Tuesday, September 22, 2015

On the Search for North American River Otters

Post contributed by Samantha, seasonal Natural Resources Technician:

Our department was able to purchase two trail cameras funded by an REI grant we received through the Saint Paul Park Conservancy in 2014. These trail cameras are being used to document the illusive wildlife found within the City of Saint Paul. Recently, our department decided to install one of the trail cameras in the Mississippi National River and Recreation Area in hopes of capturing photos of North American river otters (Lontra canadensis). To help with this endeavor, I contacted Ranger Allie with the National Park service who has been tracking river otters along the Mississippi River for a few years. Lucky for me, Ranger Allie was willing to meet me out in the field for a guided otter tracking lesson.

A land bridge used by otters.
 On a humid Tuesday morning, Ranger Allie, Emily, and I hopped into a canoe to begin tracking otters. As we canoed along the river, Ranger Allie discussed the tracking process including the living preferences and habits of river otters. Ranger Allie taught us that otters and beavers commonly cohabitate in the same areas. The reason behind this seemingly odd relationship is that beavers alter the landscape around their lodge, which benefits other semi-aquatic mammals. Also, beavers are able to break through the thick ice in the winter, which provides river otters with access to water and food. Another key point to consider when tracking river otters is that they prefer land bridges that quickly transfer them from one water body to the next.

Otter scat contains mostly fish scales.
Upon docking near a beaver lodge, we immediately came across an otter latrine with scat. The older the otter latrine, the more white in color the scat will appear due to the amount of crayfish that otters consume. In general, the makeup of otter scat is mostly fish scales. Another sign to look for when tracking otters is an area resembling a deer bed of padded down brush and grass near the shoreline. Otters tend to lay and play in these soft areas leaving behind evidence of their activity.

After surveying a couple of beaver lodges, we finally found a promising location to set up the trail camera. The area we chose was a land bridge between two water bodies. Not only was there a worn, muddy path between the bodies of water, but also semi-fresh scat containing fish scales.

Please check back to see photos of the river otters as well as learn more about the fun projects our department undertakes!

Below is a link to Ranger Allie’s trail camera footage from years past: