Humans changing the diet of wild American marten

By Mark Waghorn via SWNS

Humans are changing the diets of wild American marten, making them more vegetarian, according to new research.

The carnivorous mammal eats more fruit and vegetables when it lives near people.

The findings shed fresh light on the health of wild ecosystems and could boost conservation.

"Specifically, we found wild marten in relatively undisturbed environments have more carnivorous diets than martens in human-affected areas," said lead author Dr. Erin McKenne, of North Carolina State University.

About the size of a cat, they are related to weasels, ferrets and mink. The opportunistic feeder will eat anything from insects to rodents to small mammals.

They usually kill their prey with a quick, powerful bite to the back of the animal's neck.

Published in the journal PLOS ONE, the US team found gut microbiomes of marten in the pristine forest of the Huron Mountain Club in Michigan were clearly distinct from those harvested elsewhere.

"This reflects the fact marten in relatively pristine forest are able to forage at a higher trophic level, meaning they occupy a higher place in the food web," said co-lead author Dr. Diana Lafferty, of Northern Michigan University.

"In other words, the marten in relatively pristine forest have a more carnivorous diet, whereas marten in areas where there are more people were more omnivorous.

"Basically, the findings tell us a disturbed landscape results in a significantly different diet, which is reflected in their gut microbiomes."

The US team collected gut microbiome data on 16 marten caught during the trapping season and another five captured safely and released in the Huron Mountain Club.

"In conjunction with our other work on carnivore microbiomes, this finding tells us the microbial ecosystems in carnivore guts can vary significantly, reflecting a carnivore's environment," McKenney said.

"Among other things, this means we can tell how much humans are impacting an area by assessing the gut microbiomes of carnivores that live in that area – which can be done by testing wild animal feces.

"In practical terms, this work is revealing a valuable tool for assessing the health of wild ecosystems."

Marten tend to hunt at dusk and dawn when critters can be found alone. They dwell mostly in trees.

"Our goal here was to determine how, if at all, human disturbance of a landscape affects the gut microbiome of American marten that live in that landscape. And the answers here were pretty clear," Lafferty said.

Marten mark their trails with strong scent glands. They will often chase squirrels through wooded areas.

"The Huron Mountain Club is particularly important for this study, because it's relatively pristine - one of the largest, primeval forests in the eastern United States," Lafferty said.

"That makes it an excellent juxtaposition to the 16 marten that were harvested, since those were collected in regions that are more impacted by human activity."

The solitary animals can also swim and dive well. They are hunted by humans for their fur - but rarely predated on by other animals.

"It is also worth noting we were able to trap and release the marten in Huron Mountain Club during the dead of winter because we designed and built custom box traps to protect them from the elements," said co-author Chris Kailing, who worked on the project while at Northern Michigan.

"That is of interest because it makes winter sampling possible for future wildlife research even in harsh winter conditions."

Marten are extremely agile climbers - helped by a long bushy tail for balance during treetop adventures.

"This is the latest chapter in an ongoing body of research that is helping us understand carnivore gut microbiomes," McKenney said.

"Carnivore gut microbiomes are inherently more variable than the gut microbiomes of other animals.

"This study lends nuance to the emerging picture that all of this variability is not just noise.

"Rather, this variability stems from the nutritional landscape carnivores have access to - and that, in turn, reflects the health of the ecosystem carnivores inhabit.

"And that means monitoring the gut microbiome of wild carnivores can offer us real insight into the ecosystems those carnivores live in."