Kym Kemp / @ 10:57 a.m. / Marijuana and/or Cannabis , Nature, wildlife

Protecting Pot (and Other Plants) Without Using Rodenticides


The above video shows a fisher that scientists suspect was poisoned by rodenticides. According to the Youtube caption, “This fisher had four different anticoagulant rodenticides in its tissues: three SGARs (second generation anticoagulant rodenticide) and one first-generation rodenticide.”

Recent studies have tied the deaths of wildlife to the use of rodenticides (poisons used to kill rats, mice, etc.) The rodents eat the toxicants, become ill, then can more easily be caught and consumed by predators.  Then those predators—hawks, owls, bob cats, etc.—in turn get poisoned.

One northern California study posited that marijuana grows on public lands have especially impacted fishers (a cat sized carnivore that is a candidate for Endangered status) because some growers bring large amounts of these products into remote areas where the fishers live. Besides the distance from traditional sources of the toxicants (agriculture lands or urban settings,) the reasons that the study authors believe marijuana grows to be a source of the animals’ exposure are the facts that large amounts of these products have been found at remote grows and most of the fisher deaths occurred during the spring when growers must protect their young plants from rats and mice. 

Not only wildlife but an estimated 10,000 children a year are exposed to the rodenticides. In fact, the EPA has moved to ban some products because of the danger to both children and wildlife. 

As the understanding of the role of rodenticide in poisoning spreads, there has been a backlash against the products. The anti-rodenticide movement is gaining momentum in Humboldt.  It began in Southern Humboldt where several stores have begun removing rodenticides from their shelves. The Humboldt Co. Supervisors recently unanimously voted for a resolution to urging businesses to “stop the sale of all products containing” one of ten rodenticides.

There are several groups working to bring awareness of the problem. Raptors Are the Solution is a national organization that has local support. A local Facebook Group, Friends Don’t Let Friends Use Rat Poison, has over 200 members. 

LoCO interviewed a member of that Facebook Group who has extensive experience with gardening and dealing with rodents without using rodenticides. Uti, as he is known, provided photos and detailed instructions on protecting young plants from rats without using chemicals.

The interview:

1. What makes you interested in rodenticide use? 

My interest in rodenticides probably started when I first read about the poisoning of pets that ate mice who had consumed the first generation anti-coagulant d-Con in the 1990s. I had two indoor-outdoor cats who were very good mousers and I also had an abundance mice in my garage and workshop, so I didn’t want to risk harming beloved pets. 

Fast forwarding to 2010, my awareness was again piqued when I read an alarming news story on a mortality study done of owls in British Columbia in 2009 that proved the new generation super toxic anti-coagulant rodenticides were wiping out the owls all over western Canada… . 

Five years ago I moved to small cabin on a ridge-top in the Mattole watershed overlooking the King Range. One of the things I loved about the remote location was the diversity of wildlife I was seeing; much more than at my first home near Garberville. 

I’m a toolhead, I make my living doing carpentry, plumbing, alternative energy work—-whatever building and repair skills people need to keep a homestead going out in the hills, and often I am driving home at dusk, so I see lots of nocturnal critters as they begin their active period. I’ve seen everything from mountain lions to my only sighting in Humboldt of a pair of rare Pacific Fishers crossing the road a few hundred yards from my driveway. 

I loved it that there were so many owls in the area.  I’d see them fluttering through my truck’s headlights on the road almost daily. Owls regularly hunted around my cabin feasting on the mice that inhabit my wood shed. But over the past five year period of time, my owl sightings have dropped off. This is just an anecdotal connection, but my decreasing owl sightings have coincided with the Green Rush. The expansion of cannabis cultivation from the small mom and pop grows hoping to avoid detection by the CAMP helicopters, to the mega grows visible to the world via satellite imagery on Google Earth, those grows that marijuana critics have been so vociferous about. My neighborhood is no different than many others in the Emerald Triangle. The grow scenes around me are expanding at a fast pace.   

2.Tell me about the ill effects of rodenticides. What made you first aware of the problem? 

In the past 2 years I could tell that the expanding cannabis cultivation in the hills was increasing the use of rodenticides because the shelves at the gardening suppliers in town were being stocked with more and more of the two common classes of rodenticides: the anti-coagulants like the d-Con brand products and the Bromethalin type neurotoxins. And evident weren’t just the little homeowner boxes of bait pellet trays—-I was seeing big two hundred dollar plastic pails of the chunk type of poison bait that were stacked in the aisle of one well known Southern Humboldt supplier. They were selling poisons that had fish scent added—-goodbye bears! Almost everyone was selling it in Southern Humboldt, seemingly oblivious to the disastrous consequences for the wildlife.  

As a medical user of cannabis and someone who has worked in the hills for 17 years, I’ve learned enough about marijuana cultivation to know that gophers and wood rats can do some serious damage to marijuana plants. Wood rats love fresh, tender, juicy greens and other rodents will peel the bark off the plant trunks, presumably to eat the nutritious cambium layer, much the same way beavers and porcupines do.   

Cannabis farmers are just like any other farmer or rancher: the loss of plants means less product at harvest time and pot farmers don’t like that anymore than a rancher who loses calves or lambs to predators. Both groups tend to declare a holy war on what they see as an enemy taking a bite out of their wallets.  

The cannabis growers have turned to the chemical industry to solve their problem with poisons because it’s a whole lot less work to toss out some chunks or packets of  rat poison than it is to maintain a trap line around the perimeter of the garden. The unintended consequence of that is secondary poisoning of the very species that are a grower’s allies—-the rodent predators.  

Here’s a list off the top of my head of the wild animals in our area that eat rodents and are susceptible to secondary rodenticide poisoning: Mountain Lions, Bears, Bobcats, Coyotes, Foxes, Hawks and other raptors, Owls, Fishers, Martens (extremely rare), Weasels, Mink, several species of snakes, Skunks, Raccoons and Ringtail Cats. Scavengers that will eat dead rodents are: Ravens, Crows, Vultures and Opossums. 

Wood rats are hard-working food harvesters. In Humboldt we have the Dusky Footed and the Bushy Tailed species here. The Duskies build lodges much like beavers do and then cache food in them. They collect and store fresh greens, acorns, nuts, seeds, berries, fruits and fungi. When you walk in the woods you’ll see their handiwork as they construct their lodges from piles of sticks, leaves and woody debris placed over stumps, shrubs or in tree crotches or low limbs.   

Unfortunately these rats will even harvest the poison rodent bait from homesteads and gardens and store it for later consumption. I’ve seen it in their nests. Although d-CON proudly claims their second generation product will kill with one feeding,  the process is still slow enough that poisoned rodents continue to move about, disoriented and even more vulnerable to predation. Please remember that d-Con’s manufacturer is oriented to the urban, suburban and agricultural storage markets and whatever research they have done has probably been with different species that have different habits than wildland rodents.  

Wildlife poisoning by rodenticides has been publicly documented by the E.P.A. as far back as 2004 and a major memorandum warning of the dangers of secondary poisoning of wildlife was issued in 2006 by their biologist, Bill Erickson, who had surveyed hundreds of cases in the U. S. Coupling that with verified pet and human accidental poisonings, one would think that the government would restrict the use or ban the stuff. The E.P.A. is trying, but politics and fear mongering by the poison makers have postponed the regulation and banning of certain rodenticides. I’m not surprised, given that rodent poison production is a multibillion dollar industry.

A good example of the fear mongering is the letter that Reckitt-Benckiser, the makers of d-Con, sent to the Humboldt Board of Supervisors on May 14, 2013, the day they unanimously approved a resolution asking Humboldt County retailers to stop selling certain rat poisons. In that letter, RB’s representative warned the Supervisors of public health consequences should their product be taken off local shelves. I really think RB’s primary concern is with their 10 billion in worldwide profits drying up. Feigning concern for our public health, while ignoring the overall health of our environment is rather disingenuous. 

I’ll give you a quick example of how devastating secondary rodenticide poisoning is.  A pair of nesting barn owls will consume up to 2,000 rodents a year feeding themselves and their young according to field studies of the owls. Those owls are very valuable friends, helping to manage the rodent populations around a homestead, farm or ranch. They work for free, so who in their right mind would poison them? The resulting rodent population bomb is shocking when you do the math on how many offspring  that many rodents can produce in a year.  

3. Do you have advice for growers/gardeners/home owners with rodent problems?  

First of all stop using any type of rodenticide immediately. They all have negative consequences. By using poisons you’re not decreasing the rodent population, you’re actually increasing it in the long run by damaging the natural rodent predators who want them for food as much as you want them out of your space. Rodents, because of their fecund nature will always be able to out-breed our attempts to exterminate them. I admit it is different in an urban or suburban environment because wild rodent predators don’t live there in meaningful numbers and rodents thrive without natural controls. It’s a problem as old as human civilization—-wherever humans go the rodents follow. Even in urban and suburban settings the poisons still do unintended harm to pets and people through accidental poisoning, especially babies with a less developed sense of taste. The EPA says 10,000 children are poisoned every year by rodenticides in this country and some of them die. 

If you have rodents in your living space the best way to get rid of them is to block their access points from outdoors and keep food and nesting materials away from them.  It does little good to poison or trap them because more rodents will return via the same entry points. The number one household rodent entry point I see in my construction and repair work is where pipes and ducts penetrate walls and floors because the plumber, heating contractor or carpenter did a sloppy job cutting the hole too large and didn’t seal up the gap, especially the drain pipe under the kitchen sink. That’s why you find evidence of them in your lower kitchen cabinets and drawers. The rodents use the pipe exterior as a highway to get into your home. 

If you have gopher problems in your yard or garden, protect the bases of your plants with wire mesh.  Use the wire mesh baskets to surround the root ball if necessary.  I personally have seen little damage from mice and voles in a cannabis garden, but I do know voles eat green vegetation. 

If you’re in the Northern California area get a copy of “Best Management Practices: Northern California Farmer’s Guide”. There are excellent suggestions for improving your gardening practices overall and help in dealing with rodent problems. I only have one small issue with the information in the Guide’s section on rodent control and that is the suggestion that rodents are mainly seeking water, so leave some containers accessible to them. That may be partially true, but it ignores the biology of  wood rats—-they harvest and eat fresh green vegetation and they love marijuana.

4. How is the campaign to get people to use other means than rodenticide to control their pests going? How have local shops responded? What steps are being taken?  

There’s been a local campaign going on that started on Facebook last year. Penelope Andrew created an open group called “Friends Don’t Let Friends Use Rat Poison” to share information and ideas on how to deal with the poison issue.  Starting last year after the UC Davis study on Pacific Fisher poisoning deaths being linked to pot growing practices was published, there has been a lot of negative press regionally and nationally about the use of rat poisons in Northern California marijuana cultivation and lots of hysterical accusations characterizing growers as being greedy and irresponsible outlaws.

If anyone has read Kym’s Blog posts on that study and the blog post about Google Earth’s graphic revelations of mega grow sites, you know how vehement and negative hundreds of comments have been. It makes it very hard for groups who are trying to promote clean and green and other environmentally responsible marijuana cultivation practices to operate in a constructive manner to shift the industry towards sustainability. The sensationalized negative press tends create a public perception that lumps everyone involved into negative stereotypes.  As soon as you post anything concerning marijuana cultivation on blogs BAM!!!, down come the hammers from the local internet trolls stifling intelligent and constructive discourse. 

So the Green Rush is fast creating something of a runaway negative image.  One of the way to start doing something to counter that image, I thought, was to educate the local gardening product suppliers, and to that end, I surveyed every retail source of rodenticide sales in Southern Humboldt county. Only two local businesses I found did not sell rat poisons at that time: Whitethorn Construction and Humboldt Hydroponics.  After my survey, I posted a list of the business owner’s and manager’s names and addresses on the Facebook group’s page so that people could write letters expressing their concerns.  

I wrote my own letters and included reprints of news articles on the rodenticide wildlife poisoning issue. I only got one reply, and that was from Steve Dazey, and it was very positive. He told me when he read my letter and the reprints I sent, he knew immediately that Dazey’s would stop selling rat poisons, but he waited until he held a staff meeting to discuss the issue. By a consensus decision making process, they pulled all the poisons off their shelves at Dazey’s.

Furthermore, during that time, Steve and some of his staff were attending a trade show and I notice that they added some other non-poisonous rodent control products to their shelves. The good news continued this spring when the other major gardening supply shops, Sylvandale Gardens and Redway Feed, pulled their stocks of rodenticides and upped their stocks of traps.  That left the two grocery stores and the two hardware stores as the only suppliers of rat poison in Southern Humboldt.  The grocery stores and one of the hardware stores carry a limited supply of d-Con, but I’m still working on the fourth business that carries way too many rodent poisons and not enough non-toxic choices in my opinion. 

5. Tell about your observations of rats. 

First of all let me say that wood rats are pretty cool animals. They’re nothing like their ugly cousins the city rats. Some people go so far as to call wood rats cute and personable. Unfortunately, a nice well irrigated green patch of cannabis in their territory is too big a temptation for them to pass up. It’s summer, it’s dry and the native plants are tough and not too juicy; they are trying to conserve moisture until the rains return in the fall. If you’re a pot grower and you have tasted your plant’s leaves you know they are juicy and edible. (They might not be as tasty as spinach, but they do taste like——well, medicine. I juice them and add the juice to my smoothies for their non-psychoactive health benefits. I highly recommend it.) 

The wood rat versus marijuana farmer discord is nothing new. Ever since humans began cultivating crops ten thousand years ago they have been in conflict with the wildlife around their plants. The same thing applies to the domestication of livestock—-an African lion sees a Masai tribesman’s cow as an easier meal than an antelope. It’s not personal for the animals, but humans take great offense and usually win the competition to keep most of what they grow for themselves by eliminating the wildlife. It’s not personal with wood rats either; they’re just following their biological imperatives.  

A cannabis grower has a few choices in the wood rat conflict, each having greater or lesser degrees of harm. If they have big mega grow scenes, they can ignore the wood rats and lose a few plants, but save on labor and the expenses of dealing with the rats. Or they can get ugly about it and scorch the whole local environment with expensive poisons, as has been documented. Or they can put their effort into being a good neighbor by fencing their gardens well with deer/rabbit wire to prevent small non-climbing animals, like rabbits who will feast on cannabis, from passing through the lower fence wire and by setting baited kill traps around the garden perimeter.

Quality kill traps cost about 3 bucks locally and they will last for many growing seasons. Putting out a trap line is a little more labor intensive because you need to check on it frequently to remove any dead rodents and then re-bait. The traps are very effective, but the downside of traps set in the open is that there is a chance other animals and birds will be caught. I’ve never seen it happen, but friends involved with wildlife rescue and rehabilitation say lots of birds and other small animals show up at their centers who have been injured by kill traps. To help prevent that, you can make or buy kill trap covers to keep some of the other wildlife from getting caught in a kill trap.  A simple open ended box made of scrap lumber or a recycled plastic pot turned upside down over a trap with entrance openings cut in the rim will keep most everything from getting killed or injured. The exception would be raccoons and opossums, who can climb a fence and are dexterous enough to get past simple covers.   

Even more environmentally friendly and compassionate are the no-kill Havahart type traps. Wood rats can grow up to 17 inches long, head plus tail, so a wood rat size trap costs around 26 dollars, but it lasts practically forever. The Havahart X-Small one door model 0745 is a good size for wood rats. Using a live trap to catch and relocate wood rats means you must commit to going out early every morning, checking your traps and immediately relocating the rats. Why? Because once caught the rats get stressed out and I’ve seen them die in live traps from stress or lack of food and water. They’re mostly nocturnal and being out in the open daylight freaks them out. Wood rats have fairly large territories depending on their sex and the local habitat, up to 12 acres according to some researchers, so you need to take them far away before releasing them. But for everyone’s sake don’t release them near someone’s home or garden. 

Here’s some good news about wood rats. They are strongly territorial and mostly solitary, except when breeding and during the rearing of young. Once you trap one or two adults or the juveniles you may not see another for the rest of the growing season.  You don’t have to leave traps out all season, because once the plants get big enough all the rat is likely to harvest are the lower small limbs, so the loss of  some small buds is not going to make much of an impact. If you see evidence of wood rat harvesting later in the season, you can always put some traps back out under the plants. Just look for their signature 45 degree angled cut on the remaining limb. (See photo below.) 

This time of the year, mid-May to early June, is when cannabis starts are most vulnerable to rats and gophers. A wood rat can cut a whole small start from its tender stalk in one clean bite. A gopher will just pull it down into its tunnel.  The photo below shows what it looks like when a wood rat takes a small 16” tall marijuana start. The rat makes a clean cut through the stem at a distinctive 45 degree angle. Once the plants are well established the rats will prune off the lower limbs. After they harvest a plant or branch they will drag it off to their nest, store it and return for more. If you delay protecting your plants from the time of transplanting like this person did, be prepared to replant starts.

 

 

6. Anything else you would like to make sure is covered in the story?

First a warning: If you’re sensitive to the graphic details of killing rats, skip this [final part.] 

Let me add a few tips and photo illustrations for those who chose to use kill traps and are new to their use, or who have had poor results in the past.  Wood Rats are very strong and robust animals. They can weigh up to 12 ounces. Don’t use  some of the flimsier traps designed for urban rats. The all-plastic T Rex trap seems too weak to me for quick clean kills of wood rats and they cost around 10 dollars each, I’d rather have 3 Victors. My personal favorite is the standard Victor model because it has a stronger spring and lasts longer than the cheaper copycat Tomcat brand. The base is high grade certified sustainably harvested wood and won’t warp. You don’t need the more expensive professional model with the yellow plastic bait pedal. The trap in the photo has been used for 3 years and still works perfectly.  Pardon the gory reference, but if a kill makes a bloody mess just scrub it with something like citrus cleaner, rinse it and let it dry in the sun. Do that outdoors and wear disposable gloves. Rats don’t seem to mind if any remaining scent of their deceased kin is on a trap. 

To get started, unwrap a new trap and remove the staple that holds the long trigger rod to the wooden base. Take a pair of needle nose pliers and bend the triangular prong on the bait pedal upwards to help hold the bait more securely (see photo)

 

 

The big problem with rat traps is that small rodents will often steal the bait off the flat metal bait pedal. Here’s a technique I’ve used with great results that keeps the bait from being stolen or lost when the trap springs closed. I call it a “bait burrito”.  

Wood rat bait can be as simple as crunchy peanut or almond butter. It needs to be a little thick, not runny. Seeds and nuts are part of a wood rat’s natural diet, so I believe they won’t pass up the tasty higher calories of the nut or seed butter bait. I didn’t have any commercial nut butter for the photo, so I used what was in my kitchen and coarsely ground up a few pumpkin and sunflower seeds, a little shredded coconut with a few raisins, using vegetable oil to hold it together—-sounds like a people power bar. Store your leftover bait in a small container in the fridge. For the bait burrito wrapper I used a leftover scrap of mosquito netting, but cheesecloth or any pliable open mesh cloth is fine. Roll up a small ball of bait and center it on the fabric.  (See photo)

 

 

 

 

Next, fold the sides in and roll the fabric around the bait ball just like a burrito with the ends tucked in. Fasten it to the bait pedal of the trap with some wraps of fine wire, or heavy thread. That’s it. You’re ready to arm the trap as usual.  This method prevents the bait from being stolen and the rats will try to tug on it springing the trap.

Occasionally, you will also catch a large mouse. Remember to remove the rodents with disposable gloves. The bait burrito stays on the trap and you won’t need to re-bait it every time. Just rearm it. (See photo)

 

 

 

 

 

 

 


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