At first whiff, you might think all skunks are the same. Not so.
Meet spotted skunks, "the acrobats of the skunk world." Scientists have discovered that there are more of these species than they thought, according to new research.
More recently, the agreed-upon number was four. But a new study published Wednesday in Molecular Phylogenetics and Evolution said there are seven spotted skunk species.
"North America is one of the most-studied continents in terms of mammals, and carnivores are one of the most-studied groups," said study author Adam Ferguson, Negaunee collections manager of mammals at the Field Museum in Chicago. "Everyone thinks we know everything about mammalian carnivore systematics, so being able to redraw the skunk family tree is very exciting."
Spotted skunks are the smaller relatives of the common striped skunk. About the size of a squirrel, these elusive carnivores live across North America. And when the time comes to scare off a predator, these little guys perform a handstand and kick out their back legs.
"When they're stressed, they bounce up onto their forelimbs and then kick out their hind limbs, puff their tail up, and they actually can walk towards the predator, like basically making them look bigger and scarier," Ferguson said.
The skunks typically drop back down to all fours in order to take deadly aim and control their vile-smelling spray. Their small stature doesn't cause these creatures to back down from a fight, either.
A study released in 2013 included a video of a Western spotted skunk handstanding and facing off with a mountain lion over a deer carcass. For reference, spotted skunks typically weigh less than 2 pounds (0.9 kilogram).
It's just another example of their boldness, something he admires about skunks in general, Ferguson said.
While the common striped skunk has made its presence known in urban areas, as well as its natural habitats, striped skunks haven't made the same inroads and so largely remain out of sight. These "ecologically cryptic" creatures live in dense environments and remote areas and seem less adaptable to urbanization than their larger, striped counterparts, Ferguson said.
Given their agility, spotted skunks are great climbers, and they are a lot more carnivorous than other skunks, feasting on bird eggs, lizards, snakes and rodents. Great horned owls are their main predator.
The fact that spotted skunks are so good at keeping a low profile makes them harder to study. Since the discovery of the first spotted skunk in 1758, scientists have questioned just how many species exist. Over the years, the differences observed between some spotted skunks led researchers to believe there were as few as two species and as many as 14.
Making the determination that there are seven species came down to analyzing genetic data from spotted skunks. But first, Ferguson needed specimens to study. Trapping skunks isn't the easiest job -- Ferguson and his colleagues made six trips to Mexico while researching spotted skunks and never caught one. And if you do trap one, you're bound to be sprayed.
"We call it the smell of success because it means we've actually encountered one, which is the goal ultimate goal," Ferguson said.
Ferguson was inspired to make "wanted" posters and distribute them across central Texas in feed stores and areas where ranchers and trappers operate. The posters described the need for any spotted skunks that may have been trapped or found as roadkill and showed photos of the creatures. The researchers offered to come pick up the skunk specimens and store them in a designated "skunk freezer."
The researchers also relied on specimens in museum collections, which included spotted skunks found in Central America and the Yucatan. In the end, they had 203 spotted skunk specimens to use for the study and extract DNA. The genetic data revealed that some of the skunks, once considered to be the same species, were in fact very different.
"I was able to extract DNA from century-old museum samples, and it was really exciting to see who those individuals were related to. It turns out that one of those was a currently unrecognized, endemic species in the Yucatan,'' said study author Molly McDonough, a biology professor at Chicago State University and research associate at the Field Museum, in a statement.
One of the new species from the study is the Yucatan spotted skunk, which is about the size of a squirrel and only found in the Yucatan Peninsula. The scientists also describe the Plains spotted skunk, whose population has been declining over the last century and has been suggested as an endangered species.
"The study wouldn't have been possible without the museum specimens we had," Ferguson said. "The only reason we were able to get sequences from the Yucatan were museum specimens that were collected 60 or 70 years ago."
Understanding individual species of skunks can help scientists learn more about something unique to these creatures: their reproductive biology. Spotted skunks may breed in the fall, but they don't give birth until the spring. In other words, their reproductive system purposefully delays implanting the egg inside the uterus.
"It just sits in suspension for a while," Ferguson said. "We want to know why some species have delayed implantation and others don't, and figuring out how these different species of skunks evolved can help us do that."
Skunks have come a long way since they first appeared in the fossil record 25 million years ago, evolving and splitting into different species by responding to the climate change caused by the ice age.
Knowing more about spotted skunks can also help conservation efforts to protect these animals. Skunks have their own role to play within the ecosystem, consuming fruit and defecating seeds that help with the dispersal of plants, as well as preying on crop pests and rodents, Ferguson said.