted to dry environments, and M.l. leuconotus is found throughout arid and semi-arid environments between latitudes 19 and 32 S in mainland Australia They commonly cohabit with other species of fairy-wren, including the Purple-backed Fairy-wren (M. lamberti assimilis). White-winged fairy-wrens often inhabit heathlands or treeless shrublands dominated by Atriplex, Marieana, Triodia, or Zygochloa.[8] Meanwhile, M. l. leucopterus inhabits similar habitats on Dirk Hartog Island and M. l. Edouardi does the same on Barrow Island.[6]

Behavior

White-winged Fairy-wrens live in one of the most complex social groups of their genus. Larger clans are comprised of 2-4 birds, typically consisting of one brown or partially blue male and a breeding female. Nest helpers may or may not be present; although helpers are normally a brown male or female, and occasionally, a juvenile from a previous brood. Several subgroups live within one territory and make up a clan—which is flown over by one nuptially plumed blue (or black) male. While the blue male is dominant to the rest of the brown and partially blue males within his clan, he nests with only one female and contributes to the raising of only her young. It is unclear whether or not he copulates and fathers any of the other nests within his territory.[8]

Nonetheless, each clan has a specified area of land that all members contribute to foraging from and defending—although these orders may vary year to year. Frequently, territory sizes (normally 4-6 ha) are correlated with the abundance of rain and resources in a region, where smaller territories occur where insects and resources are plentiful.[8] Additionally, territories expand during the winter months when these birds spend much of their time foraging with the entire clan.

Adults and their young may be preyed upon by exotic mammalian predators, such as the red fox (Vulpes vulpes) or the feral cat (Felix catus), and native predatory birds and reptiles.[11] Additionally, many nests are destroyed during breeding season by human habitation (and even the occasional bird watcher) because the nests are hidden close to the ground and as a result, are difficult for the passers-by to spot.[4]

Feeding

The white-winged fairy-wren is primarily insectivorous, a diet which includes moths, praying mantises, spiders, caterpillars, and various smaller insects.[11] The larger insects are typically fed to nestlings by the breeding female and her helpers, including the breeding male. Adults and juveniles forage by hopping along the shrubland floor, and may supplement their diets with seeds and fruits. [12]

Breeding

Breeding females begin to build their nests in the spring, constructing domed structures composed of spiderwebs, fine grasses, thistle-down, and vegetable-down, typically 6-14 cm tall and 3-9 mm.[8] Nest have a small entrance on one side and they are normally placed in thick shrubs close to the ground. A clutch of 3-4 eggs is generally laid beginning in September and continue through to January. Incubation times for clutches laid in September and October were 15 days and 14 days in November and December clutches.[8] Incubation was by the breeding female alone, while the breeding male (a brown or blue male) and nest helpers aided in feeding the nestlings. Nestlings remained in the nest for 10-11 days, and fledglings were continued to be fed for 3-4 weeks following their departure from the nest. Fledglings either stayed on to help raise the next brood or moved to a nearby territory. It is not unusual for a pair bond to hatch and raise two broods in one breeding season, and helpers tend to lessen the stress on the breeding female rather than increase the overall number of feedings.[8] Like other fairy-wrens, the white-winged fairy-wren was particularly prone to parasitic nesting by the Horsfield's Bronze-Cuckoo (Chalcites basalis).[8]

Courtship

Fairy-wrens exhibit one of the highest amounts of extra-pair mating and many broods are brought up by male other than the natural father. However, courtship methods among White-winged Fairy-wrens remain unclear. Blue-plumaged males have been seen outside of their territory and in some cases, carrying pink or purple petals, which among other species, advertise the male to neighboring females. In contrast, black-plumaged males on Barrow and Dirk Hartog islands often carry blue petals.[8] While petal-carrying outside of clan territories is indicative of extra-pair copulations, further genetic analysis is necessary.

References

  1. ^ a b Template:IUCN2006
  2. ^ a b Liddell, Henry George and Robert Scott (1980). A Greek-English Lexicon (Abridged Edition). United Kingdom: Oxford University Press. ISBN 0-19-910207-4.
  3. ^ Christidis L, Schodde R. 1997, "Relationships within the Australo-Papuan Fairy-wrens (Aves: Malurinae): an evaluation of the utility of allozyme data". Australian Journal of Zoology, 45 (2): 113–129.
  4. ^ a b Favaloro, N. 1940, "Notes on the Blue-and-white Wren", Emu, vol. 40, no. 4, pp. 260-265.
  5. ^ a b c d e f Pruett-Jones, S. & Tarvin, K.A. 2001, "Aspects of the ecology and behaviour of White-winged Fairy-wrens on Barrow Island", Emu, vol. 101, no. 1, pp. 73-78.
  6. ^ a b c Rathburn, M.K. & Montgomerie, R. 2003, "Breeding biology and social structure of White-winged Fairy-wrens (Malurus leucopterus): comparison between island and mainland subspecies having different plumage phenotypes", Emu, vol. 103, no. 4, pp. 295-306.
  7. ^ a b Driskell, A.C., Pruett-Jones, S., Tarvin, K.A. & Hagevik, S. 2002, "Evolutionary relationships among blue- and black-plumaged populations of the white-winged fairy-wren (Malurus leucopterus)", Australian Journal of Zoology, vol. 50, no. 6, pp. 581-595.
  8. ^ a b c d e f g h i j k l Rowley, I. & Russell, E. 1995, "The Breeding Biology of the White-winged Fairy-wren Malurus leucopterus leuconotus in a Western Australian Coastal Heathland", Emu,vol. 95, no. 3, pp. 175-184.
  9. ^ Rowley, Ian (1997). Bird Families of the World:Fairy-wrens and Grasswrens. Oxford: Oxford University Press. pp. p. 44. ISBN 0-19-854690-4. {{cite book}}: |pages= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  10. ^ Bennett ATD, Cuthill IC (1994). "Ultraviolet vision in birds: what is its function?". Vision Research. 34 (11): 1471–78. doi:10.1016/0042-6989(94)90149-X. PMID 8023459.
  11. ^ a b c Tidemann, S. 1980, "Notes on breeding and social behaviour of the White-winged Fairy-wren Malurus leucopterus", Emu, vol. 80, no. 3, pp. 157-161.
  12. ^ Schodde R. 1982, The fairy-wrens: a monograph of the Maluridae. Lansdowne Editions, Melbourne.
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