Food Habits of a Re-Introduced River Otter (Lontra canadensis) Population in Western New York-Annual Diet, Temporal and Spatial Variation in Diet and Prey Selection Conclusions: A Thesis by Melissa Skyer
You may have learned in another recent post, Scat Happens, about the importance of scat in researching otters. The thesis research of Melissa Skyer at the Rochester Institute of Technology, Food Habits of a Re-Introduced River Otter (Lontra canadensis) Population in Western New York-Annual Diet, Temporal and Spatial Variation in Diet and Prey Selection Conclusions, used scat to determine the types of prey items being eaten by the re-introduced river otters from the New York River Otter Project. Skyer filtered scat samples through a filter small enough to retain fish scales and crayfish parts.
Pumpkin Seed Sunfish (Photo from Ohio.gov)
Skyer was able to determine crayfish sizes (by measuring claw size), fish type (by identifying scales), and fish age (by looking at the annual growth rings on the scales). The scales were analyzed underneath a microscope in order to determine their identity and age.
After analyzing 71 scat samples from 3 different creeks within Monroe County, New York Skyer determined that sunfish was the most common fish found in otter scat, followed by carp and brown trout. Crayfish was also a common food item, occurring in 54% of the scat samples.
Photo by David Coon
What is interesting about this research is there is often concern that otters will be competing with fisherman for game fish. However, because Skyer was able to determine prey type and size, it appears that otters are eating smaller sunfish, crayfish and carp. None of which are highly sought after by game fisherman. Some research even shows that otters may benefit fisherman by eating the smaller fish that compete with larger game fish.
Also, based on the prey analysis of other successful otter re-introduction projects we are seeing similar patterns in the otters released in Western New York. Therefore, this implies that the otters here have enough prey and the appropriate types of prey items to maintain healthy populations!
So there you have it, just one more example of the importance of scat!
