This article is from
Creation 13(4):10–12, September 1991

Browse our latest digital issue Subscribe

Peeping in on the thermometer bird

An Australian bird knows when the temperature is just right

by Robert Doolan

New-born chicks of the Australian mallee fowl can hatch only because their parents can take temperature. If the mallee fowl parents didn’t know when the temperature of their egg chamber was 33 °C (between 91 and 92 °F), their eggs wouldn’t hatch and there would be no more mallee fowl. In fact, if the parents are wrong by more than just one degree either way, it’s bye-bye birdie!

Mallee fowl don’t sit on their eggs, like most birds do to let their body heat incubate the eggs. They build a large mound and monitor its temperature with their bill and tongue. When the first white settlers in Australia came across these huge mounds in the late 1700s, they thought they were Aboriginal burial mounds. Only later did they discover the grayish-brown, spotted birds that built them.

The mallee fowl starts building its mound when the breeding season approaches in spring. The parents first dig a pit almost a metre (three feet) deep. They gather leaves, twigs, bark and other plant material, and scrape them in to fill the pit. When some rain soaks into the debris, the birds build it up into a heap by covering the litter with a thick layer of sand or soil.

As the vegetation begins to rot, the heat increases in the mound — like compost heap that gardeners use. The male probes the mound with his bill to check the temperature inside. When both parents are satisfied that the temperature in the mound is 33 °C, the hen lays her first egg. She then lays a single egg each week or two for the next five or six months. Usually she will lay 15–20 eggs over this time. As each egg is laid, the male opens the mound and carefully moves the egg into the right position. He then works on the mound to prepare it for the next egg.

Amazing display

The hen usually begins laying in late September — the southern hemisphere spring. From that time until about April, the male uses his beak and tongue to ensure that the temperature of the mound stays constant. In an amazing display of temperature sensing, the bird will alter the structure of the mound to maintain the temperature at 33 °C. When the heat increases inside the mound because of the rapidly decaying plant material, he uncovers the eggs to let air circulate around them. He protects the eggs from the hot summer sun by adding sand or soil to the mound as a shield.

When autumn arrives, and the cooler weather causes temperatures to drop, the male uncovers the mound early in the day so the heat can reach the eggs. He covers it again in the evening to retain the heat.

Each egg needs seven weeks’ incubation. This means that some eggs will be hatching while the hen is laying others. The newly hatched chick has up to 15 hours of hard work ahead of it. It has to tunnel its way through nearly a metre of soil and other material to reach the open air. The chicks are able to look after themselves from the moment they hatch and can fly within 24 hours.

Designed and planned

The mallee fowl is sometimes called the ‘thermometer bird’ because its assessment of the mound’s temperature is so accurate.

To the creationist, the mallee fowl’s ability shows remarkable design and planning by the Creator. Both male and female birds work together to prepare their egg-chamber, yet they also specialize in different tasks. The male is able to constantly monitor, and alter if necessary, the precise temperature needed to hatch the eggs laid by the female. The new-born chicks have to find their way through a metre of soil unaided, and can fend for themselves from the moment they hatch. Everything must work perfectly through a long cycle.

But try to think how the mallee fowl’s breeding cycle could evolve. How would the male and female determine their duties? How could the chicks know they must keep tunnelling for up to 15 hours? What if the newly hatched chicks gave up after an eight-hour day? And how would the male know, from even his first try at parenting, that he must maintain the temperature through various seasons and weather conditions at exactly 33 °C or he won’t produce any chicks?

If the first mallee fowl parents didn’t get everything exactly right, there would be no more mallee fowl. Instinct and perfect design implanted by the Creator of all life is by far the most reasonable explanation for the existence and perpetuation of the mallee fowl.

Another ‘bigfoot’?

The mallee fowl belongs to a group of birds known as megapodes — meaning ‘big feet’. Megapodes are large-footed birds which live in Australia and other islands of the Pacific.

They all construct mounds of earth or vegetation either for display — as does the super lyrebird — or as an incubator for eggs, as do the mallee fowl and the brush turkey. The largest of these megapode mounds may be two metres (6.5 feet) high and 13 metres (more than 40 feet) across. They may contain 12 tonnes or more of earth.

The mallee fowl’s mound is not the largest, but the bird’s big feet allow him to dig a sizable pit for the female to lay eggs, and to scrape dead leaves and plants from the surrounding areas to fill the pit.