Tropical Topics A n i n t e r p r e t i v e n e w s l e t t e r f o r t h e t o u r i s m i n d u s t r y
Birds breeding No. 52 January 1999 Helpful offspring Notes from the Kookaburras like to chorus, family groups of up to a dozen together producing a cacophony which proclaims their Editor territory. The more birds, the louder the chorus and the The excellent David Attenborough stronger their territorial claim. Kookaburras therefore television series, Life of Birds, (ABC benefit from living in large families. 7.30pm on Sundays) has recently been focussing our attention on the varied Most birds drive their offspring from There are several and often entertaining behaviour of their territories as soon as they are theories and no birds. This issue of Tropical Topics independent, but young kookaburras doubt some are takes a look at some of our local birds continue to live at home for about four valid for some and, in particular, their breeding years. During this time their parents species and some behaviour. put them to good use; young laughing for others. Possibly a kookaburras perform about a third of young helper: Birds are a bit like tropical reef fish. incubation and brooding duties for the • unable to breed and pass Unlike so many other animals, they next generation and supply the on its own genes, does the are colourful, visible, act out their nestlings with over half of their food. next best thing by promoting the lives largely in full view — and move family genes. through space with enviable ease. Kookaburras are not the only birds to • having mated with the breeding They invite our interest and, as breed co-operatively. In fact, child female is (or believes he is) the researchers learn more about them, labour is a feature of least 80 father**. (Females may deliberately they become ever more fascinating. Australian species* including forest recruit helpers by mating with them.) Bird watching can be simply about and buff-breasted paradise- • helps in exchange for ‘pocketmoney’ identification — ticking names of kingfishers, bee-eaters, a number of — the right to remain, and feed, at species on lists — or it can be about honeyeaters, particularly the miners, home. understanding what the birds are fairy-wrens, thornbills, robins, • learns vital childrearing skills. doing, which in many ways is much woodswallows and butcherbirds, to • hangs on, hoping one day to inherit more worthwhile. mention only some. the estate. • finds safety in numbers — more As usual there are many more aspects Why do these young birds hang lookouts give more warning of to this topic than room in the around with their parents instead of predators — and more feeders help to newsletter. Look out for more on bird setting up homes of their own? keep the nestlings quiet. behaviour in future issues. Breeding may well be limited by food • having helped raise a brood can then scarcity, particularly where there is no recruit them into its gang and, with I would like to thank Steve Garnett, seasonal increase (as happens during strong numbers, move out to establish DEH, and Elinor Scambler for their a northern hemisphere spring) to fuel a its own territory. help with this issue. sudden population growth — and more beaks are needed to gather it. Whatever the reason, co-operative Please note breeding seems to be a particularly that you are welcome to photocopy Even if the young birds cannot breed Australian phenomenon — 85 percent Tropical Topics. However, if the by themselves how are they of all bird species which breed co- text is reproduced separately it must persuaded (every human parent with operatively are found here — and may not be altered and must adolescent children may well want to well be a response to Australian acknowledge the Environmental know) to help with domestic chores? conditions. Protection Agency as the source. Illustrations must not be reused *Details vary between species. Some pairs are capable of raising a brood without without permission. Please contact help, but others invariably fail if they try. Some require only a few helpers, while the editor (details on the back page) others may have 20 or more. if in doubt. **Although helpers are often closely related to the breeding pair and nestlings, sometimes they are not (see Promiscuous fairy-wrens, p7). Bowers Mimics Bowers are not nests but display areas, built by male bowerbirds to attract All the Wet Tropics male females for mating. Females choose their mates after carefully inspecting the bowerbirds are known to mimic structure and decorations of each bower (rare items gain bonus points) as well other birds, usually as part of as the male’s plumage, his display and his vocal repertoire. Males with the best their courtship display. Male displays get to mate with the most females — in any population only a few tooth-billed bowerbirds (right) experienced males, with the most impressive bowers, may actually father the can copy the songs of more young. This creates much competition with males actively destroying the bowers than 20 other birds. From September to of rivals and stealing trophies. This forces the victims to spend more time on February each year they enliven the rebuilding and less on seducing females. Following his conquest, the male forest in the vicinity of their stages, bowerbird takes no further interest in the female and his offspring. In contrast giving an impression of countless to their mates’ elaborate structures, the females build rather ordinary cup or species of birds in full song. The males saucer nests made from twigs. sing for much of the day and it is thought that the mimicry component is Tooth-billed bowerbirds’ bowers are The great bowerbird and the satin used specifically to attract females. the simplest. The male clears an area bowerbird build avenue bowers. Thin However, the loud songs also seem to one to three metres in diameter, sticks are neatly arranged in an upright function as an advertisement of returning to exactly the same patch of position, forming two parallel walls, territories to other males since a bird forest floor each season. He then looking almost like a couple of old- will stop now and then to listen for its decorates his stage with fresh leaves, fashioned brooms sticking out of the neighbours. If an adjacent rival is not pale side up, having snipped them off ground with a narrow passage heard, the bird may then mount a quick with his double-notched bill. Each day between. Decorations are mainly raid to steal his neighbour’s leaves! he brings more fresh leaves arranged at each end of this avenue, (sometimes stealing them from the great bowerbird choosing pale neighbours). What the male lacks in objects such as bleached snail shells, bower-building he makes up for in stones, bones and soft drink can ring- mimicry (see Mimics, right) spending pulls as well as green fruits, while the almost every daylight hour at his satin bowerbird prefers blue — bower. feathers, berries, flowers, glass, plastic and so on. Further adornment is added by the males ‘painting’ the inner walls of the avenue with plant matter and Frequency in saliva. The satin bowerbird even uses kilohertz a frayed grass stem as a brush — a rare example of tool use in animals. Time in seconds Time in seconds Interested females enter the avenue, These sonograms show the similarity where mating takes place, after which between calls of three birds (left) and she may be promptly chased away to the male tooth-billed bowerbird's leave the bower free for further mimicry (right). From the top, (left) seductions. white-throated treecreeper, Lewin's honeyeater and pied currawong. Females of the satin and great bowerbirds are also known to mimic The smallest, the golden bowerbird, when disturbed at their nests. They builds the biggest bower. Two towers, usually choose to mimic predatory up to three metres in height, is made birds but can also produce cat and from sticks piled around two saplings human noises. (One great bowerbird, about a metre apart. Often the towers near a quarry, can mimic the noise of are connected by a horizontal perch at rocks being thrown into a trailer and a the sides of which decorations of two-way radio.) Possibly this is done lichens, mosses and pale flowers and to distract a predator by confusing it fruits are added. The beautiful golden with the impression that another male displays on the perch and around individual is present. the area of the bower. The bower may Visiting bowers People are fascinated by bowers — but may unintentionally create a situation last for many decades, often with the Reproduced, with permission, from Emu Vol 96, 1996. same owner, and may be handed down where all the bird’s hard work is in vain. through generations. Bowerbirds put an immense amount of If you want to visit bowers, or take effort into their creations, spending up others to visit them, please put the to 20 years building, renovating and needs of the birds first. decorating. A good bower is the key • Time your arrival carefully so that to a male’s breeding success — as you visit the bower in the middle of long as the females come to visit him. the day. The females visit for mating in Females, however, are shy and if a the morning and evening, so visits bower is frequented by potential between 11am and 2pm will help predators, such as humans, they may minimise this disturbance. stay away. The sad result is that the • Try to stay at least 10-15m away from most spectacular bowers, which attract the bower and make your visit brief. most human visitors, are the most By hanging about, trampling and likely to be a waste of effort. Having dropping rubbish you may not only invested so much time and energy the scare away females but also alert males often cannot afford to start potential predators to the bower’s anew. position.
2 Out and about Tropical Topics reader, Jim Fitzgerald, has collated all the German DNA translations from Tourist Talk into fingerprinting, two alphabetical lists (English-German along with and German-English). He is happy to electromagnetic share these with other readers. To implants, have receive them simply send a stamped been adopted by addressed envelope to the editor, the Queensland address on the back page. A general government in its fight At the second annual Birds Australia index to all Tropical Topics against illicit trade of Atherton Tablelands crane count, newsletters is also available — also on wildlife. The project will initially which took place on 10 October 1998, a receipt of a SAE. Please specify which concentrate on four bird and one total of 1844 cranes were counted at 11 list your require. snake species — the golden- sites. Of these 1255 were definitely shouldered parrot, red-tailed black sarus cranes, 139 were definitely cockatoo, yellow-tailed black brolgas and 450 were not identified. cockatoo, glossy black cockatoo and This means that between one third and In the the green python. A DNA data base one quarter of Australia’s estimated Cape will enable checks to be made on 5000 sarus cranes were present on the Tribulation protected wildlife claimed to have been Tablelands that night. area, workers on bred in captivity or purchased legally. the Marrdja The electromagnetic implant, similar to Definite records of sarus cranes in boardwalk have been those used routinely for identification Australia go back to the 1960s, with treated to the sight of Boyd’s purposes in dogs and cats, can be possible sightings in the 1950s. They rainforest dragons laying eggs. scanned with a special reader. It have been considered recent arrivals They have been digging holes, enables each individual animal to be — natural invaders — but DNA dropping the eggs and then identified with a code which is studies suggest that they may actually covering them up again. eventually matched up on the data have been present for thousands of base with the DNA record. years. This is backed by the fact that their home, the Cape York peninsula All holders who are required to south to the Burdekin and the Gulf of present their animals for fingerprinting Carpentaria, is some distance from the are being contacted by the Department likely point of invasion from Asia. of Environment and Heritage.
Do you have any historical information on the Tableland cranes? If so please call Glenn Holmes on (07) Russell Watson, Resort Ranger on 4091 4364 or Elinor Scambler on (07) Great Keppel Island has reported an 4095 3296. albino welcome swallow flying around the resort. The flying speed of the cranes has been estimated/paced with a car at about 80km/h. With a good tailwind they can fly at over 100km/h. Below is a follow-up from the article on There have been frequent sightings, page 7. recently, in the Cape Tribulation area, of giant land crabs — Cardisoma Dr Garry Cross of the Department of carnifex, featured in Tropical Topics Animal Health at the University of 36. A large claw has been observed Sydney has forwarded his preferred blocking the entrance to a 100mm recipe for wild lorikeet feeding — for diameter burrow but the resident those people who are determined to (about 90mm across the carapace) was feed the birds and who can be certain caught out in the open, one night. of providing a regular supply and to After trying unsuccessfully to hide keep feeding areas scrupulously clean itself against a large tree the crab to prevent spread of disease. scuttled back to its burrow. As it entered it pulled a large leaf across, 2 cups Heinz rice cereal Please note the phone number for effectively hiding the entrance — and 2 cups rice flour the Far North Queensland Wildlife sending a clear message that the show 2 cups canary egg and biscuit food Rescue Association has changed. If was over and the curtain was down! 1 cup glucose powder you find sick, orphaned or injured (Acknowledgments to Hans 1 teaspoon multivitamin mix native wildlife, please call 4053 4467. Nieuwenhuizen) (ABDExtra) The Association has opened a 1 dessertspoon pollen shop front in Cairns at 114 Hoare St. Please bear in mind, however, that it is better not to artificially feed wild birds.
3 Birds as builders Some birds make no nest at all, or at Nesting on water, if you can prevent your eggs from most provide a scrape in the ground becoming waterlogged, gives them some protection from which may or may not be lined with predators. The female comb-crested jacana (right) plops her vegetation and/or stones. Many of scribbled eggs on a raft of vegetation supported by aquatic these are seabirds which rely on the vegetation such as water-lilies — and then leaves dad in isolation of the islands on which they charge. Larger and more aggressive than the males, the nest to protect them from predators — female is the boss in jacana society. She holds a although nightjars, bush stone-curlews large territory which includes the smaller territories and some others nest successfully on of up to five sharing and caring males who devote the ground on the mainland. Ground themselves to incubation and childcare. If one nesters are very vulnerable to predators female successfully challenges another female for and many have been rapidly driven to her territory (and mates) she will promptly destroy all extinction by the introduction of rats, her predecessor’s eggs and chicks, thus ensuring undivided attention from her new cats, stoats and mates. In both sexes, the jacana’s coloured comb, which can change from red to yellow humans to depending on mood, is used to indicate status. previously predator-free Dusky moorhens, a common sight on our fresh waterways, are communal environments breeders. Groups of two to seven birds, with one to three males for each female, such as New work together to aggressively defend their territory. The females mate with all the Zealand. males in the group and nests are created by all members of the commune pulling down vegetation to make a high platform. Eggs are laid together and the parents Roseate tern eggs all take turns to incubate and then to look after the chicks.
Cavities make secure nesting sites. Natural tree holes are the choice of many parrots and kingfishers but some species prefer to
Magpie-lark illustration courtesy Queensland Museum excavate their own cavities in termite mounds. Others, such as bee-eaters, pardalotes and some kingfishers, tunnel into sandy banks.
The eggs of cavity nesters are usually white, or at Buff-breasted paradise-kingfishers nest in ground-level least pale, presumably so parents can see, and termite mounds, creating a tunnel often less than half a metre avoid stepping on them in the dark, and because from the ground. Following this invasion, the termites seal off they do not need to be camouflaged. They the chamber. Given the noise made by the chicks and the smell also tend to be fairly round, which makes from dropped food, it is astonishing that broods are them stronger and more efficient at retaining successful in these vulnerable positions. Many other heat. (Pointed eggs are laid by birds which kingfisher species choose termite mounds higher up, in trees. nest on cliffs, to prevent them from rolling Tunnels are made by the adults flying head on at the mound, off.) occasionally dying from impact.
Almost all parrots form monogamous pairs, Rainbow bee-eaters nest communally, sometimes over 40 birds often for life. Most depend on tree hollows Buff-breasted co-operating to dig nesting burrows, incubate eggs and care so a shortage of these, whether through paradise-kingfisher for the young. Young, unmated males are of particular help in clearing or occupation by introduced birds, limits their lending the adults a hand. ability to breed. Some make very deep nest holes — those of the king parrot may even be at ground level, White-rumped swiftlets build their nests in very large cavities — caves. inside hollow trunks. Excavation of the brood chamber Colonies of tiny cup-shaped bracket nests, made from plant matter and by the female is thought to create the mood for egg feathers cemented together with hardened saliva, are glued closely together laying; darkness stimulates egg-laying in female on the rock walls. Usually one white egg is laid in each. The swiftlets budgies. negotiate the dark caves using echo-location. Orange-footed scrubfowl In the Wet Tropics, we are lucky to have two of the world’s 19 species of megapodes (bigfeet) — the mound builders. Although hardly the most beautiful of nests, the incubating mounds of the Australian brush-turkey and the orange-footed scrubfowl are the largest of any birds. Measuring, on average, three to four metres in diameter and one metre high, the brush-turkey’s mound normally contains two to four tonnes of material. Those of the scrubfowl, which are added to each year by different birds, are even bigger and can weigh over 50 tonnes. The mounds need to be big, and contain enough fresh material, to generate sufficient heat. This is created by the respiration of micro-organisms, particularly certain types of fungi. (Overseas, related birds use the heat from volcanoes.) Only the male brush-turkey (below) builds the mound, 5deg of an average 33deg. The male tests it and adds or removes spending 5-7 hours, raking about 56kg of material, each day for material, sometimes making ventilation holes, as necessary. Exactly over a month. The female devotes her energies to the how the male takes the temperature of the mound is in some doubt. production of what are particularly big eggs with very large It has been suggested that he uses the bare skin on his head, his yolks, needed during the long incubation. (The shells are also feet, bill or neck sac but no studies have confirmed these particularly thin, allowing the embryo to more easily obtain possibilities. It is likely to be the palate or tongue since both males oxygen underground and also allowing it to make a quick and females regularly take a bill-full of mound material, apparently escape, and quicker access to external to sample it. oxygen, at hatching time.) The male then tends the mound. Any It seems that females choose their mates according to how well overheating, or cooling, they build and look after their mounds, inspecting all males in the endangers the eggs as does area and observing their behaviour before making their choice. too much or too little They also probe the mound to test its temperature and other moisture or lack of air. The properties. The owner of a good mound may find females queuing temperature of the brush- up to lay their eggs in his care. A female will usually remain with turkey’s mound remains her chosen partner for 3-6 weeks, laying eggs in his mound before remarkably constant, within moving on to another male, with a fresher mound, to start again.
4 Cup nests come in many forms. Some, like those of many honeyeater Ospreys add to their bulky species are slung from a fork in a branch, suspended by cobwebbing. stick nests year after year. Often clearly visible, they are frequently built close to the end of Built on rock faces and branches which are too delicate to bear the weight of many (dead) trees, and often predators. reaching gigantic proportions they may The spectacled monarch’s nest (right) is often built only a metre serve to advertise a pair’s or two above the ground. Like many cup-shaped nests it is territorial claims. (They decorated with pieces of lichen and spiders’ egg-cases. These are also pose a problem to thought to help conceal the nest from predators not by adopted Telstra towers camouflaging it but by breaking up the dark shape. The pale and similar human lichen decorations reflect light, giving the illusion that the nest is see- pieces structures.) through and therefore not actually there. There is no need for them In Australia, the nests of apostlebirds, to be white-winged choughs and magpie-larks (left) are made from camouflaged mud. Beakfuls of mud are first fashioned into a platform on the or hidden chosen branch and then the walls of the nest added. Bits of because it would be an unusually brave vegetation are included to strengthen the structure and the predator to take on a bird of prey. mud tapped to release trapped air. Nevertheless owls and snakes may pose a problem. It has been observed that willie wagtails often build their nests near to those of magpie larks. Perhaps these two aggressive species benefit from nesting in close proximity, combining forces to chase away predators. The nests of many pigeons and doves seem to consist of not much more than a beak-full of twigs and a Covered nests are useful for hiding the contents prayer. It is surprising that they from predators and protecting them from the hold eggs, let alone wriggling elements and are nestlings, but the commonness particularly of many species, for example the prevalent in the peaceful dove which is a Wompoo fruit-dove tropics. The minimal nester, means they must serve their purpose. It has spindle-shaped been suggested that these nests may dry out quickly after nests of some species, rain. Flimsiness, however, may be an illusion; the sticks in notably the yellow-bellied nests of superb fruit-doves were found to consist of forked sunbird (left), dangle in the twigs which were locked into place and difficult to pull apart. open but are remarkably easy to miss. The large-billed gerygone’s, hanging Young pigeons and doves, uniquely among birds, are fed on above water, looks very like just another milk. Resembling cottage cheese this is produced in the adults’ piece of flood-abandoned vegetation. The crops and is the only food given to the chicks for the first three huge colonies of metallic starlings (right), days. It is high in protein and produces the highest growth rates however, are nothing if not conspicuous with of any nestlings. This must be of particular importance for fruit- hundreds and sometimes thousands of the birds doves whose adult diet is low in protein. hanging their nests from the same tall rainforest tree. There may be safety in numbers but when grey goshawks raid the nests the starlings do Cuckoos are well-known for their habit of laying eggs in not combine forces to mob the predators. others’ nests. However, about two-thirds of the world's species (91 of 136) do their own work and raise their own young. Australia has one nest-building cuckoo — the pheasant coucal The golden-headed cisticola, like the better (left). It first tramples down a platform of vegetation quite close to known tailor-bird of nature documentaries, sews the ground and then pulls down other plants to make a domed living leaves on to its nest. Built in grass roof with two entrances — a necessary escape route for an tussocks or similar vegetation in swampy areas, incubating bird. the nest is dome-shaped with a side entrance. It seems that the male and Most female parasitic cuckoos deposit their eggs during the laying period of female work together, the female inside the the host bird, at a time when the host is away feeding, often removing one so nest and the male outside, passing strands that her addition will not be noticed. Sometimes, if she has missed the laying of cobweb through holes in the leaves to period, the cuckoo will remove nestlings from the nest of a potential host, forcing stitch them into place. them to start again and thus giving her the opportunity to join in.
It is possible a young female cuckoo learns to Pittas build bulky dome-shaped identify (imprint) on its foster parents and Less well-known are the birds which, nests on or near the ground, later lays in nests of only that species. (In the in addition to making their own nest, often between buttress roots. most advanced cuckoos, different ‘tribes’ of dump a few eggs into the nests of Some also place a collection one species stick strictly to one host species, other birds of the same species. This of animal dung in front each inheriting an ability to mimic that happens among some swallows, of the nest. This may particular host species’ egg colouring. More finches and waterfowl. Most foster serve to disguise recently evolving parasitic cuckoos, such as parents are unable to detect the the smell of the the pallid cuckoo, lay their eggs in the nests intruder’s eggs and raise them as their nest from of over one hundred species and have even own. The patterns on coots’ eggs, predators such as however, vary from one individual to Noisy pitta been seen feeding cuckoo nestlings. They brown tree snakes. are still getting the hang of the business of another so if a female detects a being neglectful parents.) ‘foreign’ egg in her nest she will often toss it out.
5 Questions & Answers Facts and stats The Wet Tropics and Great Barrier Q Why are sea snakes abundant in specialises in eating fish-eggs and Reef have a larger number of bird species some reef areas and which species has almost lost its fangs, teeth and than any other region of the same size in are common? venom glands. Australia. More than 430 species have A Sea snakes are common in some Usually only one species of sea been recorded — over half the total areas but rarely seen in others. snake is readily identifiable, with number of bird species found in Unfortunately, reasons for this little chance of mistake. This is the Australia. Thirteen species are endemic. patchy distribution are unclear. They yellow-bellied sea snake (Pelamis do occur in large numbers in the platurus). This is a pelagic species Clutch sizes depend on species. Some Swain Reefs where dozens may be that is occasionally seen around lay a fixed number of eggs but others can seen during a dive in areas known, reefs. It has a black dorsal surface replace any which are lost. Domestic appropriately, as the ‘snake reefs’. and a bright yellow belly. chickens can, of course, keep producing They are also very common on but some wild birds are similarly Ashmore Reef, northern WA. Another group of sea snakes, the productive. One (a type of woodpecker) sea kraits (Laticaudids), feed in the was persuaded to lay 71 eggs in 73 days Of 31 species of ‘true’ sea snakes sea, but return to the land to lay as they were successively removed from (Hydrophiids) approximately 14 are eggs, and often to sleep (by day). the nest. The sizes of some clutches are potentially found around the Swain Laticaudids are quite competent on related to food quantities available at the Reef area. These are the most land and can even climb into low time and vary from year to year. Australian specialised, or most adapted to life in hollow logs and so on. Records of birds have small clutches compared with the sea — they live a totally aquatic these snakes in Australian waters similar species elsewhere. Interestingly, existence, giving birth to live young. are very scant. Both species are the average clutch sizes of introduced Most have considerable difficulty characterised by bold black and birds seem to be declining. moving on land. white or bluish-white and black bands. Around seven of these sea snakes (Acknowledgments to Eric Of the 24 smallest birds in the world are regular reef inhabitants. Probably Vanderduys, Queensland Museum) over half build domed nests. the most commonly seen is the olive sea snake (Aipsyurus laevis), a Co-operative breeding has been recorded relatively large (up to 1.2m) species in 12 percent of Australian bird species which is highly variable in colour. — but in only 2.5 percent of bird species Like most sea snakes it is highly worldwide. Many Australian co- venomous and has an unnerving operative breeders originated from the habit of approaching and twining same ancient Gondwanan bird group. around divers. Happily, it rarely bites, unless attacked, and since its fangs, Birds which breed co-operatively tend to like those of most sea snakes, are lay smaller numbers of eggs in one quite short, only large specimens can clutch than similar birds which breed in bite through wet suits. pairs — but are much more likely to produce more than one brood. Another, the turtle-headed sea snake, (Emydocephalus annulatus) is, White-winged choughs are an extreme unusually, non-venomous. It example of co-operative breeders. The young are dependent on their parents for years as they slowly learn to become efficient foragers — and do not become sexually mature until they are about four. If a pair tries to breed without help their chicks invariably die of starvation. So Olive sea snake necessary are helpers, they even kidnap young birds from neighbouring territories and recruit them into their group. Young chough helpers can be deceitful, however. They have been Tourist talk observed approaching the nest with food, ENGLISH GERMAN JAPANESE dangling it above the youngsters’ open co-operative zusammen kyoryoku mouths and then, if no other chough is arbeiten watching, scoffing it themselves! nest Nest su The males of three percent of bird bower Laube azumaya species (246 worldwide) have penises. cuckoo Kuckuck kakkou These include emus, cassowaries, kiwis mound Bruthuegel tsuka and all waterfowl. cavity Astloch kudou lichen Flechte chi i A starling’s nest with three chicks was found on the back of a live sheep which to mimic nachahmen monomane suru was about to be sheared. disease Krankheit byoki feathers Federn hane
6 Promiscuous fairy-wrens Just as the structure of the human family has become more varied, studies have shown that some bird families are also far from conventional.
Fairy-wrens are co-operative breeders. To the outside world fairy-wren tribe appears to be, their tendency the group appears to be a close-knit one, the breeding male to stray is bound to be beneficial, introducing with his bright colours presiding over a breeding female and genetic diversity into what could otherwise be a number of males which, outside the breeding season, a dangerously inbred group. often adopt feminine plumage. (Adolescent females, not tolerated by mum, are driven away.) One big happy, closely This social structure is not the norm for all co-operative related family? Definitely not! breeding birds. Similar studies of noisy and bell miners, which also form large groups, suggest that the breeding Genetic studies of superb and splendid fairy-wrens have pairs are faithful to one another. However, ‘extra-marital’ revealed the shocking fact that a high proportion of the affairs are fairly common among white-winged choughs, a young are not dad’s. It appears that, from time to time, mum species which is unable to raise young without help. Stable entertains the neighbouring males, mating with up to six groups of these birds tend to be quite inbred, the dominant different ones in addition to her regular partner. Similarly the pair often breeding incestuously, but from time to time male fairy-wren, decked in his brightest costume, a flower deaths due to conditions such as drought force the birds to clenched in his beak, also goes philandering — siring chicks regroup and cross-breed again. with up to 10 other females. Shockingly promiscuous as the
Food for the birds You wouldn’t raise your children on a diet of lollies so it is not fair to feed a similarly poor diet to wild birds. ‘runners’, and the disease as ‘runner syndrome’. The virus is spread, very easily, through the birds’ droppings, even from affected birds which have made a recovery. This means that feeding stations, which artificially attract large numbers of birds together provide perfect conditions for the disease to spread.
Meat is often fed to carnivorous birds such as kookaburras, magpies, butcherbirds and currawongs but is deficient in calcium and can lead to a softening of their bones and beaks. Bread causes all sorts of digestive problems. Another problem with artificial feeding is that birds become dependent on it and suffer if it is suddenly stopped. They may also breed more frequently than normal creating an imbalance in the bird populations. For example, small birds will suffer from large numbers of hunters such as butcherbirds, kookaburras and drongos. Also, since nest sites do not get a rest during which viruses would die off, they instead persist to move from bird to bird. Artificially fed birds also lose their natural fear of humans and can Feeding birds is a popular way of attracting them closer, in become aggressive when demanding food and easy prey for tourist resorts, backyards and picnic spots, but it is a very domestic pets. selfish thing to do. It can cause many problems. The best way to attract birds to your garden or resort is to For a start, the digestive systems of non-human animals are provide them with a natural diet by planting suitable native not geared to cope with processed foods and the bread, plants. Grevilleas and bottlebrush trees attract rainbow sugar, honey and meat fed to the birds lack essential lorikeets as do many rainforest trees and shrubs. The little nutrients. Rainbow lorikeets are among the most frequent euodia (Evodiella meulleri) is a perfect small tree for this. victims. In the wild they eat large amounts of pollen which is Rainbow lorikeets, as well as honeyeaters, spend hours high in protein — essential for growing new feathers after clambering among the pink blossoms which cover its moulting. However, the diet of sugar and honey which is branches for weeks in spring. The scarlet flowers of the often offered to them contains very little protein. As a flame tree (Brachychiton acerifolius) are also attractive result, rainbow lorikeets are frequently found with feathers favourites as are the branching flower heads of the umbrella which are too short for successful flight. A sugary diet is tree (Schefflera actinophylla). A clean shallow bird bath, if also deficient in vitamins and minerals, which makes birds it can be placed safely and regularly maintained, is also susceptible to diseases, while the fermenting sugar creates useful for attracting birds. ideal conditions for the growth and spread of harmful micro- organisms. For those who are determined to feed rainbow lorikeets and to take on the responsibility of doing so regularly and Of particular concern is Psittacine Beak and Feather keeping feeding areas scrupulously clean, Taronga Zoo Disease. This is an extremely infectious virus which affects recommends fresh fruit and budgie seed. A nectar mix can parrots and may be spread also to cockatoos and possibly be made from three parts Heinz high protein baby cereal, to doves and pigeons, often with fatal results. The disease one part honey plus one teaspoon Petvite vitamin impairs growth of the long feathers essential for flight and is supplement per cup of nectar mix. Add enough water to easily passed from parents to their young. In this case the make a porridge and use only at the rate of one teaspoon chicks, when launched from the nest, cannot fly and fall to per bird. It should be placed in the shade and old food the ground instead. These unfortunate birds are known as always cleaned up.
7 Bookshelf General: Co-operative breeding: Nature Australia Vol 25 No 7 Court site constancy, The Life of Birds Nature Australia Vol 25 No 8 Summer 1996-7 dispersion, male survival David Attenborough Autumn 1997 (Fairy-)Wrens through the and court ownership in the BBC (1998) When good help is hard to eye of a sceptic male Tooth-billed find Steve van Dyck Bowerbird The book of the TV series. Rob Heinsohn Clifford and Dawn Frith Bowerbirds: Bird behaviour Co-operative breeding, incest Wingspan Vol 8 No 2 June Bird feeding: Robert Burton and kidnapping in white- 1998 Simply Living Aug 1996 Granada (1985) winged choughs. Bower Power Polly wants a cracker Clifford and Dawn Frith Janie Burton Taylor Reader’s Digest Complete Nature Australia Vol 25 No 9 Book of Australian Birds Winter 1997 Emu Vol 96 Part 1 March Simply Living Dec. 1994 Reader’s Digest (1993) The politics of parenting: an 1996 Don’t feed the birds avian perspective Visual evidence of vocal avian Lyn Matts Interpretive Birding Michael J.L. Magrath mimicry by male Tooth-billed Bulletin Bowerbirds Jacanas: Published six times a year, Corella Vol 19 No 3 Sept. Clifford Frith and Michael Nature Australia Vol 25 No for $30, this is available from 1995 McGuire 2 Winter 1997 The Editor, 136 Payne St, Co-operative breeding in Signals of the flesh Indooroopilly, QLD 4068. Australasian birds Emu Vol 95 Part 2 June 1995 Natalie J. Demong and M.F. Clarke Stephen T. Emlen
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