Squirrels are among the craftiest of critter life on Earth, notorious for their skills of scrambling and dodging dogs, cars and more. But USA Today reports on evidence that squirrels take even greater safety measures than we have imagined. It seems that squirrels scent themselves in rattlesnake essences as a safety measure to avoid predators. Further, they have done so for at least 18 million years.
Barbara Clucas of the University of Washington in Seattle led a team of biologists who studied the squirrels. As the team wrote in their study currently featured in the Journal of Evolutionary Biology, "Recently, two squirrel species were discovered to anoint their bodies with rattlesnake scent as a means of concealing their odor from these chemosensory predators.” And how exactly do said squirrels anoint themselves in “eau de snake”? Biologists report that the animals chew up shed rattlesnake skins and then lick their fur. Further, the team found that "Squirrel species with historical and current co-occurrence with rattlesnakes all expressed snake scent application.”
Clucas and her team looked at how 11 species of squirrel disguise themselves, focusing on how the animals manipulate rattlesnake, weasel, and deer scents to their benefit. They also looked at how some North Pacific rattlesnakes reacted to mice burrows that did or did not smell of snake. (Not surprisingly, the rattlesnakes liked mice burrows that did not have their scent.) The team also considered fossil records to see how far back the practice went. They found that scent application probably happened from a common ancestor around 18 million to 28 million years ago.
Squirrels have evolved over the past 36 million years from just one spot in North America to a place in most of the world. They have been so prolific that experts have begun to look at their evolution as a signifier for geological and climate change.
John M. Mercer and V. Louise Roth are Duke biology professors who have studied the animals. As they shared in a study, “By modifying habitats and creating bridges and barriers between land masses, climate change and tectonic events [land mass movements] are believed to have important consequences for diversification of terrestrial organisms."
Ultimately, it seems that as the Earth changes, squirrels follow. With such survival disguises in hand, it is no wonder the squirrel has made such a prolific mark on the ever-changing landscape of our planet.
For further reading:
- Rattlesnake perfume a longtime squirrel safety measure
- Squirrels evolutionary family tree reveals influence of climate, geology