Pubdate: Fri, 13 Jul 2012
Source: Willits News (CA)
Copyright: 2012 Willits News
Contact:  http://www.willitsnews.com/
Details: http://www.mapinc.org/media/4085
Author: Kate Kerlin

UC Davis Research

POISONS FROM MARIJUANA GARDENS ON PUBLIC LANDS KILLING RARE FOREST CREATURES

Rat poison used on illegal marijuana farms may be sickening and 
killing the fisher, a rare forest carnivore that makes its home in 
some of the most remote areas of California, according to a team of 
researchers led UC Davis veterinary scientists.

Researchers discovered commercial rodenticide in dead fishers in 
Humboldt County near Redwood National Park and in the southern Sierra 
Nevada in and around Yosemite National Park. The study, published 
July 13 in the journal PLoS ONE, says illegal marijuana farms are a 
likely source. Some marijuana growers apply the poisons to deter a 
wide range of animals from encroaching on their crops.

Fishers in California, Oregon and Washington have been declared a 
candidate species for listing under the federal Endangered Species Act.

Fishers, a member of the weasel family, likely become exposed to the 
rat poison when eating animals that have ingested it. The fishers 
also may consume rodenticides directly, drawn by the bacon, cheese 
and peanut butter "flavorizers" that manufacturers add to the 
poisons. Other species, including martens, spotted owls, and Sierra 
Nevada red foxes, may be at risk from the poison, as well.

In addition to UCD, the study involved researchers from the nonprofit 
Integral Ecology Research Center, UC Berkeley, United States Forest 
Service, Wildlife Conservation Society, Hoopa Tribal Forestry, and 
California Department of Fish and Game.

"Our findings were very surprising since non-target poisoning from 
these chemicals is typically seen in wildlife in urban or 
agricultural settings," said lead author Mourad Gabriel, a UCD 
Veterinary Genetics Laboratory researcher and president of the 
Integral Ecology Research Center. "In California, fishers inhabit 
mature forests within the national forest, national parks, private 
industrial and tribal community lands - nowhere near urban or 
agricultural areas."

Researchers analyzed 58 fisher carcasses and discovered that 79 
percent of them had been exposed to anticoagulant rodenticides. 
Brodifacoum, a second-generation rodenticide, was found in 96 percent 
of the exposed fishers.

Second-generation rodenticides are more toxic because they can be 
lethal after a single ingestion. It can take up to seven days before 
clinical signs appear, so the poisoned animal can be a significant 
risk to predators for several days before it dies.

"I am really shocked by the number of fishers that have been exposed 
to significant levels of multiple second-generation anticoagulant 
rodenticides," said pathologist Leslie Woods of the UCD California 
Animal Health and Food Safety Laboratory System, which conducted the 
necropsies.

Anticoagulant rodenticides inhibit the ability of fishers and other 
mammals to recycle vitamin K. This creates a series of clotting and 
coagulation problems, which may lead to uncontrollable bleeding.

Exposure to the poison was high throughout the fisher populations 
studied, complicating efforts to pinpoint direct sources. The 
fishers, many of which had been radio-tracked throughout their lives, 
did not wander into urban or agricultural environments. However, 
their habitat did overlap with illegal marijuana farms.

The researchers describe a recent example in which more than 2,000 
marijuana plants were removed by law enforcement officials less than 
7.5 miles from one of the study areas. Large amounts of rodenticide 
were observed around the marijuana plants and along plastic irrigation lines.

The fisher deaths occurred between mid-April to mid-May, the optimal 
time for planting young marijuana plants outdoors - and the time when 
seedlings are especially vulnerable to pests. This is also when 
fishers are breeding and raising their young.

Gabriel said fishers may be an "umbrella" species for other forest 
carnivores. In ecology, an umbrella species is one that, if 
protected, results in protection of other species, as well.

"If fishers are at risk, these other species are most likely at risk 
because they share the same prey and the same habitat," said Gabriel. 
"Our next steps are to examine whether toxicants used at illegal 
marijuana grow sites on public lands are also indirectly impacting 
fisher populations and other forest carnivores through prey depletion."
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MAP posted-by: Jay Bergstrom