By Dr. Ngaio Richards, Forensics and Field Specialist
Clean water and healthy aquatic ecosystems are of immeasurable value to people and wildlife. But we need a full picture of what contaminants are circulating in our waterways and where they are originating to properly protect these ecosystems. This knowledge is currently lacking in many parts of the United States, including Montana.
Interestingly, the very wildlife that dwell and feed along rivers can tell us a lot about overall freshwater ecosystem health. Their fecal matter, or “scat” represents a rich repository of information, including exposure to contaminants in their prey and environment. With a diet abundant in aquatic organisms, river otter and mink are particularly appropriate as indicator species to help narrow down presence and sources of contaminants. The problem? They are also notoriously elusive.
That’s where Montana-based nonprofit Working Dogs for Conservation can help, because it has a superb, noninvasive monitoring tool—exuberant detection dogs—specially trained to find scat samples. Dogs are able to comprehensively and quickly cover a sizeable area and they excel at finding only the scat of the species they are trained on. This is of tremendous assistance to researchers, because visually searching for scats (even large, smelly ones) across a landscape requires a prodigious human effort. Dogs also eliminate the need to capture, handle, or mark wild animals—thereby avoiding the risks, including mortality, inherent to using such traditional wildlife study techniques.
Working Dogs for Conservation, with the aid of a Christine Stevens Wildlife Award, teamed up with our enthusiastic and inquisitive partners at the University of Montana, Colorado State Univesity-Pueblo, and University of Manitoba to find out whether heavy metals, pharmaceuticals, and flame retardants were lurking in the scats of river otter and mink, and by extension polluting our rivers. These contaminant groups were chosen because they cause a host of long-term ailments in wildlife and people.
Along with their human coworkers, two of our veteran conservation dogs, Orbee and Pepin, searched along five rivers in Montana and found hundreds of otter and mink scats where, in most cases, none or very few had been found before by humans! It wasn’t uncommon for project partners who joined us in the field to express shock over the ability of the dogs to find scat samples they had overlooked—sometimes literally right where they were standing.
In the scats analyzed to date, all the heavy metals screened for—arsenic, copper, selenium, zinc, cadmium, mercury and lead—have been detected at levels ranging from “background environmental’’ to “elevated.’’ Lead and mercury exposure in otter and mink is of special interest because of the known endocrine, neurological and reproductive repercussions. Several flame retardants were detected, as well, in some of the scats. Long-term exposure to both these contaminant groups can jeopardize aquatic ecosystem food webs, local wildlife populations, and health in adjacent human communities.
As far as we know, this is the first time that heavy metals have been detected in otter scats in North America—or ever in mink scats. It is also the first time ever that flame retardants have been found in the scat of either species. Tantalizingly, results of pharmaceutical assays are pending. We’ve also garnered interest in future noninvasive, detection dog–based otter and mink surveys—not just for contaminants monitoring, but for general ecological monitoring.
On an especially memorable day of surveying, while working with Orbee, I caught a glimpse of the glossy head of an otter emerging from the fast-moving Clark Fork River. The animal eyed us for a millisecond then disappeared downstream, with Orbee, nose pressed to the ground intent on finding his scat target, none the wiser.