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Superb Fairywren - Malurus cyaneus
Superb Fairywren - Malurus cyaneus

[Image: superb%20fairy-wren%2008.jpg]

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Maluridae
Genus: Malurus
Species: Malurus cyaneus

The superb fairywren (Malurus cyaneus), also known as the superb blue-wren or colloquially as the blue wren, is a passerine bird of the family Maluridae, common and familiar across southeastern Australia. The species is sedentary and territorial, also exhibiting a high degree of sexual dimorphism; the male in breeding plumage has a striking bright blue forehead, ear coverts, mantle, and tail, with a black mask and black or dark blue throat. Non-breeding males, females and juveniles are predominantly grey-brown in colour; this gave the early impression that males were polygamous, as all dull-coloured birds were taken for females. Six subspecies groups are recognized: three larger and darker forms from Tasmania, Flinders and King Island respectively, and three smaller and paler forms from mainland Australia and Kangaroo Island.

Like other fairywrens, the superb fairywren is notable for several peculiar behavioural characteristics; the 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 yellow petals and display them to females as part of a courtship display.

The superb fairywren can be found in almost any area that has at least a little dense undergrowth for shelter, including grasslands with scattered shrubs, moderately thick forest, woodland, heaths, and domestic gardens. It has adapted well to the urban environment and is common in suburban Sydney, Canberra and Melbourne. The superb fairywren eats mostly insects and supplements its diet with seeds.

The superb fairywren is one of 12 species of the genus Malurus, commonly known as fairywrens, found in Australia and lowland New Guinea. Within the genus, the superb fairywren's closest relative is the splendid fairywren; these two "Blue wrens" are also related to the purple-crowned fairywren of northwestern Australia.

William Anderson, surgeon and naturalist on Captain James Cook's third voyage, collected the first superb fairywren specimen in 1777 while traveling off the coast of eastern Tasmania, in Bruny Island's Adventure Bay. He named it Motacilla cyanea because its tail reminded him of the European wagtails of the genus Motacilla. Anderson did not live to publish his findings, although his assistant William Ellis described the bird in 1782.< The genus Malurus was later described by Louis Jean Pierre Vieillot in 1816, giving the bird its current scientific name.

Shortly after the First Fleet's arrival at Port Jackson, Sydney, the bird gained the common name superb warbler. In the 1920s came common names wren and wren-warbler—both from its similarity to the European wren—and fairywren. The bird has also been called Mormon wren, a reference to observations of one blue-plumaged bird accompanied by many brown-plumaged birds, which were incorrectly assumed to be all female. The Ngarrindjeri people of the Murray River and Coorong regions called it waatji pulyeri, meaning "little one of the waatji (lignum) bush", and the Gunai called it deeydgun, meaning "little bird with long tail". Both it and the variegated fairywren were known as muruduwin to the local Eora and Darug inhabitants of the Sydney basin.

Like other fairywrens, the superb fairywren is unrelated to the true wren. It was previously classified as a member of the old world flycatcher family Muscicapidae and later as a member of the warbler family Sylviidae before being placed in the newly recognised Maluridae in 1975. More recently, DNA analysis has shown the Maluridae family to be related to the Meliphagidae (honeyeaters), and the Pardalotidae (pardalotes, scrubwrens, thornbills, gerygones and allies) in the large superfamily Meliphagoidea.

Ornithologist Richard Schodde has reported that the subspecific classification of the Superb fairywren requires further review. In 1982, he lumped all forms into two subspecies, the smaller and paler-plumaged M. c. cyanochlamys of the mainland and larger and daker M. c. cyaneus of Tasmania and adjoining islands. However zones of abrupt change led him to split these into more subspecies, and to note that the differences between New South Wales and Queensland populations needed investigation. Six subspecies are recognized:
  • M. c. cyaneus, the nominate subspecies described in 1782, is found throughout Tasmania. Birds are larger and darker than the mainland subspecies, with males having a deeper azure blue coloration. Schodde in his 1982 review reclassified elizabethae and samueli under cyaneus.

  • M. c. elizabethae, endemic to King Island was described as a separate species elizabethae by Archibald James Campbell in 1901. Males have a deeper blue colour than Tasmanian birds. King Island birds also have longer tarsi (lower legs).

  • M. c. samueli, endemic to Flinders Island, has males that are of intermediate colour between the King Island and Tasmanian subspecies.

  • M. c. cyanochlamys, described by Richard Sharpe in 1881, is found on mainland Australia; in general, birds are smaller and paler than those of Tasmania, with Queensland male birds bearing a pale silvery blue crown, ear tufts and mantle.

  • M. c. leggei, described by Gregory Mathews in 1912, is found in eastern South Australia. Males in breeding plumage differ from those of subspecies cyanochlamys by having blue tinges on their belly below the chest band and on their wing remiges.

  • M. c. ashbyi, described by Mathews in 1912, is found on Kangaroo Island, and has been separated from the mainland subspecies for around 9000 years. Birds of this subspecies are larger, have narrower bills and darker plumage than birds on nearby mainland South Australia. Females from Kangaroo Island are more uniformly grey in plumage than mainland birds.

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M. c. cyaneus, M. c. elizabethae, M. c. samueli, M. c. cyanochlamys, M. c. leggei, M. c. ashbyi

Evolutionary history
In his 1982 monograph, Schodde proposed a southern origin for the common ancestor of the superb and splendid fairywrens. At some time in the past it was split into southwestern (splendid) and southeastern (superb) enclaves. As the southwest was dryer than the southeast, once conditions were more favourable, the splendid forms were more able to spread into inland areas. In the east, the superb fairywren spread into Tasmania during a glacial period when the sea level was low and the island was connected with the rest of the continent via a land bridge. What gave rise to subspecies cyaneus became isolated as the sea levels rose. The Bass Strait forms were isolated from Tasmania but more recently and so their subspecific status was not maintained. Further molecular studies may result in this hypothesis being modified.

The superb fairywren is 14 cm (5½ in) long and weighs 8–13 g (0.28–0.46 oz), with males on average slightly larger than females. The average tail length is 5.9 cm (2⅓ in), among the shortest in the genus. Averaging 9 mm (0.4 in) in subspecies cyaneus and 8 mm (0.3 in) in subspecies cyanochlamys, the bill is relatively long, narrow and pointed and wider at the base. Wider than it is deep, the bill is similar in shape to those of other birds that feed by probing for or picking insects off their environs.

Like other fairywrens, the superb fairywren is notable for its marked sexual dimorphism, males adopting a highly visible breeding plumage of brilliant iridescent blue contrasting with black and grey-brown. The brightly coloured crown and ear tufts are prominently featured in breeding displays. The breeding male has a bright-blue forehead, ear coverts, mantle and tail, brown wings, and black throat, eye band, breast and bill. Females, immatures, and non-breeding males are a plain fawn colour with a lighter underbelly and a fawn (females and immatures) or dull greyish blue (males) tail. The bill is brown in females and juveniles and black in males after their first winter. Immature males moult into breeding plumage the first breeding season after hatching, though incomplete moulting sometimes leaves residual brownish plumage that takes another year or two to perfect. Both sexes moult in autumn after breeding, with males assuming an eclipse non-breeding plumage. They moult again into nuptial plumage in winter or spring. Breeding males' blue plumage, particularly the ear-coverts, is highly iridescent because of the flattened and twisted surface of the barbules. The blue plumage also reflects ultraviolet light strongly, and so may be even more prominent to other fairywrens, whose colour vision extends into this part of the spectrum.

Vocal communication among superb fairywrens is used primarily for communication between birds in a social group and for advertising and mobbing, or defending a territory. The basic, or Type I, song is a 1–4 second high-pitched reel consisting of 10–20 short elements per second; it is sung by both males and females. Males also possess a peculiar song-like Type II vocalization, which is given in response to the calls of predatory birds, commonly grey butcherbirds (Cracticus torquatus). The purpose of this behaviour, which does not elicit a response from other nearby wrens, remains unknown. It is not a warning call, but in fact gives away the location of the vocalizing male to the predator. It may serve to announce male fitness, but this is far from certain. Superb fairywrens' alarm call is a series of brief sharp chits, universally given and understood by small birds in response to predators. Females also emit a purr while incubating. Strangely, the bird appears to also use song as a password for its chicks to give it a chance to avoid cuckoo parasites.

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Distribution and habitat
The superb fairywren is common throughout most of the relatively wet and fertile south-eastern corner of the continent, from the south-east of South Australia (including Kangaroo Island and Adelaide) and the tip of the Eyre Peninsula, through all of Victoria, Tasmania, coastal and sub-coastal New South Wales and Queensland, through the Brisbane area and extending inland – north to the Dawson River and west to Blackall; it is a common bird in the suburbs of Sydney, Melbourne and Canberra. It is found in wooded areas, generally with plenty of undergrowth, and has also adapted to urban existence and can be found in gardens and urban parks as long as there is an undergrowth of native plants nearby. Lantana (Lantana camara), a prolific weed in Australia, has also been beneficial in providing shelter in disturbed areas, as has the introduced and invasive blackberry (Rubus spp.) Unlike other fairywrens, it appears to benefit from the urban environment and has out-competed the introduced House Sparrow (Passer domesticus) in one study on the grounds of the Australian National University in Canberra. Colonies of wrens can be found in Hyde Park and the Royal Botanic Gardens in Sydney's urbanized centre. It is not found in dense forest nor in alpine environments. Forestry plantations of pine (Pinus spp.) and eucalypts are also unsuitable as they lack undergrowth.

Like all fairywrens, the superb fairywren is an active and restless feeder, particularly on open ground near shelter, but also through the lower foliage. Movement is a series of jaunty hops and bounces, with its balance assisted by a proportionally large tail, which is usually held upright, and rarely still. The short, rounded wings provide good initial lift and are useful for short flights, though not for extended jaunts. During spring and summer, birds are active in bursts through the day and accompany their foraging with song. Insects are numerous and easy to catch, which allows the birds to rest between forays. The group often shelters and rests together during the heat of the day. Food is harder to find during winter and they are required to spend the day foraging continuously.

The superb fairywren is a cooperative breeding species, with pairs or groups of 3–5 birds maintaining and defending small territories year-round. The group consists of a social pair with one or more male or female helper birds that were hatched in the territory, though they may not necessarily be the offspring of the main pair. These birds assist in defending the territory and feeding and rearing the young. Birds in a group roost side-by-side in dense cover as well as engaging in mutual preening.

Major nest predators include Australian Magpies (Gymnorhina tibicen), butcherbirds (Cracticus spp.), Laughing Kookaburra (Dacelo novaeguineae), currawongs (Strepera spp.), crows and ravens (Corvus spp.), shrike-thrushes (Colluricincla spp.) as well as introduced mammals such as the Red Fox (Vulpes vulpes), cat and Black Rat (Rattus rattus). Superb fairywrens may utilise a 'rodent-run' display to distract predators from nests with young birds. The head, neck and tail are lowered, wings held out and feathers fluffed as the bird runs rapidly and voices a continuous alarm call. A field study in Canberra found that superb fairywrens that lived in areas frequented by noisy miners (Manorina melanocephala) recognised miner alarm calls and took flight, and had learnt to ignore their non-alarm calls, while those that live in areas not frequented by noisy miners did not respond to miner alarm calls. This suggests the species has adapted and learned to discriminate and respond to another species' vocalisations.

Superb fairywrens are predominantly insectivorous. They eat a wide range of small creatures (mostly insects such as ants, grasshoppers, shield bugs, flies, weevils and various larvae) as well as small quantities of seeds, flowers, and fruit. Their foraging, termed 'hop-searching', occurs on the ground or in shrubs that are less than two metres high. Because this foraging practice renders them vulnerable to predators, birds tend to stick fairly close to cover and forage in groups. During winter, when food may be scarce, ants are an important 'last resort' food, constituting a much higher proportion of the diet. Nestlings, in contrast to adult birds, are fed a diet of larger items such as caterpillars and grasshoppers.

Several courtship displays by superb fairywren males have been recorded. The 'sea horse flight', named for its seahorse-like undulations, is one such display. During this exaggerated flight, the male—with his neck extended and his head feathers erect—tilts his body from horizontal to vertical, and descends slowly and springs upwards by rapidly beating his wings after alighting on the ground. The 'face fan' display may be seen as a part of aggressive or sexual display behaviours; it involves the flaring of the blue ear tufts by erecting the feathers.

During the reproductive season, males of this and other fairywren species pluck yellow petals, which contrast with their plumage, and show them to female fairywrens. The petals often form part of a courtship display and are presented to a female in the male fairywren's own or another territory. Males sometimes show petals to females in other territories even outside the breeding season, presumably to promote themselves. Fairywrens are socially monogamous and sexually promiscuous: pairs will bond for life, though both males and females will regularly mate with other individuals; a proportion of young will have been fathered by males from outside the group. Young are often raised not by the pair alone, but with other males who also mated with the pair's female assisting.

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Breeding occurs from spring through to late summer; the nest is a round or domed structure made of loosely woven grasses and spider webs, with an entrance in one side generally close to the ground, under 1 m (3 ft), and in thick vegetation. Two or more broods may be laid in an extended breeding season. A clutch of three or four matte white eggs with reddish-brown splotches and spots, measuring 12 x 16 mm (0.45 x 0.6 in). The eggs are incubated for 14 days, after which they hatch within 24 hours. Newborn chicks are blind, red and featherless, though quickly darken as feathers grow. Their eyes open by day five or six and are fully feathered by day 10. All group members feed and remove fecal sacs for 10–14 days. Fledglings are able to feed themselves by day 40 but remain in the family group as helpers for a year or more before moving to another group or assuming a dominant position in the original group. In this role they feed and care for subsequent broods and repel cuckoos or predators. Superb fairywrens also commonly play host to the brood parasite Horsfield's bronze cuckoo (Chrysococcyx basalis) and, less commonly, the shining bronze cuckoo (C. lucidus) and fan-tailed cuckoo (Cacomantis flabelliformis).

How birds learn foreign languages
Biologists have succeeded in teaching wild birds to understand a new language

Date: July 16, 2015
Source: Australian National University
Biologists have succeeded in teaching wild birds to understand a new language. After only two days of training, fairy wrens learned to flee when they heard an alarm call that was foreign to them, showing that birds can learn to eavesdrop on the calls of other species.

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fairy wren.

Biologists have succeeded in teaching wild birds to understand a new language.

After only two days of training, fairy wrens learnt to flee when they heard an alarm call that was foreign to them, showing that birds can learn to eavesdrop on the calls of other species.

The research, led by biologists at The Australian National University (ANU), could be used to help train captive animals to recognise signals of danger before they are released in to the wild.

"The first bird we tested lived on the ANU campus near my office. There was general disbelief and excitement when the bird learned the task perfectly," said the leader of the study, Professor Robert Magrath, from the ANU Research School of Biology.

"We had been doing experiments on learning using different methods, but until then with little success. So it was exciting to finally crack the practical problems of carrying out this experiment, and get clear results."

Many animals get information about danger by eavesdropping on each other, but how they do it has been an ongoing puzzle.

"Recognizing other species' calls is a remarkable ability, because there are lots of species in a natural community, and lots of different types of calls. It's like understanding multiple foreign languages," Professor Magrath said.

The biologists trained the fairy-wrens by playing unfamiliar sounds to them, while throwing a model glider of a predatory bird, a currawong or a sparrowhawk, over them.

After only eight playbacks the birds had learned to flee, while they did not flee when played unfamiliar sounds that had not been paired with the gliders.

Story Source: Australian National University. "How birds learn foreign languages: Biologists have succeeded in teaching wild birds to understand a new language." ScienceDaily. (accessed July 16, 2015).

Journal Reference:
Robert D. Magrath, Tonya M. Haff, Jessica R. Mclachlan, Branislav Igic. Wild Birds Learn to Eavesdrop on Heterospecific Alarm Calls. Current Biology, 2015 DOI: 10.1016/j.cub.2015.06.028

•Vertebrates benefit by eavesdropping on other species’ alarm calls
•We used model predators and playback to test if wild birds learn about novel alarms
•Individual birds learned to recognize novel sounds as alarm calls
•Such rapid learning explains eavesdropping on acoustically diverse alarm calls

Many vertebrates gain critical information about danger by eavesdropping on other species’ alarm calls, providing an excellent context in which to study information flow among species in animal communities. A fundamental but unresolved question is how individuals recognize other species’ alarm calls. Although individuals respond to heterospecific calls that are acoustically similar to their own, alarms vary greatly among species, and eavesdropping probably also requires learning . Surprisingly, however, we lack studies demonstrating such learning. Here, we show experimentally that individual wild superb fairy-wrens, Malurus cyaneus, can learn to recognize previously unfamiliar alarm calls. We trained individuals by broadcasting unfamiliar sounds while simultaneously presenting gliding predatory birds. Fairy-wrens in the experiment originally ignored these sounds, but most fled in response to the sounds after two days’ training. The learned response was not due to increased responsiveness in general or to sensitization following repeated exposure and was independent of sound structure. Learning can therefore help explain the taxonomic diversity of eavesdropping and the refining of behavior to suit the local community. In combination with previous work on unfamiliar predator recognition, our results imply rapid spread of anti-predator behavior within wild populations and suggest methods for training captive-bred animals before release into the wild . A remaining challenge is to assess the importance and consequences of direct association of unfamiliar sounds with predators, compared with social learning—such as associating unfamiliar sounds with conspecific alarms.

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  • Claudiu Constantin Nicolaescu, OldGreenVulture
The trouble with being a handsome bird

Date: June 28, 2017
Source: Monash University

Male birds often use brightly colored plumage to be attractive to females. However, such eye-catching trimmings may also attract unwanted attention from predators. Now, a new study led by Monash University has found that showy males indeed perceive themselves to be at a greater risk of predation.

The study's lead author, PhD student Alex McQueen, from the School of Biological Sciences, studied risk-taking behaviour in Australia's favourite bird, the superb fairy wren, also known as the blue wren. Every year, male wrens change their color from dull brown to a stunning combination of brilliant azure blue, with contrasting dark-blue and black plumage.

This annual color change makes them a useful study species for measuring the risk of being brightly colored, as the behaviour of the same individual bird can be compared while he is in different colors.

As part of this study, published in the Royal Society Journal Proceedings B, researchers snuck up on unsuspecting fairy-wrens. They then broadcast fairy-wren alarm calls from portable speakers, and observed the behaviour of the birds.

"When birds hear such alarm calls, it tells them there might be a predator nearby," says Alex. "Whether they ignore the alarm or flee to cover, and the amount of time taken to re-appear from cover, tells us how high they perceive their predation risk to be.

"We found that fairy-wrens were more cautious while they were bright blue: they fled more often in response to alarm calls, and took longer to re-emerge from hiding. They also spent more time in cover, and more time scanning their surroundings."

Alex's supervisor, Associate Professor Anne Peters said an interesting observation was that brown fairy-wrens appeared to take advantage of the risks faced by blue males.

Fairy-wrens go about in social groups, often made up of individuals in different plumage colors.

"When a blue male was nearby, fairy-wrens spent less time hiding in cover after fleeing in response to alarm calls, and devoted less time to keeping a look-out," Associate Professor Peters said.

"This could be because the dull brown wrens view blue males as a colorful decoy that reduces their own risk, or because blue males are more vigilant, allowing the brown wrens to drop their guard."

The study, which was done in collaboration with Professor Rob Magrath from the Australian National University (ANU), shows that fairy-wrens perceive themselves to be at higher risk when they display their bright blue plumage, and adjust their behaviour accordingly.

Story Source: Monash University. "The trouble with being a handsome bird." ScienceDaily. (accessed July 4, 2017).

Journal Reference:
Alexandra McQueen, Annalise C. Naimo, Niki Teunissen, Robert D. Magrath, Kaspar Delhey, Anne Peters. Bright birds are cautious: seasonally conspicuous plumage prompts risk avoidance by male superb fairy-wrens. Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1857): 20170446 DOI: 10.1098/rspb.2017.0446

Increased predation risk is considered a cost of having conspicuous colours, affecting the anti-predator behaviour of colourful animals. However, this is difficult to test, as individual factors often covary with colour and behaviour. We used alarm call playback and behavioural observations to assess whether individual birds adjust their response to risk according to their plumage colour. Male superb fairy-wrens (Malurus cyaneus) change from a dull brown to conspicuous blue plumage each year, allowing the behaviour of different coloured birds to be compared while controlling for within-individual effects. Because the timing of colour change varies among males, blue and brown birds can also be compared at the same time of year, controlling for seasonal effects on behaviour. While blue, fairy-wrens fled more often in response to alarm calls, and took longer to emerge from cover. Blue fairy-wrens also spent more time foraging in cover and being vigilant. Group members appeared to benefit from the presence of blue males, as they reduced their response to alarms, and allocated less time to sentinel behaviour when a blue male was close by. We suggest that fairy-wrens perceive themselves to be at a higher risk of predation while in conspicuous plumage and adjust their behaviour accordingly.
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  • Claudiu Constantin Nicolaescu
Fairy-wrens learn alarm calls of other species just by listening

Date: August 2, 2018
Source: Cell Press

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Superb fairy-wren (Malurus cyaneus).
Credit: © / Fotolia

Birds often eavesdrop on the alarm calls of other species, making it possible for them to take advantage of many eyes looking out for danger. Now, researchers reporting in Current Biology on August 2 have found that fairy-wrens can learn those unfamiliar calls -- which they liken to a foreign language -- even without ever seeing the bird that made the call or the predator that provoked it. Instead, the birds in their study learned to recognize new alarm calls by listening for unfamiliar sounds within a chorus of familiar alarm calls.
"Alarm calls warn of predators, but here the birds learnt the meaning of the call from the alarm calls of others without needing to see the predator," says Robert Magrath of the Australian National University in Canberra. "This means it is a type of 'social learning,' where individuals learn from others rather than through direct experience. In this case, it's even more indirect, because they only need to hear and not see the birds giving the familiar alarm calls. So theoretically they could learn with their eyes closed!"
Magrath's group had long been interested in bird alarm calls and eavesdropping among species. Their previous work showed that birds can learn to recognize other species' calls; it isn't always an innate ability. Their studies showed that fairy-wrens could learn to associate a novel alarm call with danger if they repeatedly saw a model predator at the time they heard the call.
Those studies showed the birds were learning by direct experience. But the research team -- also including Dominique Potvin and Chaminda Ratnayake from the Australian National University, and Andrew Radford from the University of Bristol, UK -- suspected that birds could also learn from other birds, by listening closely to their calls.
"It makes sense to learn from others when it is dangerous to learn through direct experience," Radford says. "The current experiment shows that they can," and through the novel process of making associations between different sounds.
The team trained birds in the absence of any predator by broadcasting unfamiliar sounds in combination with the alarm calls of other fairy-wrens and other bird species. At first, the birds didn't flee from the unfamiliar sounds. But after training, they often did flee to cover upon hearing the sounds. Their experiment showed the fairy-wrens also continued responding equally strongly in repeated tests over the course of a week.
It wasn't that the fairy-wrens had become warier in general. Rather, they had learned to associate new calls with known alarm calls, without ever seeing the caller or the reason for their call.
"The results were striking," Potvin says. "They show just how quickly social learning can occur in the wild through listening to alarm choruses, a tactic that's likely to come in handy given how hard it is to see predators and callers in many environments."
Social learning by whatever means can help to explain the widespread eavesdropping seen in nature, the researchers say. The new findings may also be relevant to conservation efforts.
Often, endangered species breed well in captivity only to be taken by predators soon after release. As such, there are now efforts to prepare birds for life in the wild by training them to recognize their predators prior to release. "We think it would also be helpful to train birds to recognize the alarm calls of other species," Magrath says. Their new study shows just how to go about it.
This research was supported by an Australian Research Council Discovery Grant.

Story Source:
Cell Press. "Fairy-wrens learn alarm calls of other species just by listening." ScienceDaily. (accessed August 3, 2018).

Journal Reference:
  1. Dominique A. Potvin, Chaminda P. Ratnayake, Andrew N. Radford, Robert D. Magrath. Birds Learn Socially to Recognize Heterospecific Alarm Calls by Acoustic Association. Current Biology, 2018; DOI: 10.1016/j.cub.2018.06.013
Animals in natural communities gain information from members of other species facing similar ecological challenges, including many vertebrates that recognize the alarm calls of heterospecifics vulnerable to the same predators. Learning is critical in explaining this widespread recognition, but there has been no test of the role of social learning in alarm-call recognition, despite the fact that it is predicted to be important in this context. We show experimentally that wild superb fairy-wrens, Malurus cyaneus, learn socially to recognize new alarm calls and can do so through the previously undemonstrated mechanism of acoustic-acoustic association of unfamiliar with known alarm calls. Birds were trained in the absence of any predator by broadcasting unfamiliar sounds, to which they did not originally flee, in combination with a chorus of conspecific and heterospecific aerial alarm calls (typically given to hawks in flight). The fairy-wrens responded to the new sounds after training, usually by fleeing to cover, and responded equally as strongly in repeated tests over a week. Control playbacks showed that the response was not due simply to greater wariness. Fairy-wrens therefore learnt to associate new calls with known alarm calls, without having to see the callers or a predator. This acoustic-acoustic association mechanism of social learning could result in the rapid spread of alarm-call recognition in natural communities, even when callers or predators are difficult to observe. Moreover, this mechanism offers potential for use in conservation by enhancing training of captive-bred individuals before release into the wild.

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Full Study:
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  • Claudiu Constantin Nicolaescu
Aussie birds turn down their thermostat to save energy in winter

by Western Sydney University

[Image: aussiebirdst.jpg]
Passeriformes - passerines. Credit: MathKnight, Creative Commons Attribution-Share Alike 4.0 International license

Research published in Biology Letters by scientists at Western Sydney University provides the first clear evidence that a species of perching bird (the passerines) can employ torpor—an energy-saving mechanism whereby the body temperature of an animal is temporarily reduced in a controlled way during resting.
In this new research, the authors used miniature radio-transmitters to record the skin temperature of these tiny eight-gram birds over several weeks during winter in woodland near Sydney. Skin temperature provided a close approximation of body temperature in such small animals. Remarkably, they showed these fairy-wrens allow their body temperature to decrease substantially during their nightly roosting phase. These periods of nocturnal torpor closely resemble the torpor that is well-known in some small mammals and in a few non-passerine bird groups like hummingbirds. This new evidence of regular use of torpor by a passerine bird is important for understanding the physiology and ecology of birds.
Birds are typically small and light, which helps them to fly and escape from predators but means they cannot carry a lot of fat and this presents a challenge during winter when food is hard to find. The use of torpor provides a very effective mechanism to reduce the amount of energy required for thermoregulation when resting during the night. Torpor could be an important strategy allowing small birds to cope with limited and fluctuating food supplies.
"Even in a relatively mild climate, superb fairy wrens benefit from the energy-savings that nocturnal torpor provides," said Dr. Christopher Turbill from the Hawkesbury Institute for the Environment at Western Sydney University.
"When roosting during the night, the bird can reduce its demand for energy by turning down its internal thermostat—reducing its core body temperature by nearly 15 degrees Celsius compared to during the daytime. We estimate this use of torpor saves the bird around 22% of the energy it would otherwise need," said Chris.
This study is the first to record torpor in a representative of the perching birds or passerines, an order that contains around half of all bird species. Previously, torpor was well-known among several non-passerine groups, most notably the hummingbirds and nightjars, whereas passerine birds were only known to use mild torpor when they faced starvation.
"This finding provides clear evidence that torpor is used on a daily basis by a small passerine bird, even in Australia's mild climate. Very few studies have measured the body temperature of wild passerine birds and our data suggest torpor might be more common than we thought," said Alex Romano, who recently graduated from his Masters of Research and led the research.
"The superb fairy wren has been used for decades as a model species to answer many important questions in behavioral ecology, so it is quite incredible that Alex still managed to discover something so basic yet profound about the species' fundamental biology," said Dr. Justin Welbergen, who was also part of the research team.
By significantly reducing their daily energy needs, scientists propose that small mammals and birds use torpor to enhance their chances of surviving through winter, and because energy-savings from torpor reduce the need for foraging, its use can also reduce the likelihood of being consumed by predators during the active period of the day.

Journal Reference:
Alex B. Romano et al. Nocturnal torpor by superb fairy-wrens: a key mechanism for reducing winter daily energy expenditure, Biology Letters (2019). DOI: 10.1098/rsbl.2019.0211

Many passerine birds are small and require a high mass-specific rate of resting energy expenditure, especially in the cold. The energetics of thermoregulation is, therefore, an important aspect of their ecology, yet few studies have quantified thermoregulatory patterns in wild passerines. We used miniature telemetry to record the skin temperature (Tskin) of free-living superb fairy-wrens (Malurus cyaneus, 8.6 g; n = 6 birds over N = 7–22 days) and determine the importance of controlled reductions in body temperature during resting to their winter energy budgets. Fairy-wrens routinely exhibited large daily fluctuations in Tskin between maxima of 41.9 ± 0.6°C and minima of 30.4 ± 0.7°C, with overall individual minima of 27.4 ± 1.1°C (maximum daily range: 14.7 ± 0.9°C). These results provide strong evidence of nocturnal torpor in this small passerine, which we calculated to provide a 42% reduction in resting metabolic rate at a Ta of 5°C compared to active-phase Tskin. A capacity for energy-saving torpor has important consequences for understanding the behaviour and life-history ecology of superb fairy-wrens. Moreover, our novel field data suggest that torpor could be more widespread and important than previously thought within passerines, the most diverse order of birds.
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