JUNE 27,
2019
Research
published in Biology Letters by scientists at Western Sydney
University provides the first clear evidence that a species of perching bird
(the passerines) can employ torpor—an energy-saving mechanism whereby the body
temperature of an animal is temporarily reduced in a controlled way during
resting.
In this
new research, the authors used miniature radio-transmitters to record the
skin temperature of
these tiny eight-gram birds over
several weeks during winter in woodland near Sydney. Skin temperature provided
a close approximation of body temperature in such small animals. Remarkably,
they showed these fairy-wrens allow their body temperature to decrease
substantially during their nightly roosting phase. These periods of nocturnal
torpor closely resemble the torpor that is well-known in some small mammals and
in a few non-passerine bird groups like hummingbirds. This new evidence of
regular use of torpor by a passerine bird is important for understanding the
physiology and ecology of birds.
Birds are
typically small and light, which helps them to fly and escape from predators
but means they cannot carry a lot of fat and this presents a challenge during
winter when food is hard to find. The use of torpor provides a very effective
mechanism to reduce the amount of energy required for thermoregulation when
resting during the night. Torpor could be an important strategy allowing small birds to
cope with limited and fluctuating food supplies.
"Even
in a relatively mild climate, superb fairy wrens benefit from the
energy-savings that nocturnal torpor provides," said Dr. Christopher
Turbill from the Hawkesbury Institute for the Environment at Western Sydney
University.
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