Mallee Hen Nest: Sandalwood, South Australia
I have never seen a Mallee Hen in their natural habitat.
Despite frequently visiting their nests (Which is more a dug out hole that looks like a mound) and living in the Mallee throughout my childhood, they successfully eluded me and my curious family and friends. The chattering and the vibrations from our excited approach toward their mound probably warned them: however they have pretty much developed quite a few survival techniques and characteristics- one of them being their plumage camouflaging into their environment. The other main tactic is to run really fast and hide in trees.
I was very excited to see two mallee hens in the Adelaide Zoo last week, and it got me to thinking about why we have always been so interested in this elusive little bird. They are classified as vulnerable in the Riverland Mallee area of South Australia. Before the arrival of Europeans, the Mallee Hen ( also known as the following; Malleefowl, Gnow, Lowan and the Mallee Hen, and, in the central desert of Australia, by the aboriginal name Nganamara.) was found over huge swathes of Australia. They settle in semi-arid mallee scrub on the fringes of the relatively fertile areas of southern Australia, where it is now reduced to three separate populations: the Murray-Murrumbidgee basin, west of Spencer Gulf along the fringes of the Simpson Desert, and the semi-arid fringe of Western Australia’s fertile south-west corner. In these areas they range from being threatened to endangered, and in some areas, such as the Northern Territory, they have not been seen at all for many years.
They have tactics to run away from their many predators- feral cats, foxes and above all, the human and their land clearing ways. They can jump onto a branch to avoid a hungry fox, but in the long term, the Mallee Hen is vulnerable due to ongoing destruction and fragmentation of their habitat and the effects of bushfire and drought.
Even my Dad has a reverence for these little birds- perhaps because they are a stark reminder of the impact of land clearing for agriculture and the destruction of natural habitats.
What do they look like?
The Mallee Hen (Leipoa ocellata) is a ground-dwelling, chicken-sized bird with strong feet and a short, chicken-like beak. As you have probably guessed, it is a distant relation to the chicken.
Mallee Hens belong to a family of 22 bird species known as megapodes. Also known as incubator birds or mound-builders, megapodes are stocky, medium-large, chicken-like birds with small heads and large feet in the family Megapodiidae. Their name literally means “large foot” and is a reference to the heavy legs and feet typical of these terrestrial birds.
When I finally saw a real one at the zoo, I thought it looked about the size of a small turkey. Perhaps the birds in captivity are bigger due to a constant source of food and are complacent due to a lack of predators.
The head and neck are mostly grey, with a dark stripe extending from the throat to the upper breast, and the underparts are mostly very light brown. The upper wings are patterned with a palette of greys, cream and black.
The bill is black and the legs and feet are pale grey. Male and females look similar; not like other birds where the male has all the showmanship! There is a lonely peacock roaming around the machinery sheds- he makes enough noise and shows off for us all.
In their natural environment, Mallee hens pick at food items on the ground or on low shrubs or scrape the leaf litter to expose food. They mostly eat seeds, flowers and buds, and occasionally also invertebrates. Hopefully, they enjoy eating the bull ants which live in nests surrounding this particular mound. I had to quickly take photos as I was a moving target around the mound according to the local bull ant population. I have only ever been bitten once by one of these ferocious little beasts, and it HURTS, I tell you.
Nest building- the Mallee Hen Mound
Mallee Hens are one of three mound-building birds in Australia, and the only species that live in arid areas. (The others are the Brush Turkey and the Orange-footed Scrub-fowl.)
As their name suggests, Mallee Hens prefer areas dominated by ‘mallee’ – multi-stemmed, low-growing, eucalyptus vegetation. They need a sandy soil and lots of leaf litter to build their nesting mounds.
In order to reproduce, these industrious little megapodes dedicate 9-11 months per year building and maintaining a large incubation mound of soil, leaves and twigs. The eggs are laid in the mound, buried and left to incubate by heat generated from the composting litter.
Sometimes the hens recycle and reuse old mounds- but is they are starting from scratch (pun intended) this is the process; the Mallee Hen uses its strong feet to scrape large amounts of leaf litter and sand from the ground and into a large pile. In winter, the male selects an area of ground, usually a small, open space between the stunted trees of the mallee, and scrapes a depression about 3 m across and just under 1 m deep in the sandy soil by raking backwards with his feet.
In late winter and early spring, he (yes- the male is the mound-building one!) begins to collect organic material to fill it with, scraping sticks, leaves, and bark around the hole, and building it into a nest mound, which usually rises up to around a metre above ground level. The amount of litter in the mound varies; it may be almost entirely organic material, mostly sand, or any ratio in between.
After rain, he turns and mixes the material to encourage decay, and if conditions allow, digs an egg chamber in August (the last month of the southern winter). The female sometimes assists with the excavation of the egg chamber, and the timing varies with temperature and rainfall.
- This cross-section of a mound shows a layer of sand (up to 1 m thick) used for insulation, an egg chamber, and layer of rotting compost. The egg chamber is kept at a constant 33°C by opening and closing air vents in the insulation layer, while heat comes from the compost below.
- The female usually lays between September and February, provided enough rain has fallen to start organic decay of the litter. The female helps with the digging and lays the eggs. One egg is laid every four to eight days, with up to 24 eggs in one breeding season.
The female lays in instalments (clutches) of two or three to over 30 large, thin-shelled eggs,(mostly about 15); usually about a week apart. Each egg weighs about 10% of the female’s body weight, and over a season, she commonly lays 250% of her own weight. The amount of eggs laid at any given ‘clutch’ varies greatly between birds and with rainfall. Incubation time depends on temperature and can be between about 50 and almost 100 days.
- The male continues to maintain the nest mound, gradually adding more soil to the mix as the summer approaches (presumably to regulate the temperature).The male checks the temperature of his breeding mound regularly, and scrapes material onto or off the mound to keep the temperature just right. The Mallee fowl has developed a highly sophisticated method of temperature control for egg incubation. The birds maintain the mound temperature of 32-34 degrees by using their beak as a “thermometer” and adjusting soil cover to either retain or expel heat from the egg chamber.
- Chicks hatch unaided at around 60 days. Hatchlings use their strong feet to break out of the egg, then lie on their backs and scratch their way to the surface, struggling hard for 5–10 minutes to gain 3 to 15 cm at a time, and then resting for an hour or so before starting again. Reaching the surface takes between 2 and 15 hours. Chicks pop out of the nesting material with little or no warning, with eyes and beaks tightly closed, then immediately take a deep breath and open their eyes, before freezing motionless for as long as 20 minutes.
- They can walk as soon as they emerge and can fly within 24 hours! Just as well really- the parents don’t care for the hatched young, who rely only on camouflage for their survival. The chick then quickly emerges from the hole and rolls or staggers to the base of the mound, disappearing into the scrub within moments. Within an hour, it will be able to run reasonably well; it can flutter for a short distance and run very fast within two hours, and despite not having yet grown tail feathers, it can fly strongly within a day. Chicks have no contact with adults or other chicks; they tend to hatch one at a time, and birds of any age ignore one another except for mating or territorial disputes.
Put simply: the eggs are then laid into a cavity at the top of the mound and covered over. As the leaf litter begins to compost it generates heat and this is used to incubate the eggs, rather than dad or mum sitting on them. When the little ones hatch, they are all on their own in the world. You would think that after all the effort to make the nest, the parents would have an investment in the survival of their young. Few chicks survive: most are eaten by foxes, cats and other predators.
For this reason, naturalist John Gould chose the Latin name Leipoa ocellata meaning the ‘spotted egg-leaver’.
Threats to the Mallee Hen
The Mallee Hen is vulnerable as a species. Besides the relatively low rate of survival of these little chicks in the wild, habitat loss was, and continues to be, the biggest threat, with much of their natural habitat cleared for agriculture or substantially modified by sheep, cattle, goats and rabbits. It is pretty safe on Mum and Dad’s farm- they have a whole paddock fenced off and the nest is monitored by a little camera. Predators, of course, can get through the fences but at least it is safe from accidental human interruption, eg. People on quad bikes hooning around! Their remaining distribution is severely fragmented, and isolated populations increase the species’ risk of extinction.
It is not just human activity which determines the suitability of their environment. Mounds need vegetation which can be temperature controlled- an area which habitat was has not been burnt for 40–60 years is preferred; frequently burnt areas are unsuitable and do not support Mallee Hen populations. Therefore any controlled or uncontrolled fires are a threat to current and future populations. Drought also impacts upon food sources and the suitability of mound vegetation. This part of Australia is not known for its abundant water supply or rainfall, as you can see from these photos. Thank goodness for the water of the Murray River not far away for the Riverland fruit and vegetable crops. This section of the Mallee is dependent upon bore water, as well as the occasional rain. The early settlers’ only source of fresh vegetables was from drop off deliveries from the now-abandoned train service- there is not even enough reliable rainfall for a family vegie patch here.
Most of the detailed information I found out about the Mallee Hen is from the website Beauty of Birds. However, I have heard all about the dear little thing for most of my life. Many a pleasant picnic afternoon in the 1970s was spent stalking the nests. If I could find any photos of these times I would certainly have included them, if only to laugh at the colours of our rain jackets and our home haircuts. I’m kind of glad they have evaded us, because they need some peace and quiet in order to reproduce and lead a happy life in their Mallee home.