A new study reveals that sloths, the iconic slow-moving creatures of Central and South America, may be facing an existential crisis due to climate change. The research, conducted by scientists, suggests that the energy limitations of these animals could make survival untenable by the end of the century, especially for high-altitude populations.
Metabolic Challenges for Sloths
The article, “Sloth Metabolism May Make Survival Untenable Under Climate Change Scenarios When Latitudinal Variability is Considered,” seeks to understand how different ambient temperatures affect the physiology of two-fingered sloths (Choloepus hoffmanni) living both in lowland and highland areas.
The researchers measured oxygen consumption as well as core body temperature of sloths in an experiment simulating projected climate changes using indirect calorimetry. However, the researchers concluded that their findings bode ill for the future of sloths, with a bleak outlook for those living at high altitudes. Commenting on the findings, lead author Dr Rebecca Cliffe said: “Sloths are evolutionarily unique as mammals in that they have an extremely slow metabolic rate and have a very poor ability to thermoregulate when compared to other groups of mammals. Sloths, especially those in high-altitude areas, could be physically unable to persist through the extreme heat predicted for 2100, our research has found.
Survival Strategies for Lowland and Highland Sloths
The research found that when higher temperatures do arrive, sloths from highland regions skyrocket up their resting metabolic rate (RMR). Lowland Sloths in contrast to their highland relatives are better adapted to higher temperatures, but when they become too high that would bring them out of an area which is considered as thermally active zone (TAZ), a survival response takes place where metabolic depression was activated.
In fact, such projected temperature increases (2–6 °C) will translate into a significant increase in metabolic scope-limiting regions for high-altitude sloths by the year 2100. But their low energy-processing capacity — along with their lack of mobility and variation in geography to move across as temperatures rise — might hold them back from adapting to climate change. Because the slow rate of digestion of sloths (0.12 g/min) is up to 24 times slower than that of other giant herbivores, this may have also presented an additional challenge. Given that sloths do not consume food with a high-quality carbon source, an increase in metabolic demand as a result of climate change would likely require larger food intake — a precarious feat for this low-level herbivore to constancy maintain energy balance.
Conclusion
Results from this study underscore the necessity for conservation action to protect sloths against climate change, especially at high elevations. With the iconic animals facing an uncertain future, scientists are urging more in-depth studies on what horses and hairy rhinos can do to survive a rapidly warming world.
