Finding the elusive eastern spotted skunk

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Documentation of the mid-century eastern spotted skunk population decline by Gompper and Hackett (2005).

The eastern spotted skunk is an elusive, potentially rare and endangered species of skunk native to much of the eastern US between the Rockies and the Appalachian Mountains. The species was common throughout its range at the beginning of the twentieth century and people often saw eastern spotted skunks on family farms. During the 1940s and 1950s however, eastern spotted skunk populations crashed. The population decline is well documented, but reasons for the crash remain unclear. Hypotheses for the decline range from the expansion and modernization of agriculture to overharvest to disease. Likely, a combination of several concurrent factors lead to the decline. Eastern spotted skunk populations never recovered, remaining at low levels across much of their historic range.

Today, researchers are working with state wildlife agencies to identify where eastern spotted skunks are and determine which resources they need to maintain healthy populations. In some states, large-scale surveys for eastern spotted skunks resulted in no sightings, suggesting the species is locally extinct in parts of its historic range. Other states have identified populations and are working to understand whether the populations are at a healthy level.

In Arkansas, eastern spotted skunks were historically present across the entire state and recent surveys have revealed the species still has strongholds in the Ouachitas, or the western region of the state. It was with this knowledge the Arkansas Game and Fish Commission funded my research to determine whether eastern spotted skunks are present in the Ozarks, and if so, which resources they’re using. I conducted a large-scale camera trap survey in north-central Arkansas to answer these important questions. Although I recorded eastern spotted skunks at some camera trap sites, preliminary results suggest the species occurs at extremely low population levels in this part of the state.

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An eastern spotted skunk visits a camera trap site in north-central Arkansas.

Using the information gathered from my camera survey, I decided to produce a species distribution model. This type of model uses presence-only data to evaluate where a species is most likely to be present based on characteristics of locations where we know eastern spotted skunks spend time. Using presence-only data means that I will only use camera trap locations where eastern spotted skunks were recorded. For example, from approximately 75 camera trap locations, eastern spotted skunks were photographed at only 4 sites. Failure to record an eastern spotted skunk at a camera trap site doesn’t necessarily mean the species is absent at that site; it simply means we don’t know for sure that eastern spotted skunks use that area. Thus, the locations where I recorded eastern spotted skunks on camera traps are “known locations.” I will use the 4 known locations where eastern spotted skunks were confirmed and exclude the remaining 71 camera trap locations for my species distribution model.

In addition to the 4 known locations from my camera trap survey, the eastern spotted skunk species distribution model will use an additional 72 known locations from eastern spotted skunk surveys by other researchers in Arkansas and southern Missouri. I will determine what the environment was like at the known locations, including how close they are to roads and other infrastructure, how close they are to water sources, and how dense the forest is at each location. Using this information, the species distribution model will predict where eastern spotted skunks are most likely to be across all of Arkansas and southern Missouri. For example, if most of the known locations are in areas where the forest is thick and dense, the model will predict that eastern spotted skunks are most likely to be in other thickly forested parts of the state and less likely to be in open fields.

Although the large-scale camera trapping survey I conducted resulted in limited eastern spotted skunk photographs, the species distribution model approach allows me to use these data. The final product will be a heat map of Arkansas and southern Missouri, with warm tones suggestive of eastern spotted skunk populations and cool tones meaning eastern spotted skunks are not likely to occur in those areas. The map will be useful for state wildlife agencies as they continue to determine where the species is and create management plans to prevent further population decline of this unique mammal.

 

Will you be at The Wildlife Society Annual Meeting in October 2018? Come to my talk on Tuesday, October 9 to see the results of the species distribution model.

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A Turtle on a Tall Mountain

A couple of summers ago, I was trapping flying squirrels in the North Carolina mountains.  It was a normal day at work and I was mostly concerned with the squirrel trapping grid we had laid out atop Roan Mountain.  That was until we found a turtle.

The unassuming box turtle found atop Roan Mountain.

Box turtles are docile, adorable, and make for great photo ops, but rather than gather it up for some Instagram-worthy pics, we only looked at it, confused.  This turtle was hanging out in the middle of a spruce-fir forest 1,875 meters above sea level.

Let me put this in perspective.  Roan Mountain is one of the tallest mountains in North Carolina.  It reaches so high that many wildlife species common across North Carolina don’t dare venture to the peaks of the Roan Highlands.  Ticks are unheard of there, a unique scenario for anyone working summer months outside in the southeastern U.S.  When North Carolina experienced a massive heat wave that summer, the squirrel team switched from long-sleeved t-shirts to short-sleeved for a couple of weeks.  The temperatures are cooler and the forests different on a peak as tall as Roan’s.

When we found this turtle on Roan Mountain, we were simply stupefied.  We didn’t think box turtles as a species existed at such heights, but there it was—a turtle, on a tall mountain.  It offered no apology or explanation, so like any good scientist, we did some digging later that day and discovered what we already suspected—box turtles had never been recorded at such a high elevation in the southern Appalachians.  This turtle was a maximum elevation record.  This turtle was noteworthy.

This morning I am preparing to step into a highly-publicized movement and declare my love for science to the world.  I am participating in the March for Science in Columbia, Missouri.  This public space is not commonly occupied by scientists.  It is true that science has had its moments, but we largely stay out of sight, fueled by our own curiosity.  We sit in our labs and offices running experiments, recording data, and writing papers.  But, this movement has been brewing for months and unlike a quiet turtle on a tall mountain, we are stampeding into this unexpected space, unified and loud.

I anticipate today will be easy.  I am marching with friends and fellow scientists and we will be surrounded by smiling faces who support the work we do.  After the march, we will discuss our research with the science-loving public at a local festival.  But then what?  Are the ears on Capitol Hill listening?  Are climate change deniers opening their minds to real scientific evidence?  Are we really making strides in how the public perceives science?

Today is not a challenge.  Today we collectively throw ourselves into the public eye, a space where we aren’t expected.  Where we go from there is the challenge.  Perhaps we scientists belong in everyday life the way a box turtle belongs in a spruce-fir forest on top of a mountain.  It’s unexpected, not wrong.  So here’s my suggestion: don’t leave this public space we’ve come crashing into.  Stay visible.  Keep talking about your work, keep putting it out there in a way that anybody can digest.  And don’t apologize about being in that space.  Don’t offer an explanation.  Be present in that space until it’s expected.  Be noteworthy.  Be a turtle on a tall mountain.

You.

Read the turtle note here.

How to Catch a Deer

Several years ago, I was having a relaxing morning at my parents’ house when my little brother walked inside, apparently exhausted. He went straight for the cabinet, plucked a cup off the shelf, filled it with water, and chugged the full cup…twice. Breath caught, he looked at me. “I tried to catch a deer.”

White-tailed deer are a fairly common site near our suburban North Carolina home. They make regular early morning appearances—regular enough, in fact, that our garden is now fully fenced in an effort to keep them out. They are fun to watch from the window, coffee in hand, but they tend to make haste when we step outside. Apparently my brother took their fleeing as a challenge. He chased a group of deer through our backyard and into the neighboring woods and if you ask him, “I almost touched one.” He admittedly didn’t know what he would have done with an entire live deer, but he knew he’d figure it out in the moment. Classic.

Sometimes deer biologists need to catch deer and needless to say, my brother’s methods are not the most effective. Instead, they use clover traps, rocket nets, and dart guns to safely capture live deer and conduct research. Reasons for catching live deer include deploying GPS or radio collars to track movements and survival, collecting blood, inserting individual identification tags, and to help answer a variety of other research questions.

Clover Traps

Clover traps are rectangular, netted traps with a door that closes when a trip wire is triggered by the deer. The traps are baited with corn behind the trip wire. The trip wire is high enough that critters like squirrels, raccoons, and birds can enter and exit the trap without getting caught. Researchers check clover traps at least once daily. If there is a deer inside, they open the door, pull it out, and process the deer in whatever way is relevant to the specific project. Some clover traps are designed so that researchers can collapse the trap on the deer when they arrive, helping immobilize the deer while they remove it from the trap.

Researchers with the Missouri Deer Project remove and process a captured deer from a clover trap.

Rocket Nets

Rocket nets are used to capture a variety of wildlife, including wild turkeys, waterfowl, and deer. A rocket net set-up consists of rockets, or cylindrical tubes with a series of holes on the back end, tied to the front end of a large net. Rocket charges (black powder) inside the rockets are connected to a long wire that links all rockets in the series. The far end of the long wire connects to a detonator in a waiting researcher’s hands. Deer are attracted to a bait site in front of the net. When the rockets are deployed, they soar over the deer, pulling the net with them. Heavy anchors on the back end of the large net prevent the rockets from pulling the net completely over and beyond the deer. The tug from the anchors causes the rockets to drop and the net entraps the deer. Researchers waiting nearby race to the rocket net site and rapidly untangle and process the deer according to the project objectives.

Researchers with the Missouri Deer Project deploy a rocket net to trap a doe.

Dart Guns

Dart guns are exactly what they sound like—guns that shoot darts. The darts are filled with an immobilization drug, which varies by species and project, though there are guidelines, regulations, and approval processes governing how immobilization drugs can be used. When a deer is shot with a dart gun, ideally in a meaty part of the body like the ham, the drug releases into the deer. Researchers process darted deer while they are chemically immobilized and reverse the drug before letting the deer go on its way. Researchers use dart guns from tree stands over baited sites or even while driving around in a truck, so long as the deer will stand in range of the dart gun. Like other guns, dart guns must be cleaned and sighted in regularly to ensure accuracy.

I got the opportunity to practice with several dart gun models while learning to safely immobilize wild animals at a Safe-Capture workshop.

I got the opportunity to practice with several dart gun models while learning to safely immobilize wild animals at a Safe-Capture workshop.

These methods tend to be the most common in North Carolina and Missouri where I am familiar with deer research. Other states may deploy different methods to catch deer, however. Drop nets rest on poles above a bait site and fall at the will of the researcher when deer are present. Box traps are like a fully enclosed clover trap. In areas with long swaths of open ground without timber, some research projects hire helicopters to find and capture deer using a net gun. Regardless of the capture method, research allows state and federal agencies to better manage our deer herds. With a thriving deer population, nature enthusiasts from hunters to adorable animal lovers (to backyard deer chasers) will enjoy their presence for years to come.