Novel research approach sheds light on how midsize predators interact

Date:  February 5, 2018

Source:  Oregon State University

Summary:

A novel research approach has resulted in a key step toward better protecting the fisher, an important forest predator that findings show is the dominant small carnivore when present.

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Plan to protect weasel-like fisher cites pot risk

Oct 06, 2014 by Jeff Barnard

Citing the threat from rat poisons spread around illegal marijuana plantations, federal biologists are proposing Endangered Species Act protection for West Coast populations of the fisher, a larger cousin of the weasel.

The U.S. Fish and Wildlife Service published notice Monday in the Federal Register that it wants to list the fisher as a threatened species in Oregon, California and Washington. The full proposal coming out Tuesday also cites loss of forest habitat to wildfire, logging and urban development.

Erin Williams, who oversaw the analysis, says the poisons are regulated, but the rules have done little to stop the misuse of poisons on pot plantations in forests where fishers live.

The agency is taking public comment and having outside scientists review the proposal before making a final decision by Sept. 30, 2015.

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Pot Growers' Rat Poison Might Be Killing Vulnerable Species

Biologists in the U.S. are questioning whether rat poison used on illegal marijuana farms is inadvertently killing a vulnerable forest predator, one that is also a species of concern in B.C.

The fisher, a small weasel-like forest animal, is currently being considered for the endangered species list in the states of Washington, Oregon and California — and biologists are considering the role that outlaw marijuana plantations may have in its decline.

Mourad Gabriel, a researcher based at UC Davis, says the animal is normally a fierce predator but appears defenceless in the face of rat poison.

The toxin was found in 80 per cent of a sample of 58 dead fishers in Northern California.

"We're finding lots of chemicals out there. We're finding also banned chemicals that have been banned by Canada, United States and other nations because of the high toxicity to humans and wildlife," Gabriel said.

Gabriel suspects most of the fishers consumed the rat poison through the bodies of its prey, but some ate it directly, he said.

As other researchers have also found, Gabriel says the likely culprit is marijuana farmers using rat poison to protect their valuable crops.

Continued:  http://www.huffingtonpost.ca/2013/04/02/fisher-endangered-species-rat-poison-marijuana_n_2998585.html

Pot-grower's poison taking toll on rare fishers

Study shows that illicit rodenticide use poisoning elusive carnivore on public and community lands
August 2012. A new study shows that imperilled fisher populations are being poisoned by the use of anticoagulant rodenticides (AR) on public and community forest lands in California-probably those used illegally by marijuana growers.

The researchers looked at two distinct fisher populations: one occurring on tribal, private, and public lands in north-western California and another within the Sierra National Forest in central California. Results of necropsies showed that of 58 fishers tested, 46 of the animals (79 percent) were exposed to one or more of the toxic ARs, and four had died directly from AR toxicity.

Fishers are likely exposed to AR when eating animals that have ingested it prior. They may also be drawn to it by bacon, cheese and peanut butter "flavourizers" that manufacturers add to attract rodents. Distribution of the poisoned fishers indicated widespread contamination of fisher range in California.

Fishers in significant decline
Members of the weasel family, fishers were once widely distributed throughout North America's west coast but have incurred significant population decline and extirpation from portions of their former range. Populations inhabiting Washington, Oregon, and California have been designated a Distinct Population Segment (DPS) and declared a candidate for listing under the federal Endangered Species Act (ESA).

Study co-author and WCS Scientist Sean Matthews said, "Fishers play a vital role in the forests of the Sierra Nevada mountains and the Pacific northwest. With a body the size of a house cat and the disposition of their larger cousin, the wolverine, fishers keep forest rodent populations in check and are one of the only predators with the tenacity to regularly prey on porcupines. As fisher populations declined, they took refuge in the last remaining portions of mature forest in the Sierra Nevada and coastal mountains. Now a new threat has emerged in these remaining refuges."

Read on:  http://www.wildlifeextra.com/go/news/fisher-poison.html