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.
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