Cyanide on the Landscape: the M-44 is Back

It’s not smart to leave cyanide lying around on public land. Cyanide is a potent toxin that, in small amounts (i.e., <1 g), causes lightheadedness, giddiness, and rapid breathing, progressing to stupor, coma, spasms, and convulsions.  Symptoms of acute sodium cyanide poisoning develop rapidly.  In one published study from the 1980s that was performed by U. S. Fish and Wildlife Service personnel using penned dogs and coyotes, symptoms developed at 32 seconds.  Animals died within two minutes of exposure. 

Sodium cyanide is registered as a restricted-use pesticide by the EPA. It is currently delivered to coyotes and other animals via a metal spring-loaded ejection device called an M-44 (colloquially called a “cyanide bomb”) that was developed by the U.S. Department of Agriculture’s Wildlife Services. In addition to coyotes, targeted species include red and gray foxes, and stray dogs, all of which are considered a threat to commercial sheep flocks. The metal rod portion of the M-44 is inserted into the ground, leaving the cyanide-loaded tip exposed.  They are smeared with scents that are attractive to canids. The protruding tips are sometimes confused with irrigation sprinklers or surveyors’ stakes, tempting puzzled hikers to touch them. 

The M-44 and its components are manufactured at the Pocatello Supply Depot (PSD) in Pocatello, ID, a division of Wildlife Services.  In addition to <1 g of sodium cyanide, each capsule contains one of several fluorescent marker powders. The latter are used so that Wildlife Services personnel can determine whether a coyote or dog was killed as part of a Wildlife Services program, or by a commercial applicator.

Wildlife Services promotes the use of M-44s because they are considered specific for coyotes. When a coyote is killed by a cyanide device, other animals that feed on the carcass are not at risk of being poisoned because the cyanide gas dissipates quickly and doesn't linger in the body.  The metal device is robust and reusable over multiple years.  The cyanide in capsules is cheap to manufacture. One Wildlife Services M-44 factsheet makes the extraordinary claim that animals killed by sodium cyanide show no overt signs of distress or pain. While death is comparatively swift, I am unaware of any owner who claimed their convulsing dog passed easily from this world.

An M-44 “cyanide bomb”. Image credit: Trap Free New Mexico

As the design and use of the M-44 was modified over the years, the number of dogs killed (per Wildlife Services records) declined. Between 1997 and 1999, the official annual tally was above 200.  Since 2010, the annual number has been between 17 and 40. The numbers are conservative and likely an undercount.

M-44s have killed Wyoming dogs.  In March 2017, two dogs were exposed to cyanide while their owners hiked what they thought was Bureau of Land Management (BLM) land some 50 miles north of Casper. Both dogs died within minutes.  It is likely that the owners strayed inadvertently onto unmarked private land. At that time the coordinator for predator management in the Wyoming Department of Agriculture estimated that “about 300” M-44s were deployed annually on public and private land across the state.  The department runs a training program in the use of M-44s so that users are officially certified. 

In response to public pressure, the EPA established 27 restrictions on how M-44s can be used.  They can only be set on or within 7 miles of a ranch unit or allotment where predation on livestock by coyotes was documented recently.  They cannot be set on federal lands formally set aside for recreational use.  Gate signs must be posted near the pasture.  Smaller stake signs are placed in the pasture.  At least, those are the official requirements.  The owners of the two dogs killed north of Casper looked for but could not find any warning signs.  As often occurs in Wyoming, the boundary between BLM and private land was unmarked.

Canyon Mansfield and Kasey. Image credit: East Idaho News.

For decades, going back to the Nixon administration, use of M-44s seesawed between legal use and being banned.  The most recent cycle started in 2023, when the Biden administration prohibited use of M-44s on all BLM-managed lands for five years.  This was due in part to publicity surrounding the injury of a 14-year-old boy in Idaho, after he encountered an M-44 set close to his family home. His dog, Kasey, died, and the boy had medical sequelae following cyanide exposure. Canyon likely survived only due to the favorable wind direction. The government responded that the negligence by Wildlife Services employees was outweighed by the negligence of Canyon and his family.

As it happened, his father was a family physician. Public awareness of these devices increased. In May 2026, a memorandum of understanding was signed between the BLM and Wildlife Services. It supersedes the Biden policy from 2023.  Written in opaque bureaucratese, it lifted the ban on M-44s.  The memo was spotted by Public Domain, an investigative group that publishes on Substack. Interestingly, a spokeswoman for Interior later claimed that the memo “does not itself authorize or expand use of M‑44s.” 

But dollars to doughnuts the table is set.

What is odd is that there are multiple, safer ways to control coyotes.  Some, like sheep guard dogs, do not require killing or poison. Other options that are already used: tax-subsidized Wildlife Services shooters in fixed-wing airplanes and helicopters; private contractors using guns, snares and leghold traps; yote-mashing; coyote killing contests.  The Wyoming Outdoorsmen organization offers a $25 bounty for a killed coyote.  Currently the state of Wyoming invests $4.8M a year in predator control, much of it directed at coyotes. Official Wildlife Services reports show that agency operations remove between 4,500 and 6,500 coyotes annually. In addition to government-funded removals, private hunters and recreational shooting are believed to account for thousands more coyote kills per year.

There are two enormous problems with the use of M-44s. 

• One is that they discharge a lethal, fast-acting toxin. If you or your dog is sprayed in the face with the cyanide dust, death is likely. Wildlife Services claims that M-44s have never resulted in a human fatality. But close calls are not rare.  According to an investigative report by the Sacramento Bee in 2014, over the previous 25 years at least 18 Wildlife Services employees and several private citizens have been injured by the M-44 device. 

• The other problem is the indiscriminate nature of M-44s.  In a detailed letter written to Wildlife Services by a large group of conservation and wildlife advocacy organizations, it was estimated that M-44s killed more than 50,000 members of more than 150 non-target species between 2000 and 2017.  These included federally- and/or state-protected animals such as Mexican gray wolves, grizzly bears, kangaroo rats, eagles, falcons, California condors, red-tailed hawks, great horned owls, armadillos, pronghorns, porcupines, long-tailed weasels, javelinas, marmots, snapping turtles, turkey vultures, great blue herons, ruddy ducks, sandhill cranes, and ringtail cats.

While I recognize that killing coyotes is a handy taxpayer subsidy to federal and private trappers in Wyoming, we do not need cyanide on the landscape.

They need to be banned, once and for all.