Coastal Martens: ‘A Cog in the Ecosystem’s Machinery’

Recently, we reached out to Dr. Mourad Gabriel, a conservation ecologist who has spent the past decade studying several forest carnivores, including fishers and martens. During our interview we discussed the threats to the coastal marten, a rare carnivore that Earthjustice is currently fighting to protect under the Endangered Species Act. With fewer than 100 individual coastal martens remaining in California, the survival of the species is uncertain. However, Gabriel believes that with all the recent attention and focus on the species and the challenges it faces—from natural predation to vehicle strikes to illegal marijuana farms—there is still reason for hope.

Q: What does your research on coastal martens focus on? 

A: We’re looking at two things. The first is the health aspect—determining what pathogens martens are exposed to or what potential infectious or non-infectious diseases that they may have died from.

The other aspect is looking at the martens’ predators. When martens die, their carcasses are submitted to our research organization to determine the cause of death. There, we investigate the genetic material that is left behind in the bite wounds of the predators, or in the claws and teeth of the martens.

Q: Why are martens important to the ecosystem?

A: They can be a flagship species for a specific issue, but also, just like any carnivore or any species that is part of an ecosystem, they are a cog in the ecosystem’s machinery. So if you remove that particular cog, that machine is not going to be a well-oiled, functioning machine. And if it’s a significant cog in the machinery, for example if a species like the marten is high up on the food web, removing them may create a significant issue in maintaining a healthy and balanced ecosystem.

Q: What is the most surprising thing you’ve seen while observing martens?

A: One time I had the very fortunate experience of seeing a female marten move her kits from one den site to another. I saw the female marten carrying a kit in her mouth, moving the kit through the forest floor a couple meters from me, take her kit to a specific area, and then drop it off. She then came back to grab the second kit and move that kit to where the first kit had been.

Q: You were also surprised to find a link between forest carnivore deaths and marijuana cultivation, correct?

A: Yes, it is surprising that fishers died from rodenticide. Is it surprising that martens were exposed? Yes, it is very surprising that martens were exposed. These are martens that have lived in high elevation areas in California—where we would never have thought that at 5,000 to 6,000 feet in elevation there is going to be risk of a marten running into an illegal marijuana cultivation site. Now we know that there are most likely cultivation sites right in the martens’ territory, and that’s a problem because many of these sites heavily utilize chemical agents like rodenticides and other pesticides. There has not yet been a marten death directly attributed to rodenticides, but we do have martens exposed to chemicals found only at these marijuana cultivation sites.

Though the martens don’t eat these rodenticides directly, if rodenticide is placed on the ground and consumed by an invertebrate like an insect, then that insect would be exposed. If a rodent consumes that insect, then that rodent would also be exposed. If that rodent was then consumed by a marten, then that marten would be exposed. When that marten is killed and consumed by a bobcat, that bobcat is then exposed, and when that bobcat dies the turkey vulture or the carrion eater that consumes that bobcat will then be exposed. So you can see the chain of events.

Q: Does that mean that rodenticide could eventually work its way all the way up the food chain to humans?

A: We’re trying to figure that out right now by investigating potential sources of exposure to community members and indigenous people near these sites. Some of these marijuana sites are on reservations where indigenous people reside and utilize their lands for hunting and fishing, and where community members utilize public lands for recreational activities.

Q:  Is anyone trying to shut down these illegal marijuana cultivation sites or at least mitigate the environmental damage?

A: Well there is an effort, but is that effort strong enough? My personal opinion is no. We should have sufficient support to conserve and preserve our public and tribal lands, and therefore individuals that reside on tribal lands should be free of trespassers who are contaminating their lands. And as owners of the public lands, we should be free of any contamination from individuals who have been utilizing public lands.

There is a lack of support for conservation officers to go out there to actually intervene and remove these threats before they take root on our public lands. And if they do take root on our public lands there is a complete lack of support to clean up these sites. We must actively remove those sites by dismantling the infrastructure so it is not possible for drug trafficking organizations to reestablish those sites, but at the same time we must also remove each toxicant present so it doesn’t pose a risk to wildlife, fisheries or humans.

Q: Since you discovered the ecological impacts of illegal marijuana cultivation, you’ve faced some backlash, including an incident in 2014 in which your dog was poisoned. Have you faced any more backlash or intimidation as you’ve continued this research?

A: In all honesty, I do not know, and the reason why is because I choose to ignore it because intimidation should never been in the same sentence with science gathering. That said, I am aware, I’m vigilant, and I do have law enforcement actively ensuring that the science is gathered safely, but it is not going to hinder the collection of any data.  

Q: How many of these illegal cultivation sites are we aware of on California public lands?

A: It’s in the thousands, and those are only the ones that we are aware of. Every year a very small fraction of sites are cleaned up. Each and every year we are slowly—wildlife, humans, fisheries—being buried under a mountain of grow sites.

Q: With the coastal marten population estimated to be below 100 individuals, what are your thoughts on the future of this species?

A: Populations that are small and isolated from other populations are always at risk. But we need to think about the additive risk. The additive mortality that occurs—mortality that is non-natural, like rodenticides from marijuana cultivation or vehicular strikes—needs to be addressed. When you have small, isolated populations, any additional mortality is not beneficial to that population.

But the great thing is that there is awareness. I’m a very optimistic person and I don’t like to dabble in pessimism. Being an optimist, the more information that we disseminate out there is essential to change things in a positive direction. So whether through further dissemination of scientific evidence, peer reviewed publications, outreach through presentations or media avenues, it’s all positive.