Tropical Topics An interpretive newsletter for the tourism industry

Bird body language No. 65 March 2001 Why the flashy males? Notes from the We humans flout the rules of nature. While it is generally human females who go for colours and ornamentation, in most other species, if there is a difference Editor between the sexes, it is invariably the males which dress up. Tropical Topics no. 56 looked at This is particularly true in the case of display, his song and/or his bower. calls and songs. This issue *. The most spectacular, such as The most proficient displays and the looks at visual signals. Whereas the birds of paradise, peacocks and best bowers usually belong to the many mammals, reptiles and other pheasants, go to incredible older and most experienced birds — other use scent for lengths to impress the opposite sex proof that they are tough survivors communication, birds rely heavily with elaborate, colourful and with worthy genes. Good plumage is a energetic displays. Male bowerbirds clear indication of good health in a on visual and audible signals. concentrate their efforts on producing bird, which may therefore have an Although we cannot hear or see wonderfully constructed and inherited, and inheritable, resistance to as much as birds (see page 7), on decorated courting platforms. diseases. It also shows that the bird the whole this makes it a lot Why do they need to work so hard? has access to good food sources — easier for us to understand, or at an important attribute in males which least, guess their intentions. One reason is that most male birds will be relied on to feed the young. Indeed, their animated antics cannot mate unless the female accepts invite us to try to understand their them. The few with penises (3 percent The desire of females for certain male body language. of all birds, including emus, attributes can lead, over evolutionary cassowaries and all waterfowl) can time, to those characteristics becoming force their attentions but the vast increasing exaggerated. If males with Acknowledgements majority of male birds must persuade flashy plumage get to mate with more Much of the information, and the females to co-operate in the brief females, then it is to the advantage of some of the illustrations, in this balancing act which constitutes a female to produce males with issue of Tropical Topics came mating in birds — and females demand similarly flashy plumage so that her from various issues of the high standards of courtship before genes have the best chance of being Interpretive Birding Bulletin. they will participate. perpetuated. Then each time the males Published six times a year, this with the longest tails, for example, are 16-page bulletin is devoted to This is not just a case of female selected by the females, the gene for whimsy. A male is able to produce long tails is passed on and reinforced. observations of bird behaviour. It abundant sperm and mate many times, As a result, some males, such as the is available on subscription — but a female has invested her energies lyrebird, have ended up with tails see Bookshelf on page 8 for in just a few eggs. She wants to make which must surely make them an easy details. sure she chooses the best father for target for predators. On the other her precious offspring. She wants hand, this provides further proof of Please note good genes and, from those fathers the owner's fitness. If he that you are welcome to photocopy which help to raise the brood, has managed to Tropical Topics. However, if the a useful provider. survive with this text is reproduced separately it must handicap then he is not be altered and must The female therefore obviously a suitable acknowledge the Environmental judges the fitness of a candidate for passing Protection Agency as the source. male by traits such as the on his genes. There Illustrations must not be reused condition of his plumage, are good reasons separately without permission. the standard of his why female birds Please contact the editor (details on put their mates to the back page) if in doubt. *For a notable the test. exception see page 5. Bowers are designed for courtship Show-offs Displays staged by birds can convey a number of messages. The same routine may be used for courtship or conflict, depending on the situation. It can be used as a greeting, to attract a mate, to reinforce a pair-bond, to bluff, to convey aggression or submission to rivals and/or proclaim ownership of a territory. Often it settles disputes without violence. Courting Multi-purpose facial plumes Our Australian birds of paradise put on quite a show at mating Feathers on heads and faces, can be time. The male riflebird stands on a display perch, flares out the erected by many birds to signal status, iridescent blue-green triangular bib on his chest and fans out his territorial threats, general aggression wings, arching them in a circle around his head. If a female — or attraction. appears to show interest he gets very excited, dancing animatedly on his perch and beating his arched wings A ‘crestfallen’ person is a rhythmically and noisily. His head thrown back, his open mouth dejected one. Similarly the reveals a bright yellow interior, contrasting with his velvety height of a cockatoo’s black and iridescent plumage. crest is probably a good indication of its level of The kori bustard may not have such colourful plumage, but makes up for it in excitement and alertness effort. Throwing back his head he droops his wings, erects his tail, fans out his while a lowered crest may neck feathers and, booming and roaring, sways from side to side. Like many of signal submission. Some the greatest show-offs, he contributes nothing to child care. birds without noticeable crests, such as satin and Instead of relying entirely on plumage for display, male bowerbirds construct related flycatchers, can raise courtship areas. Some fairy-wrens say it with flowers — the male will pluck a petal the feathers on their crowns and present it to the lady of his choice. The colour selected varies with species. during confrontations. A number of birds which form long-term pair bonds, Willie use dance together throughout the year to reinforce their eyebrows in those bonds. Cranes are famous throughout the territorial disputes. world for their dances and our brolgas and sarus Diving at a rival, and cranes are no exception. Dancing back and forth, the chattering crossly, an males and females shake their spread-out wings, aggressor expands and bow deeply, and from time to time spring up to three fluffs up the white feathers. metres into the air. To indicate submission, the loser is able to withdraw its Male pelicans march around in groups behind a female, gaping open their eyebrow completely. Both impressive bills and swinging their heads from side to side as they threaten each male and female approach other. Males and females both snap their bills open and shut to make the courtship with raised colourful pouch wobble and indulge in some high-stepping. eyebrows.

Birds of prey, such as ospreys and peregrine falcons court each other with Fluffing out feathers can make a spectacular aerial displays during which they swoop, plunge and tumble bird seem a more daunting opponent. sometimes wheeling around with interlocked talons. Perhaps this allows them to The male rufous whistler fluffs out his assess each others’ ability to catch prey for the young. white throat feathers during territorial disputes. A number of honeyeaters Raising the white flag signal with facial plumes. When some To avoid being picked on, many birds interfering researchers will signal their unwillingness to fight. removed these plumes They may sleek down their plumage, from New Holland withdraw their head and avert their bill honeyeaters (right), those — their main weapon. Some species individual birds ‘lost face’, have stylised signals. A dusky their position in the group moorhen, defeated in the course of a deteriorating. confrontation, turns its back and flips This patch is taken up its tail to display the white Birds regularly advertise their Lewin’s honeyeaters feathers on either side. If are able to erect the territories with song but some crescent-shaped tufts of two moorhens decide to reinforce this with displays. Duetting settle a dispute loudly together, magpie-larks open feathers on the sides of their peacefully they may heads. These tufts may indicate their wings, their black and white dominance, and allow less both make use of this plumage making a striking display of conciliatory gesture. ownership. dominant birds to back away from conflict, over food sources, for example, without injury. Purple swamp-hens flick their tails. Kookaburras have stand-offs with Since juveniles do so more often, this neighbouring kookaburra groups at is thought to signal their low status Great, spotted and western bowerbirds common boundaries. Individuals from are fairly dull birds but the males have and thus defuse the tendency of more each group may take it in turns to dominant birds to challenge them. On invade, and be chased from, the an unexpected attraction — a lilac the other hand, tail-flicking may simply bunch of feathers on the back of their neighbours’ patch. Laughing necks which can be raised and flashed indicate excitement or act as a signal to kookaburras ritualise this by flying to a predator, letting it know that it has and fro across the boundary in unison, when females venture near their been spotted and shouldn’t waste any bowers. Confident male fairy wrens passing each other in mid air rather like make the most of their striking blue more time stalking this particular trapeze artists. victim. plumage by flaring out the blue feather fans on their cheeks during courtship.

2 Dusky moorhen and magpie-lark illustrations courtesy Interpretive Birding Bulletin Out and about Tiny, furred insectivorous Sassafras trees (Doryphora bats sometimes turn up in aromatica) usually scatter their fruit in houses at this time of year March. This tree is normally found in clinging to washing or mature, densely-shaded rainforest but, curtains or even crawling James Cook University student, Mary unusually for deep rainforest trees, it across the floor. These are Gandini, with assistance from Marine relies on wind to scatter its seeds. usually northern mastiff Park volunteers and rangers as well as (freetail) bats — not ‘baby flying other JCU students and staff, have The trees produce fragile foxes’ as many people assume. Flying produced a plant list for Low Isles, off white flowers. foxes are much bigger, use their eyes Port Douglas. Following to find their way around and feed on pollination, the nectar and fruit. Insectivorous bats are A year of collecting, identifying, base of the flower very much smaller, navigate using pressing and photographing resulted grows into a woody sonar (echo-location) and feed on in a list totalling185 plants. This almost container which small insects like mosquitoes. Look doubled the number previously eventually splits to into the evening sky as it is getting recorded. Of the plants listed, 135 were release numerous plumed fruit. Each dark and you will see them flitting native plants and 50 were exotic ones bearing a single seed, these are around. which had either been deliberately designed to blow on the wind. Clumps planted by lighthouse staff or were of these brown furry fruit can often be At this time of year the babies are invasive weedy species. Numerous seen beneath a big sassafras tree. beginning to , so it may be these seedlings and saplings had germinated inexperienced ones which blunder into from the droppings of pied imperial- our houses — or the wet weather may pigeons which nest on Woody disorient them and cause them to lose Isle, but few of these make a essential body warmth. If you find one permanent contribution which seems uninjured, wrap it loosely because many die off in a tea-towel and hang this from a during the dry coat-hanger in a window or balcony season. Some items, past their 'use- where the bat will be able to take off when it is ready. Keep an eye on it, This list is by date', have been removed however, and if it is unable to fly off available from from the web version of the confidently take it to your local the Port Douglas QPWS office, Ph: Wildlife Care Group. The office of the (07) 4099 4709. newsletter. Far North Rescue Association is at Unit 4/ 114 Hoare St, Cairns; Ph: 4053 4467.

A report on crown-of-thorns starfish has just been published. Detailed fine-scale surveys, conducted from 1999 to 2000, found large numbers of juvenile crown-of-thorns starfish on the 19 reefs surveyed in the Cairns and Central sections of the GBR. Record numbers of juveniles (aged 1) were found in the 1998/99 season (see graph). These have now matured and have caused considerable damage by eating large areas of hard coral. The finding of more juveniles in large numbers in the 1999/2000 season is of concern, particularly as the sub-adults and juveniles on badly damaged reefs were found feeding on small recently settled new Beach almond (Terminalia catappa) colonies. This could have a serious impact on the ability of reefs to recover. trees are a common sight along tropical foreshores. Their branches The report’s findings suggest that crown-of-thorns starfish outbreaks are grow horizontally with large, oval becoming more frequent, high densities having been found on the same reefs leaves which turn an autumnal red in the dry season. At this time of year, 3.5 within five years. Nine core reefs are to be resurveyed over the next three however, they produce large numbers months. of green fruits, tapered at each end. 3.0 These are attractive to flying foxes as 2.5 The report, Crown-of-thorns starfish well as to rodents and sand crabs (Acanthaster planci) in the central which eat them when they fall. Below the fleshy exterior is a fibrous layer 2.0 Great Barrier Reef region. Results of fine-scale surveys conducted in 1999- within which is a brown almond- shaped seed. These seeds are edible 1.5 2000 by U. Engelhardt, et al., is published as Technical Report No. 32 and produce an oil when squeezed. 1.0 by CRC Reef Research Centre. It is These fruits are frequently seen on the

Udo Engelhardt available from the CRC, c/- James Cook 0.5 University, Townsville, QLD 4811; Ph beach, often with the (07) 4781 4976 and should be available fibrous layer Mean densities per 50x5m transect attached. They 0.0 soon from the Queensland Parks and 1994/95 1995/96 1996/97 1997/98 1998/99 1999/2000 Wildlife Service office at 10-12 can remain afloat McLeod St, Cairns, QLD 4870; Ph: (07) for two years or Mean densities of juvenile COTS (aged 1) across more. all survey reefs over a six-year period. 4046 6600.

3 Colour codes and patterns Colours and patterns are used to define the species of a bird, to convey messages regarding sexual identity, status, mood, territory and danger as well as to attract mates. Dressed to impress The males which put most effort into producing visual attractions, such as the birds of paradise, lyrebirds and bowerbirds, are invariably promiscuous flirts. The males take no part in building nests, incubating eggs or caring for nestlings. They devote all their energies Moody colours to being attractive and mating with as many females as possible — The red comb of a genetic flashiness is their only legacy to future generations. comb-crested jacana changes colour according However, this arrangement can only work where food is plentiful to the situation. When the and close enough for the female to raise a brood on her own. bird is in relaxed or This is a comparatively rare situation so in most cases both submissive mood the comb is parents contribute to childcare. About ninety percent of birds a pale yellow. When it is are considered monogamous, in that the pair stay together throughout the breeding excited or aggressive a rush of season. At least that is the theory. In fact, DNA sampling has shown that it is not blood colours it a bright red. The uncommon for the females of many species to mate with other males and that the eggs in change can be instant and is probably one nest frequently have many different involuntary, conveying information about fathers. This may explain the tendency for the bird’s mood and motivation. Both many monogamous males to be flashier male and female jacanas defend territories, than the females — the flashiest are often so both have this feature, ready to signal chosen for these ‘adulterous’ affairs and defence capability, or willingness to mate. get to father more youngsters than the less attractive males. Nonetheless, the duller male female The facial skin around the eyes males get to father at least some of the of male figbirds is normally a brood so are still willing to put in the hard dull red or buff but glows red Interpretive Birding Bulletin work looking after them. when the bird is excited. The males and females of many bird Differences between male and female can species appear identical*. These birds rely be very subtle. Some bronze-cuckoos primarily on songs and/or behaviour to males have red eye-rings while the Role reversal female’s eye-rings are buff or cream in We are so accustomed to reveal sexual identity and may indulge in males with the brighter quite elaborate displays (see page 2). colour. The male sulphur-crested cockatoo has a darker eye than the plumage that uninformed Those birds which pair for life (and are birdwatchers are regularly normally relatively long-lived) are usually female. The head markings of magpie larks (above) are slightly different. confused by the male and alike. female eclectus parrots, of Cape York. The male is mostly green while the female is a Sexual camouflage vivid red and bright blue. The Juvenile males, of species in which there is a plumage difference reason is thought to be the between male and female birds, often resemble the females. shortage of suitable nesting Alternatively, juveniles have a uniform of their own. It is thought hollows. Females, when they that this allows them to mature in peace without provoking the acquire a good hollow, become extremely aggression of mature birds which might mistake them for rivals. Juvenile metallic territorial, spending long periods, even Only when they are mature enough to actually become a threat, starlings have outside the nesting season, hanging does their plumage change to reflect their changed status. streaked breasts, unlike about the entrance. It is thought that their the glossy black of the bright colours help them to advertise to adults. rival females that ‘this spot is taken’. Temporary costume changes Some birds put on their courting plumage only at breeding time, thereby reducing the period Camouflage during which their striking looks make them more vulnerable to danger. Some birds simply look The primary function of many birds’ brighter, in new feather suits. Others grow special feathers. Egrets of many species develop plumage is to camouflage them. elaborate plumes on their necks, breasts and backs. Their eyes, , facial skin, legs and feet Brightly coloured males often have may also change colour. These changes signal the readiness of the bird to breed. partners with dull plumage, which conceals them well while sitting on Many of the dull brown migratory waders which visit us the nest. Birds, such as waders, which during summer are transformed when they return to their feed in the open, and nocturnal birds Dusky moorhen, magpie-lark and brush-turkey (retracted wattle) illustrations courtesy northern hemisphere nesting grounds. We don’t see the red are also often cryptically coloured. A neck for which the red-necked stint (left) is named, except in some frogmouth is almost impossible to see birds departing in March and April which have already when standing with its pointed achieved a deep salmon colour on their faces and necks. skywards, perfectly imitating a broken stump. Some patterns, such as eye Most male fairy-wrens lose their bright plumage at the end stripes, may serve to break up the of the breeding season, becoming duller, but safer. Some outline of a bird and conceal its eyes. adopt breeding plumage earlier than others and are thought to be the ones which get the most mates, being obviously fit Despite its bright colours the double- and healthy enough to be the first of the season with the eyed fig parrot can be incredibly necessary resources to grow the right clothes. difficult to find, even if it is calling loudly. Its bright green blends well The bills and pouches of courting pelicans become dramatically more with tropical foliage, while the colourful. The pouch skin at the neck end becomes bright yellow and red and blue patches can the front half bright pink to red with a dark blue stripe running along be mistaken for red the length. The upper bill becomes partly blue. This colour fades by the leaves or flowers and time the pair has begun to incubate the eggs. glimpses of sky.

4 *The fairly recent discovery that birds can see UV light means that there may be more to the significance of colour than meets our eyes (see p7). Badges Badges are used by many birds to advertise fitness and status. These plumage signals help to save energy and reduce potentially Badges of convenience damaging conflict between birds competing over food, territory and Some birds can choose to display or hide mates, while helping the females to make an informed choice. their badges according to situation or season. Male house sparrows (left) have black bibs which range in size. The larger the bib, the higher the status of the owner — and the more The bright yellow wattle of an females willing to mate with him. Researchers, curious to know why Australian brush-turkey all males do not grow large bibs, implanted some with hangs down from its red throat testosterone. The bibs of these males grew larger and they sang and displayed like a dangling fleshy necklace. more. However, tests showed that they also suffered very high levels of stress Like so many decorations, the male’s and were unlikely to survive for long. It seems that only the very fit birds are wattle is intended to both attract females able to cope with the high testosterone levels needed to maintain the high status. and to warn off other males; its size is an Females are therefore choosing well when they pick the large bibbed males indication of worthiness. because this is a true indication that they are the fittest. However, if a stronger male turns up, a bird is However, it seems that this fitness may depend on environment rather than genes. able to avoid provoking his British scientists put nestlings which had been fathered by small bibbed sparrow males rival and to back away from a into nests of large bibbed males, and vice versa and discovered that their bib sizes potentially damaging conflict eventually developed to resemble those of the foster, not the biological, fathers. It was by suddenly retracting his suggested that parental care determined the size of the bib — if, for example, large-bibbed wattle. fathers were good at keeping the nests free from debilitating parasites and at providing good food. Male frigatebirds have a patch of naked red skin on their An adolescent male yellow-bellied sunbird develops a throats which is normally an black line on his breast, which eventually grows into inconspicuous shrivelled patch of the familiar metallic blue-black bib. This allows the skin. At breeding time, however, females to know which are the mature males. Possibly they blow it up with air to create a the quality of the bib also conveys status. Sunbird large scarlet balloon which attracts the males have a habit of roving around in noisy gangs females. but from time to time they all freeze silently with their beaks pointing skywards. Perhaps they are showing off the quality of their bibs. Dusky moorhens have a red ‘shield’ on the front of their faces, the size and brightness of which are influential in determining the Fashion-conscious finches outcome in stand-offs between rival birds Studies of zebra finches have shown that females prefer (both male and female) disputing territorial those males in which the barring pattern of the throat boundaries. and breast is even. It seems that symmetry in this pattern indicates good genes and a healthy start in life. This preference may not be confined to birds. Researchers have discovered that humans are more attracted to members of the opposite sex with the most symmetrical features.

Curiously, female zebra finches are attracted to unnatural features. It appears that captive females are influenced by the colours of leg bands on prospective mates, Alarm patterns preferring red ones. Interestingly, they were more attracted to symmetrical Wing markings can communicate danger, arrangements of the coloured bands than to asymmetrical combinations of the same particularly in birds which do not use colours. alarm calls. Researchers in Europe, trying to minimise crop damage from wood In another experiment, researchers attached white, red and green feathered crests to pigeons, experimented with different both male and female zebra finches and long-tailed finches. The females of both decoys and discovered that while those species approved of the revamp and were strongly attracted to the males with white with open wings, but without wing bar crests. Male long-tailed finches also preferred white crests on their females, but male markings, had little effect, decoys with zebra finches were more conservative, rejecting all females who had adopted the new exaggerated wing bars deterred many crest fashion. birds from landing. Presumably the sight of the wing bar, shown as the pigeon takes off, suggests to nearby pigeons Nestling signals that this is an unsafe place to be. The interior of nestlings’ mouths are often colourful. This probably acts as an incentive, and provides a target, for the feeding parent. Canary parents have been shown to give Flocking waders tend to have white ‘flash priority to those chicks whose mouths have flushed reddest. This is marks’ on their tails, wings and rumps thought to happen when blood rushes from an empty stomach to the which are visible as they take off. Thismay mouth, but cannot happen if the nestling’s stomach is full. The quickly signal danger and reddest mouth is therefore the hungriest. encourage all birds to fly off A study of 125 different finches found that the nestlings of together, co- each species had unique mouth markings. This may have ordinating their evolved to prevent parasitic birds from laying their eggs flight as they in others’ nests — which might be why many cuckoo wheel in close nestlings quickly eject their hosts’ eggs and offspring, formation. before the parents have a chance to spot the difference. Some cuckoos have cleverly managed to imitate the mouth colour of the species they parasitise.

5 Questions & Answers Facts and stats Q Do flatback turtles nest at certain Female European chaffinches have been stages of the moon? both male and painted with pink breast feathers, to female reproductive look like the males. These birds usually A No and, to a certain extent, yes. tissue may be present. became dominant over other females This is because the moon affects the When a female becomes a male, the and even over some males. tides and it is possible for a very low ovarian tissue shrinks, while the male tide to prevent turtles from reaching sperm tissue spreads. The change Male American red-winged blackbirds the nesting beaches, by exposing may take a few weeks. In barramundi, have been shown to lose their territory if reefs and other nearshore following the first spawning season, the red patches on their wings are obstructions which form a barrier. eggs begin to develop in the male coloured black. However, their mates However, if there is beach access gonads as the fish changes from stood by them and were unaffected by they will nest, no matter what the male to female. In other fishes, both such a superficial change! moon or the tide is doing. Turtle male and female reproductive organs nesting is often associated with the are present. The functioning section Experimenters have used long-tailed full moon because that is when can be switched off and the inactive whydahs (widow birds) in Africa to prove people are most likely to see them — section switched on. This change is that females are influenced by plumage. but this does not mean they are not more rapid, taking just a few days, They cut off half the lengths of the tails nesting during the dark of the moon. and allows the fish to switch back of some males and added the extra In addition, it is not unusual for again. plumage to the tails of other males, and flatback turtles to nest during cooler left some alone. The experiment showed daylight hours. In reef fishes, the trigger for the that size does indeed matter to the female change seems to be controlled by whydah, since they showed a definite The flatback turtle breeds only in social conditions, related to a change preference for mating with the males . Like other sea turtles, it in the composition of the pair or with the artificially elongated tails. concentrates its nesting on a few group of fishes. The male, in a harem, mainland beaches and on cays and is thought to keep his females Experiments have shown that models islands. The breeding season extends feminine by bullying them at regular of predatory were more likely from October to January, a nesting intervals. When he is removed the to be mobbed by flycatchers if they female laying about 50 billiard-ball- largest female then becomes a male. had eye-stripes but that if the stripe sized eggs in a clutch and dropping If the dominant female in a group of was put in a different position, such as them into a pit which she has anemonefishes disappears, the male the breast, the mobbing decreased excavated in the beach. The baby becomes a female and the largest markedly. It is thought that eye-stripes turtles emerge from the nest between immature juvenile becomes a male. In on birds may help them to line up prey, December and March, with most large groups a certain ratio of males using them as sight-lines. Certainly, it hatching during February. Their to females is kept constant so if three seems that they appear predominantly carapaces (shells) are then about 5.5- males are removed, three females on birds which feed on living prey. It 6.5cm long. become males. In some pairs, a has been suggested that the eye-lines ‘widowed’ individual may be able to on herons may be angled to allow for Q How exactly do fish change sex? change sex to form a pair with the the distortion effect of water. next unattached individual (s)he A Over 350 fish species have some finds. Ospreys have been observed using a ability to change sex. These include particular flying pattern, along with many coral reef fishes such as Most fishes fertilise their eggs special calls, to advertise to other ospreys wrasses, parrotfishes, damselfishes, externally. Normally the male either that they have found a good source of groupers and some gobies as well as releases sperm over eggs laid in a schooling fish. Ravens and other birds barramundi. Most change from female nest, or both partners release eggs have also been known to communicate, to male, some from male to female, and sperm together in the water. somehow, a source of food. Perhaps if all some function as both male and birds living nearby (which may be closely female at the same time and others A good article on this is Changing related) always share their finds, all can switch back and forth. Sex by Philip L. Munday in Nature stand to benefit in the long run. Australia Vol 26 No 11 Summer In those fishes which change sex, 2000-2001 The shapes of the eyes and their position on the head vary according to the needs of the particular bird species. Most have eyes on the sides of the head so they can keep a sharp Tourist talk lookout for danger but hunting birds, such as owls and raptors, have eyes on the front of their faces. This allows ENGLISH GERMAN JAPANESE the fields of vision from both eyes to display Schaustellung hyogen overlap and gives these birds better plumage Federkleid umou depth perception. When they need to judge distances, birds often bob their ultra-violet ultraviolet shigaisen heads, which gives them different, polygamy Mehrehe ipputasai comparable views, in relation to the genes Gene idenshi background. badge Rangkennzeichen shirushi When walking, many birds, such as bib Latz yodare kake pigeons, appear to be nodding their heads courtship Balzen kyuai backwards and forwards. Actually they are keeping their heads in one place for territory Revier nawabari brief periods of time while their bodies crest Schopf, Haube kan u catch up. This allows them to see better.

6 Bird vision Birds have very good eyesight — some birds of prey are able to see about two and a half times better than we can — and they have exceedingly quick responses. They also have excellent colour vision. Tricks of the light UV — seeing another The colours of feathers are created in a number of different dimension ways. Some come from pigments. The most common is Among mammals, we are unusual in melanin, the pigment which darkens our skin in the sun. that we can see colour. Birds, A budgie’s feet This creates the dark colours — black, brown and yellow- however, can see even more than we can glow and the orange. Reds and oranges are created by carotenoid — ultra-violet (UV) light. This is thanks to blue patches on pigments, derived from food such as crustaceans (which an extra type of photoreceptor (cone) cell its cheeks and obtain them from blue-green algae) but parrots create which is missing from our eyes and which its rump yellow, orange and red from another pigment, porphyrin. is tuned to these particularly low fluoresce with Red is a particularly ‘expensive’ colour to produce so if a wavelengths of light. Studies are now UV light. male bird’s red plumage is especially bright this indicates showing that many, if not most, birds have that he has access to good food sources and, perhaps, that a UV component to their plumage. he is genetically good at assimilating the red from his food. This relatively recent discovery has added an unexpected Other colours are structural. Tiny air bubbles in the feather dimension to our theories of how birds use and react to interfere with short colour. For example, birds of some species, in which males wavelengths of light — Light is made up of different and females appear identical to us, actually look quite UV and blue — and wavelengths. A leaf looks different from each other when the UV component of their reflect them back to the green to us because the long plumage is viewed. Experiments in which the UV-reflecting eye. (Long wavelengths wavelengths — the yellow, feathers were covered with sunblock showed that “females such as red and yellow orange and red ones — are overwhelmingly preferred to associate with untreated males are absorbed by the absorbed by the surface and over treated males”*, suggesting that this is yet another feather and made the shorter green wavelength is aspect of the competitive plumage-war between different invisible.) reflected off to reach our eyes. males. Indeed, these feathers are most often found in the parts of the bird, around the head, front and rump, which Chemical and structural sources of colour can be combined are normally involved in visual display. in feathers. Green is created by a combination of yellow pigment and blue, light-scattering, structures. UV light perception may have a number of different Iridescence is created structurally. Microscopic melanin functions. Birds which feed particles, arranged on flattened filaments within the feather, on flowers may use it in split light, creating the same effect as an oil film on water. the same way as bees do, Reflected light waves interfere with each other producing a to perceive UV ‘nectar range of colours which may change, depending on the angle guides’ on the petals. King parrots of view. These structural adaptations make these feathers Invisible to our eyes, these reflect UV unsuitable for flight so iridescence is found only on non- lead them to the nectar source. flight feathers. Fruits with waxy coatings appear different to birds with UV perception — black ones can look blueish and white ones may glow. Bluff and distraction European kestrels are able to find an Birds’ displays are not always directed at others of the same species, or even easy meal by following urine scent trails at other birds. Some are intended for predators. left by voles which, unbeknownst to these colour-blind mammals, glow When predators come too close to a bird’s eggs or young, it will often create a brightly with UV-reflecting light, distraction by making itself conspicuous. Ground indicating ‘dinner this way’ to the nesting birds are experts at the ‘broken wing’ raptor. On the other hand, some routine. The red-capped plover (left), which which have evolved nests in a vulnerable shoreline position, can poisons and bad tastes to make often be seen putting on a very conspicuous themselves unpalatable, use UV, show, dragging its wing, limping and flapping until it instead of, or along with, bright ‘visible’ has drawn the predator to a safe distance colours, to advertise this feature. whereupon it gives up the pretence and off. Birds may also use UV light, and Another distraction strategy is the ‘rodent-run’ used by fairy-wrens and willie- polarized light — also visible to them — wagtails among others, where the parent bird drops to the ground below their to navigate. This allows them to locate nest, crouches down and scuttles along making an alarm call. Resembling a rat the sun’s position on a cloudy day. or mouse, it may be successful in engaging the attention of the predator. As ever, we need to be cautious with If the broken wing routine fails, some birds will attempt to frighten off their our interpretation of behaviour. enemies with intimidation. The bush curlew spreads its wings out wide and While signals transmitted and received raises its head, presenting quite a daunting adversary. in the UV wavelength may simply enhance other colour codes, it is always Mobbing possible that we are judging bird Some birds mob predators very much bigger than themselves. The feisty willie behaviour without being able to see the is one of the most persistent of these, fearlessly attacking kookaburras, whole picture. crows, cats and even peregrine falcons. Some years ago, when a peregrine falcon was in the habit of using the top of the Cairns Base Hospital as a perch, *Jim Davis. Ultraviolet Vision in Birds: a particularly bold willie wagtail regularly flew all the way to the top of this five- Hidden Perception. Interpretive Birding storey building to harass the peregrine. Acknowledgements to Rupert Russell. Bulletin Vol. 2 No. 2 August/Sept. 1998.

7 Bookshelf Interpretive Birding Bulletin Reader’s Digest Complete Book of Nature Australia Vol 26 No 9 Winter 2000 Dr. Wm. James Davis (editor) Australian Birds Badges of fatherly pride Available from PO Box 362, Toowong, Reader’s Digest (1993) A report of the cross-fostering of sparrow QLD 4066 Much of relevance on bird behaviour. nestlings experiment. Subscription: $30.00 for one year (6 issues) The editor is keenly interested in all aspects Birds of Queensland’s Wet Tropics and Nature Australia Vol 25 No 2 Winter 1997 of bird behaviour and synthesises a great Great Barrier Reef Signals of the flesh deal of information from numerous scientific Lloyd Nielsen Natalie J. Demong and Stephen T. Emlen papers into this readable and interesting Gerard Industries Proprietary Limited (1996) Jacanas and their fleshy, colour-changing publication. A useful field guide to local species, with an 'shields'. original and useful layout. The Life of Birds Wingspan Vol 10 No 2 June 2000 David Attenborough Nature Australia Vol 24 No 11 Summer 1994 That hollow feeling … BBC (1998) Dressed to impress Sarah Legge and Rob Heinsohn The book of the TV series, chapters 6 and Mark A. Elgar & Michael J.L. Magrath An article on eclectus parrots. 7 are the most relevant to the topic of visual This article looks at why females prefer well- communication. The video, also available, endowed males. Geo Australasia Vol 21 No 1March 1999 is a good chance to watch the birds in action. Brolgas of the Dreamtime Nature Australia Vol 26 No 3 Summer 1998 Graham Pizzey Bird Behaviour Sexy sparrows Robert Burton A report on the experiment on sparrow bibs Nature Australia Vol 26 No 4 Autumn 1999 Granada (1985) and testosterone. A sight for UV eyes Interesting on vision/ visual communication. Blue tits and UV vision.

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