Breeding Behaviour of the Wild Budgerigar
Continued from Wild Budgerigars: Part One
From an evolutionary viewpoint, the budgerigar (Melopsittacus undulatus) moved into an environment that satisfied its dietary, water, breeding, and hence survival needs. Few environments can satisfy all the needs of fauna. However, in the harsh desert and semi-desert environment of Australia budgerigars have managed to adapt and flourish across a broad range of soil types, temperatures, rainfall and latitudes.
There is a strong correlation between flora and soil types, however, rainfall, temperature, wind velocity and the movement of sediment determine which flora will predominate. An enormous variety of annual and perennial grasses, forbs (flowering plants), shrubs and trees exist across the many different environments inhabited by budgerigars. Budgerigars occur across a number of varying topographical habitats. Some may be used for breeding and others for survival. We have used the following land types (Perry 1962) as an ecological guide to the soil types and flora available to the budgerigar for survival and breeding.
Porous, infertile sandy deserts and gibber deserts cover at half of the vast range of the Budgerigar. These deserts are unlike the mobile sand dunes of the Sahara desert as they are capable of supporting specialised vegetation such as Spinifex and small forbs. Budgerigars are unable to breed in deserts because temperatures are too high in summer and too cold in winter to support an adequate food supply. Additionally suitable nesting trees and water sources are lacking. Budgerigars were seen to move into the Simpson Desert in search of food. Spinifex may be the only food available to budgerigars in a drought year. Drought years are experienced approximately every five to seven years in the desert area (Isaacs 1987) and may last for up to ten years. Spinifex grasses and other tussock grasses become green and lush after fire or rain and provide a survival food for budgerigars.
Like the Australian aborigines, budgerigars move large distances in their seasonal movements. Falling rain can be seen in the desert for up to 80 kilometres at ground level. The Budgerigar Dreaming paintings (aboriginal ontological stories) by Pintupi artist, Malcolm Jagamarra, depict budgerigars spiralling skyward then leaving en masses in a north west direction on their migratory journey in search of food and water. In flight budgerigars are able to see vast distances and are capable of flying 500 kilometres in a single day. Seasonal migratory pathways of budgerigars may be predicted to avoid deserts and also follow seasonal wind patterns.
The breeding grounds of budgerigars may be predicted from the soil types and associated flora. Riverine woodlands provide the best breeding habitat for budgerigars. These breeding grounds occupy narrow strips fringing rivers or depressions and support trees of the Eucalypt family. The trees provide perfect nesting hollows and protection from heat and predators. The completion of the breeding cycle of budgerigars is dependent upon a special set of climatic and seasonal circumstances. Rain and temperature combined with suitable nesting trees, topography, soil types and associated flora dictates the success or failure of breeding outcomes. Often many different soil types and their associated flora are found within distances that are of no burden to the athletic budgerigar who is capable of flying considerable distances in a short time.
Flood plains associated with the Finke River and Sandover River study sites are mainly red, sandy earth soils. Such soil types provide budgerigars with potentially good feeding grounds during a breeding season. These areas support short lived and spectacular forbs of many types especially after flooding rains.
Brown, grey or red poorly drained cracking clay soils on gently sloping plains outside Newman are mostly treeless and support medium height perennial tussock (Spinifex) grasslands of variable density. At Delmore Downs the most dominant of these grasses was Barley Mitchell Grass (Astrelba pectinata). Spinifex and Mitchell Grass are both drought tolerant grasses that respond after rain. Fire stimulates regeneration of both these grasses. They are considered to be survival rather than breeding grasses for budgerigars because of they have a moderately high food value and only when green.
Sand dunes composed of coarse infertile soils extending north east of the Delmore study site supported Mulga (Acacia aneura) under which grow short lived grasses and forbs. These plains were not far from the breeding grounds and would have been used during breeding.
Fairly shallow limestone country found especially north east of Alice Springs and at the Delmore Downs study site supports Witchetty Bush (Acacia kempeana) with an understory of short grasses and forbs. Witchetty Bush also grows in fairly shallow acid stoney skeletal soils and red earths associated with Spinifex. Budgerigars require an immediate source of calcium when laying eggs and calcium rich soils or lenses of calcium must lie close to nesting trees in a breeding environment.
The dry riverbeds of the Finke River breeding grounds study site are rich in calcium (limestone and other mineral salts washed down over time). Here there is no shortage of calcium for budgerigar hens to lay eggs. At the Delmore Downs breeding grounds study site calcareous red earths overlying limestone provide the necessary calcium rich soils required by breeding budgerigars. This soil type supports low open woodland or a low forest of Gidgee (Acacia georginae) above low short-lived grasses and forbs. The Gidgee is taller and denser than the Witchetty Bush (Acacia kempeana). In more open land red earth supports short lived grasses that may be used by budgerigars as feeding grounds during breeding.
Shallow and gritty soils overlying a granite base support low open woodlands of Iron Wood (Acacia estrophiolata), mulga (Acacia aneura), White Wood (Atalaya hemiglauca) and Cork Wood (Hakea suberea). Grasses and forbs are present in this region after rain. This habitat also provides protection for budgerigars during the heat of the day.
The number of possible breeding grounds available to budgerigars is restricted by the availability of nesting trees. Eucalypts provide budgerigars with suitable nesting hollows. Eucalypts and therefore potential breeding rounds are rare across the range of the budgerigar.
The flora across the range of the budgerigar occurs in various forms, as trees, shrubs, grasses, herbs, forbs and flowering plants, each with its own soil and water needs. The distributions of Mulga woodlands and budgerigars across Australia are closely aligned. Mulga woodlands grow mainly on red earths. By extracting nutrients deep in the soil and recycling them in leaf fall individual plants act as nutrient pumps.
A characteristic feature of mulga and budgerigar lands is the unreliability in amount and season of rainfall.
Mulga is extremely resistant to moisture stress. They use their shape to channel water down to their trunks and into the ground creating a mini-refuge for grasses such as Mulga Grass (Aritida contorta) and Window Mulga Grass (Thyridolepis mitchellana) that have a very high food value and are favoured by budgerigars.
Grasses occur as annuals or perennials and both produce an abundance of small seeds. Annuals otherwise known as ephemerals have adapted to resist heat and drying out and may survive for long periods of drought. After rain germination is rapid and a lifecycle that may be as short as a month. Perennials range from grasses to shrubs to tall trees whose deep roots are paramount to their surviving in the arid environment and during flash flooding. Budgerigars take full advantage of the rapid germination, short life cycle of highly nutritious annuals such as Native Wooly Oat following rain. Perennials are more numerous and provide the breeding budgerigar with a sustained supply of food.
The nutrient content of grasses is higher in the early vegetative state of growth (Fisher 1973) but many grasses dry out before the budgerigars are attracted to them. There are many grasses available to the budgerigar after rain. Of the 132 arid and semi arid area grasses classified by Lazarides, 114 were found north east of Alice Springs and extending past Quilpie in Queensland. The variety decreased southward with 98 varieties in the Northern Territory-Finke River-South Australia region but decreasing towards each of the deserts and especially in Western Australia as well as the Darling River system in New South Wales. The diversity of summer annual and perennial grasses present at Delmore Downs has already been noted in the 1930's by a South Australian scientific expedition.
Native grass seeds are much higher in protein and fat levels than commonly cultivated cereal plants such as wheat (Isaacs 1987). Nutritionally they provide enormous amounts of energy and a high quality protein for breeding budgerigars. Although most seeds are small each grass bush bears heavily. Herbs and succulents also provide breeding budgerigars with many nutritious seeds. Grasses of Panicum, Brachiaria and Eragrostis genera seem to predominate and are common throughout central Australia, particularly near and along watercourses, in floodplains and mulga areas favoured breeding sites. Particularly nutritious grasses include Woolybutt Grass (Eragrostis sp.), Summer Grass and Native Millets (Panicum decompsitum). Barley Mitchell Grass (Astrelba pectinata) and succulent Portulaca species also found at the Delmore Down study site are particularly nutritious and staple for the Pintupi aborigine people.
Grasses of the deserts are mainly tussock spinifex of a number of varieties. Aborigines do not use spinifex as a staple. Budgerigars use it as a survival food in times of drought. Budgerigars may also use bandicoot Grass (Monachather paradoxa) together with Cane Grass and Long Tails (grasses specific to the Simpson Desert) during drought.
Buffel Grass (Chenchrus ciliares) is an exotic drought resistant grass introduced from the Northern Hemisphere. It is now widespread, has a relatively high food value and is favoured by budgerigars. Although it is overtaking the native forbs and grasses in some regions it appears to have little detrimental effect on the breeding outcome of wild budgerigars. Buffel Grass was widespread at the Delmore Downs site.
Summer grasses are utilised by breeding budgerigars. A large variety of summer grasses were available to breeding budgerigars at Delmore Downs. Donald Holt classifies summer grasses as those that grow from between September and May. They included the highly nutritious Golden Beard Grass (Chrysopogon fallax), Native Millet (Panicum decompositum), Summer Grass (Brachiaria miliiformis), Button Grass (Dactyloctenium radulans), Native Oat Grass (Enneapogon avenaceus), Wooly Oat Grass (Enneapogon polyphyllus) and Threeawn Grass (Eriachne aristidea) to provide quality food in summer.
Donald Holt classifies winter grasses as those that complete their life cycles in the months of June to September. Winter grasses including Pussy Cat Tail, Golden Beard Grass and Poached Egg. They may provide budgerigars with quality winter nourishment as a survival rather than breeding food, as there is a strong bias for budgerigars to leave Delmore Downs in winter and migrate northward where it is warmer. Winter grasses are of little significance to budgerigars across central Australia because they appear when it is too cold to breed.
Budgerigars were observed eating forbs and flowering plants at the Delmore Downs and Finke River study sites. These short lived heavy seeding smaller plant contribute a dietary supplement and variation to the budgerigar diet especially during breeding and particularly in a good season when the desert "blooms" in a carpet of colour. Bright purple Parakeelya (Calandrinia parakeela) is widespread after heavy rains and grows on sandy loam, sand plains and dunes. They flower in summer followed by capsules containing large numbers of minute kidney shaped black seeds, which when piled in a heap, look like black sand. Each plant bears a large quantity of seeds that are highly nutritious and an ideal food for breeding budgerigars. These succulents are water, vitamin and mineral rich being most valued during hot weather and drought.
The wild budgerigar uses nesting hollows found in Eucalypts. Eucalypts are considered rare compared to Mulga across the enormous range of the budgerigar. The opportunity for breeding habitats is limited by the availability of these nesting hollows. Suitable breeding grounds for budgerigars may be predicted by the presence of Eucalypts or soils that support Eucalypts. Eucalypts belong to the Myrtaceae family. They prefer deep river bed soil where their roots extend down to the underground water reserves and are found along more defined river courses. Ghost gums (Eucalyptus papuana) and (Eucalyptus microtheca) provide nesting holes for breeding budgerigars in Queensland's Channel Country. Budgerigars were seen nesting in Red River Gums (Eucalyptus camaldulensis), Coolibahs (Eucalyptus coolibah) and Ghost gums (Eucalyptus papuana) at the Finke River and Delmore Downs study sites. Budgerigars may nest almost anywhere within an established breeding ground when breeding conditions are ideal and nesting hollows become unavailable. Budgerigars were seen nesting in Whitewood (Atalaya hemiglauca) at Delmore Downs and under rocks at Finke River.
Breeding grounds must provide Eucalypts for nesting protection, calcareous red earth soils or limestone country to provide an immediate source of calcium for laying eggs, a water supply and a nearby environment that supports seeding grasses, herbs, forbs and other potentially nutritious plants after rain.
Temperature and rainfall then determine when breeding should occur within these breeding habitats.
Successful breeding outcomes remain a seasonal activity for budgerigars in the wild although rain dictates their breeding behaviour. Breeding opportunities are erratic and rely upon the availability of food. Food supply must be sustained in order for budgerigars to complete their breeding cycle. The plants that budgerigars use in order to reproduce have adapted to the same inhospitable environment and unpredictable rainfall. Grasses make up the bulk of the wild budgerigars' diet, especially after rain, followed by forbs.
Except during drought it is not excessively dry across the northern range of the budgerigar (at the Finke River and Delmore Downs study sites) where breeding grounds are found. However, a summer rainfall pattern works against plant growth and budgerigar breeding across this region. Summer rains are often in the form of heavy thunderstorms but their effect is short lived because extreme temperatures and high evaporation rates prevent sustained plant growth. The likelihood of a breeding outcome increases as temperatures moderate towards the end of summer when there remains a possibility that downpours may create conditions that favour sustained plant growth.
Delmore Downs represents an ideal breeding environment for the wild budgerigar but it remains an uncommon event for very large numbers to breed. Donald Holt runs the Delmore Downs cattle station. As a third generation occupier of Delmore Downs he has an intimate knowledge of the conditions required for sustained plant growth. From talking with Mr Holt and his mother, Jesse Holt, it was concluded that budgerigar breeding is determined by a rapid flush of seeding grasses and other desert plants after a sequential rain pattern with the best breeding seen when this sequence occurs in March.
The rain sequence starts with a substantial fall of around 25mm (personal communication with Donald Holt). The initial downpour germinating the seeds. A follow-up rain of at least 5mm two weeks after the first guarantees the plants and grasses complete their cycle and continue to do so irrespective of follow up rains. After such a sequence of rain there is a bountiful supple of feed as long as the temperatures are not too high. Breeding success is assured when the above sequence occurs when moderate temperatures arrive at the beginning of autumn (March). Even though the average rainfall during December, January and February may be higher than for March native plants and grasses on Delmore Downs rarely complete their life cycle because very high temperatures burn off the shooting grasses. Similarly breeding was abandoned at Lake Tandou when high temperatures "burnt" off food supply.
Budgerigars are stimulated into breeding condition by the first rains but require the second rain two weeks later to complete their breeding cycle. The entire life cycle of the grasses is utilised by breeding budgerigars. Germination of desert grasses and plants is usually rapid producing tasty sweet high-energy shoots within a few days after rain. Names such as Eight-Day Grass (Fimbristylis dictoma) and Five-Minute Grass (Tripogon lolliforms) reflect their very short life cycle. Eight-Day Grass germinates in two days after rain or storms and completes its life cycle within a very short time. This valuable grass is widespread across Delmore Downs and is favoured by budgerigars when green. Umbrella Grass (Digitaria brownii) and Barley Mitchell Grass (Astrelba pectinata) are also most nutritious when "green". Wooly Oat Grass (Enneapogon polyphyllus), Native Millets (Panicum decompsitum) and Parakeela (Calandrinia remota) provide their highest food value when dry. The oil and protein rich Parakeela seeds are a favorite of budgerigars. The energy rich shoots stimulate the birds into breeding condition.
Breeding continues whilst the grasses continue to germinate and provide a rich source of energy. After an initial heavy downpour and follow-up rain there is a plentiful supply of food for budgerigars to continue breeding until summer grasses start to die off under the effect of shortening day length and decreasing nighttime temperatures.
By June, after completing their autumn breeding cycle, budgerigars leave Delmore Downs because there is not enough high-energy foods to support breeding. They fly off in a north-easterly direction to avoid the Simpson desert and head towards the warmer temperatures of Queensland.
The modern day exhibition budgerigar has lost none of the instincts that have made its wild budgerigar cousin such a successful breeder. The nomadic budgerigar has adapted to the harsh conditions of Central Australia superbly by surviving during the dry times on very limited nutritional resources and then very quickly breeding after seasonal rainstorms turn the desert into an oasis of seedling grasses and nutritious plants of enormous diversity. In the desert, the life of plants is very short lived and the budgerigar breeding cycle has evolved around the nutrients provided by these seeding native grasses and desert plants. After rain there is a great variety of seeding grasses and plants available for the breeding budgerigars to feed their young, but without further follow up rain or permanent water holes this food supply dries up very quickly.
The wild budgerigar will only start breeding when the natural conditions indicate that there is a very good chance of breeding success. The aviary budgerigar must follow nature's same rules. Rainstorms play a most important part in the life of desert plants and consequently for the breeding success of the wild budgerigar. It is a unique stimulus for desert breeding but the wild budgerigar is also influenced by the ancient seasonal breeding instincts common to all birds with temperature and day length playing important roles in breeding success. Instincts still present in the aviary budgerigar can be used to improve their breeding success.
The wild budgerigar starts to breed when it is in breeding condition. Aviary budgerigars must also be in breeding condition to successfully complete their breeding cycle. Desert life completely determines the breeding cycle of the wild budgerigar. In summer wild budgerigars do not breed in Central Australia because even after rain the plants do not survive for long in the intense heat. Summer therefore is an ideal time for the nomadic budgerigar to replace its feathers in what is referred to as its "annual moult". Normally, the wild budgerigar replaces its body feathers, wing and tail feathers during December, January and early February. During cold winter desert nights, when the temperature drops to below freezing, the budgerigar is insulated and waterproofed by a thick cover of down feathers. These are produced continuously throughout the year. For wild and aviary budgerigars summer is a time for the natural annual moult. Breeding of exhibition budgerigars should also not occur during the heat of summer.
In budgerigars, there is an intimate link between the moult and breeding. The end of the moult is heralded by the appearance of pin-feathers on the head and at this time the budgerigar shows a heightened level of activity and vitality. This heralds the onset of "breeding condition" in budgerigars and the best time to start breeding aviary budgerigars.
The moult primes the budgerigar into breeding condition. The monsoon rains and seasonal rainstorms of late summer in northern Australia coincide with the completion of the "annual moult", a perfect time for the budgerigar to start breeding as it is in perfect physical condition and primed physiologically to come into breeding condition.
A sudden change in weather can stimulate a short body moult in aviary budgerigars. A sudden hot or wet spell often stimulates a moult in the aviary and this appears to be a remnant of the link between the moult and breeding condition in the wild budgerigar. In summer, a hot spell triggers the aviary into the "annual moult" with tail and wing feathers being dropped and replaced sequentially. At other times and especially in late winter and spring wet spells accompanied by warmer temperatures induce a partial body moult that often sends healthy budgerigars into breeding condition.
After rain, a short body moult primes the wild budgerigar into breeding condition. The wild budgerigar has adapted to the severe conditions of the desert outback because it conserves water and energy so well. It is extremely energy-efficient flying vast distances in search of food and water even after food supplies have dried up. Under these conditions it is in "survival mode" and in no physical condition to breed. Breeding starts only after the grasses and plants come to life turning the red desert into a green carpet of seedlings. The energy efficient budgerigar quickly converts the energy and nutrient rich sprouts into a short body moult.
Autumn is the best time for the wild budgerigar to breed. For over a million years the weather patterns and climatic conditions have brought rain to Central Australia during autumn. Summer grasses and plants have relied upon moderate temperatures and rains for their continuing existence and the budgerigar has adapted perfectly around Autumn breeding. Similarly, across Australia except for the cold southern and inland regions such as Canberra, Melbourne and Tasmania, autumn is the best time for aviary budgerigars to start breeding. Spring is the best time for southern states to start their breeding season.
In winter, the conditions in the desert are not favourable for breeding. The wild budgerigar, as do all birds, retains the breeding patterns of its ancient forebears. In winter, the desert nights are often below freezing. Winter rains do produce native grasses and many are frost resistant but as winter moves towards shorter days the grasses die off and breeding activity declines because of food shortage and the ancient effect that a shortening day length depresses breeding activity.
Winter breeding for aviary budgerigars is hazardous in cold climates. Aviary budgerigars already on eggs or with youngsters may breed successfully in winter in some warmer areas but breeding failure is inevitable when breeding is commenced within a month of the shortest day of the year. June 23rd in the Southern Hemisphere and December 12th in the Northern Hemisphere are critical times for the budgerigar breeder because budgerigars do not naturally come into breeding condition when it is too cold or the day length is too short. Artificial lighting and heating may be used to increase the day length and improve breeding results.
Spring is naturally a very good time for wild budgerigars to breed. The wild budgerigar responds favourably to the increasing temperatures and day length of spring when seasonal native grasses and desert plants provide the wild budgerigar with the energy stimulus to breed. In many areas of Central Australia a spring flush occurs after an especially wet autumn has filled the water table. After such seasons wild budgerigars will breed prolifically around permanent water holes in the absence of rain. Aviary budgerigars breed well towards the end of winter and early spring when the days are lengthening and becoming warmer. Good breeding results for aviary budgerigars are enjoyed when breeding starts a week or more after the shortest day of the year as long as it is not too cold.
Summer is the most dangerous time to breed aviary budgerigars. Summer is the natural time for the moult and in aviary birds establishes the breeding and health pattern for the entire year. When breeding starts or continues into summer, budgerigars are placed under considerable stress because they postpone their annual moult until the end of breeding when they often fall ill because they have not replenished their depleted nutrition and energy levels. The heat of summer places breeding budgerigars and their young under further stress often precipitating Polyomavirus (French Moult) outbreaks in otherwise healthy flocks. Breeding should be stopped in the first month of summer and resumed only after the new tail feathers are fully-grown and pin-feathers appear on the head.
The incorrect breeding season starting time is the most common cause of diseases of captive-bred budgerigars. Excessively high infertility, dead in shell, sick and dying hens and poor development of the nestling are common when the birds paired are not in breeding condition. In Australia this occurs most often when breeding starts during the natural moulting season of December, January, February, when it is too cold or the birds are paired too close to the shortest day of the year.
The budgerigar fancier can use the natural cycles of the wild budgerigar still present in the aviary budgerigar to improve the breeding results. The exhibition budgerigar is more susceptible to breeding failure and illness than the wild budgerigar, but still retains many of the strong survival characteristics of its ancestors. The most important part of breeding success is to start breeding at the best possible time and not to breed during the budgerigar's natural moulting season, when it is too cold, too hot and just prior to the shortest day of the year.
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We would like to thank Ray Ackroyd for his "outback" naturalist knowledge, expertise in locating budgerigar nests and capturing birds for inspection. Thanks also to John Scoble, Mrs Jesse Holt (now deceased), Donald and Janet Holt. Professor Barbara Rice of Macquarie University assisted in the classification of grasses, flowers and forbs that were collected. Casey Rowe helped edit and proof read this paper.
Andrew McFarlane's soft food recipe is eagerly consumed by breeding birds.
Information on the significance of Polyomavirus on the overall health and breeding success of exhibition budgerigars.
"The Budgerigar" is an internationally acclaimed definitive text on exhibition budgerigars.