"In marijuana cultivation sites, regulations regarding proper use of pesticides are completely ignored and multiple compounds are used to target any and all threats to the crop, including compounds illegal in the U.S.," she says.
While some fishers have died from either directly consuming flavored rodenticides or by consuming prey that had recently ingested the poisons, exposure may also predispose animals to dying from other causes. Exposure to lower dosesor to combinationsof the poisons, results in slower reflexes, reduced ability to heal from injuries, and neurological impairment. Consequently, this leads to death from other sources, such as predation or road kill.
Fishers in the southern Sierra Nevada are highly susceptible to pesticide exposure because, unlike their larger bodied relatives in other parts of the country that eat larger prey, their diet consists of small mammals, birds, carrion, insects, fungi, and other plant material. In the vicinity of illegal marijuana sites, numerous dead or dying insects and small mammals are often found. In this study, scientists reported on the amount of poisons found at over 300 illegal plots and compared the locations of these sites with the home ranges and survival of 46 adult female fishers.
The conservation implications of this study are far-reaching.
"By increasing the number of animals that die from supposedly natural causes, these pesticides may be tipping the balance of recovery for fishers" says Dr. Craig Thompson, a PSW wildlife ecologist and the study's lead author.
This new threat may also impact other species already facing declining populations, including the wolverine, marten, great gray owl, California spotted owl, and Sierra Nevada red fox, which may also be exposed to the poisons, say the scientists.
|Contact: Sherri Eng|
USDA Forest Service - Pacific Southwest Research Station