A numb baby observed during the study. Credit: Curtin University
Australia is known for its wonderful and unique wildlife. But, just like the rest of the world, Australia is expected to get even hotter due to climate change. This could be a disaster for many marsupials that live in the drier parts of the country, as it could be too hot for them to handle.
To make matters even more difficult, many of these marsupials are endangered due to habitat loss and the introduction of species such as domestic cats and red foxes. It is therefore essential to find a way to study these animals without disturbing them to ensure their survival.
This awareness led Christine Cooper (Curtin University, Australia) and Philip Withers (University of Western Australia) to use infrared cameras and computer models to determine how hot it can get before the torpor (Myrmecobius fasciatus ) cannot withstand the heat. They published their findings in the Journal of Experimental Biology.
Researchers found that high air and soil temperatures limit the length of time numbs can feed in the sun to about 10 minutes, after which the animals must retreat to the shade. In even more extreme conditions, the high temperatures of their environment as well as radiant heat from objects in the environment and humidity can threaten the numbskulls’ survival, even in the shade.
Cooper and Withers hiked the forest trails of two Western Australian Wheatbelt reserves – Dryandra Woodland and Boyagin Nature Reserve – in 2020 and 2021 to film around 50 numbats using their infrared camera. The researchers also used a portable weather station to measure air temperature, relative humidity, solar radiation and wind speed, which they combined to obtain a measure of true environmental temperature.
Numbats are the only marsupials active only during the day. In fact, the team found that marsupials are in the sun 62 percent of the time. So, how does being in the sun affect numbness’s temperature?
Cooper and Withers measured the surface temperatures of different areas of the numbskull’s body when they were in sun and shade. Not surprisingly, researchers found that direct sunlight allowed numb people to quickly gain heat. But being exposed to direct sunlight accounted for only 18% of the heat the numbs gained, so the numbs must have gained heat elsewhere. In fact, numbskulls who tried to cool themselves by retreating to the shade during high temperatures continued to gain heat, even though they were not exposed to direct sunlight.
This led researchers to conclude that heat from the air and ground, as well as radiant heat from objects in their surroundings, are the main heat sources contributing to a numb person’s risk of overheating. For this reason, the team concluded that soon, even the shade will be too hot to help the numbskulls stay cool.
Cooper and Withers then calculated how long the numbskulls could forage for food before their body temperature reached 40°C (the warmest body temperature recorded for an active numbsku). The team found that if the air and ground temperature (not direct sunlight) increased to 23°C, the numbskulls could only stay in the sun for 10 minutes before their body temperature does not reach 40°C.
This poses a huge problem for numbnuts because their only food source is termites. Termites are not very nutritious, so the numbskulls must eat large numbers of them to survive. Termites live deep underground and only come to the surface when the ground warms during the day. This means that numbnuts can only feed during the day, when the sun has warmed the soil enough for the insects to be close to the surface, within reach.
Because of climate change, the future of the numbskulls looks bleak. They cannot feed at night when the temperature drops because their food will be too deep for them to reach and they will be vulnerable to predators. They also won’t be able to survive in the shade if the climate continues to warm as predicted, due to rising temperatures. heat stored in air and rocks. Something must be done to stop global temperatures rising, otherwise one of Australia’s iconic marsupials could become another tragic example of a creature we could have saved.
More information:
CE Cooper et al, Implications of heat exchange for an endangered free-living marsupial determined by non-invasive thermal imaging, Journal of Experimental Biology (2024). DOI: 10.1242/jeb.246301
Provided by The Company of Biologists
Quote: Climate change is a disaster for numb termite lovers (January 11, 2024) retrieved January 11, 2024 from
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