05 September 2011

Small Mammals That Excite Even A Wildlife Biologist

I apologize in advance for the poor quality of the two photos in this post, but I couldn't resist including them. Within a week's time, I saw two mammal species that made even esteemed Cardno JFNew wildlife biologist Jeremy Sheets giddy.

At a mitigation wetland at a landfill in Lake County, Indiana, I was sampling vegetation quadrats when I heard a Mallard smacking its wing against the water. I've seen Killdeer on many the occasion perform the "broken wing" routine when trying to keep a predator away from a nest, but I'd never heard of a Mallard displaying this behavior. Still, that was all that I could imagine was going on. The wing smacking continued, so I eventually walked in the direction of the noise, but the Mallard didn't leave the spot. As I got closer and the smacking stopped, I saw that the back of the Mallard's neck was covered in blood. Then I saw a small, dark mammal bound and scurry away through the several inches of water. I'd witnessed a kill! I followed in the direction that I'd seen the mammal go but I couldn't find it. Reluctantly, I went back to sampling without seeing the predator. Soon after, I heard rustling of vegetaton from the location of the dead Mallard. I snuck back over and again saw the dark mammal scurry away. I decided this time to stay close to the dead Mallard and wait to see if the culprit returned. Less than a minute later, I saw the killer, shown below.

This was my second ever live encounter with a Mink (Mustela vision), but my first encounter when I wasn't in a car. They live in areas where there is water, such as borders of lakes, marshes, streams, ditches, and ponds. Mink are omnivores, but nearly all of their food consists of other animals, and their preferred prey is Common Muskrat (Ondatra zibethicus). These dark-colored weasel relatives are also known to inhabit Common Muskrat dens and usually eventually drive these slightly larger mammals away. At this site, there were numerous Muskrats two years ago, but this year I saw only abandoned dens. Because of their typically nocturnal habits, Mink are often not observed by humans. Mink are found throughout much of North America, with the exceptions of parts of northern Canada and the southwestern United States.

My second mammal encounter occurred at a mitigation site in Superior, Wisconsin, while I was meeting with representatives from the U.S. Army Corps of Engineers and the Wisconsin Department of Natural Resources. As we were talking, the Corps of Engineers biologist saw a squirrel come out from under a parked vehicle.

This was my first ever encounter with a Franklin's Ground Squirrel (Spermophilus franklinii), a rare diurnal species restricted in range to east-central Alberta, southern Saskatchewan, and southern Manitoba south to northern Kansas, northern Illinois, and northwestern Indiana. At first, we thought we may be looking at a Gray Squirrel (Sciurus carolinensis), but this individual was smaller than a Gray Squirrel and had a gray head and gray tail with a brown body, and we later saw its burrow in the loose soil of an exposed mound of dirt. Franklin's Ground Squirrels feed on a mix of plants and animals, with green clover leaves being the primary vegetation and caterpillars and ants being the primary animals. They are found in dense grassy areas, often along railroads and on roadsides.

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