“Anything about an otter’s body plays a big role in its success in the environment,” says Zollner. “From their thick, water-resistant fur to the shape of their bodies, they are designed to move through water and catch prey. It is a high level predator.
“My old doctorate. student, Casey Day, organized a large group of undergraduate researchers to collect data on the diet of river otters in Indiana. They used raw fecal analysis (GFA) and found that crayfish were an important part of their diet.
Otter droppings give researchers like Zollner insight into behaviors beyond eating habits. “Latrine sites are a common means of communication for many mammals,” Zollner explained. “For otters, much of this olfactory communication is associated with defecation and urination. They share information about topics such as their reproductive status and who is present nearby. Unlike visual or auditory communication, the message may be received long after an otter has left an area.
“Otter populations have increased and spread across most of the state,” Zollner noted. “Their numbers are high enough that we even have a harvest now. It is a great success. »
The feedback is so significant that researchers are looking at potential adverse effects.
“With the resurgence of the river otter population in Indiana, sport anglers have expressed growing concerns that otters could negatively impact recreational fishing,” said Erangi Heenkenda, a license holder. doctorate. student in Andrew DeWoody’s lab.
To examine the validity of the concerns and find out how much of an otter’s diet consists of sport fish, Heenkenda worked with the Indiana DNR using otter carcasses provided by trappers. Her findings helped her win an award for best student presentation at the 2021 Spring Meeting of the Indiana Chapter of the American Fisheries Society.
“We dissected otters, sequenced fish DNA from their stomach contents and matched the sequences to local fish species. Evidence indicates that game fish is a relatively small component of our sample’s diet. We were surprised by the diversity of prey fish species in otter stomachs.