Spring is coming to North America and scientists are quietly excited. Little pygmy lemurs wake up after months of hibernation – the first time these furry fat-tails have gone into a long hibernation in captivity.
New research, which has simulated seasonal conditions to hibernate captive lemurs, much like their wild relatives do in western Madagascar, suggests these animals may return to wild hibernation after decades of captive breeding.
“We were able to recreate their wild conditions well enough to make them mimic their natural conditions [hibernation] patterns, ”said Erin Ehmke, a primate biologist at the Duke Lemur Center where the study was conducted.
The study’s findings should not only help improve care for dwarf lemurs in captivity, but also provide scientists with new ways to study the biological trickery hibernating animals use to endure extreme environmental conditions.
(Lydia Greene)
Fat-tailed dwarf lemurs are masterful hibernators, hibernating for up to seven months a year, depending on conditions. It is an extreme survival tactic used by many mammals for 250 million years.
Dwarf lemurs, which use fat stores in their tails to get through the winter in Madagascar, are actually our closest hibernating primate relative. To conserve energy in hibernation, their heart rate levels almost flat, their body temperature plummets, and their breathing slows to the point where scientists have observed a hibernating lemur go 21 minutes between breaths.
Studying hibernating animals is more than a jealous curiosity for scientists as it could one day improve human health. While it remains in the realm of science fiction for now, researchers are looking to the science of hibernation to find ways to help people survive long-haul flights, make operations safer, and possibly even prevent disease.
In this study, the research team followed eight dwarf lemurs, the descendants of a few wild animals brought to the Duke Lemur Center decades ago, over a months-long artificial winter to see if these animals could hibernate, similar to their wild counterparts.
“Hibernation is literally in their DNA,” says Duke University primate biologist Marina Blanco.
Yet despite the best efforts to care for captive animals, they tend to behave differently from their wild friends, especially when it comes to hibernation – something scientists have known for quite some time, and is most likely due to the unnatural conditions in climate-controlled zoo habitats with food in abundance.
Studies have shown that captive dwarf lemurs, for example, fall into much shorter periods of shallow hibernation, called torpor, than wild lemurs, with these energy-saving dormant species rarely lasting longer than 24 hours in captivity.
Whether this is just a temporary disruption in hibernation patterns or whether captive lemurs have lost the physiological ability to hibernate remains a bit of a mystery.
The researchers showed that pygmy lemurs are indeed capable of sustaining months of hibernation in captivity, supporting the idea that hibernation in these animals is biologically wired and can be reactivated under the right conditions.
Before going downstairs, the animals were equipped with radio transmitters to measure their heart rate and skin temperature, and housed in cozy, temperature-controlled enclosures with wooden boxes designed to mimic tree hollows.
The researchers gradually adjusted the lights for Madagascar’s short wintery hours, turned the thermostat dial to 10 degrees Celsius (50 degrees Fahrenheit) and restricted the animals’ food – then watched and waited.
From October to February, the lemurs spent nearly three-quarters of their time in metabolic slow-motion: curled up, cool to the touch, barely moving or breathing for up to 11 consecutive days, showing little interest in food.
It is noteworthy that few studies have experimented with limiting food to captive animals – even though hibernation is an extreme energy-saving strategy that animals use to survive when food becomes scarce.
“That males were fed more frequently, had more brief periods of sedation, and generally stayed asleep for fewer hours than females (although our sample size is too small to be definitive) suggests.[s] that diet may have influenced the dynamics of the anesthetic to some extent, ”the researchers wrote in their method paper.
The lemurs, now waking up from their months of sleep, look healthy, the researchers report, with the animals’ heart rates returning from 8 beats per minute (bpm) to about 200 bpm – and with it their appetite.
Now that the animals are recovering well, researchers want to schedule more studies leading up to next year’s winter, as long-lived lemurs may also hold secrets to proper aging.
“Until now, if you wanted to study hibernation in these primates, you had to go to Madagascar to find them red-handed,” Blanco said. ‘Now we can study hibernation here [in captivity] and watch more closely. “
The research is published in Scientific reports.