An Inyo county black bear found dead during our fall ungulate captures was likely poisoned by the pesticide carbofuran. The adult black bear was spotted by our helicopter crew lying dead across irrigation piping on a top of a knoll in the John Muir Wilderness. The situation was very odd so the helicopter crew collected to carcass and flew it into base camp for a post mortem examination by the Department wildlife veterinarian. While examining the dead bear some of the biologists noted that flies which contacted the bear’s saliva or diarrhea quickly died. In light of this finding, and the likely association with what appeared to be an illegal marijuana grow, we decided to shuttle the bear carcass straight to the California Animal Health and Food Safety (CAHFS) laboratory for a full post mortem examination including necropsy and toxicological testing.
The initial necropsy findings were unremarkable. Toxicological testing detected carbofuran in stomach contents. No other carbamate or organophosphate pesticides were detected. In addition to the toxicology findings, microscopic examinations of tissues showed non-suppurative inflammation in the brain. Inflammation of this sort is typically caused by a virus, but rabies and canine distemper viruses were not detected. A cause for the encephalitis has not yet been determined and we are screening tissues for a possible gammaherpes virus that has been identified in other bears with similar brain inflammation. The significance of this finding in this bear is unknown, but was unlikely to be a contributing factor in the bear’s death. The detection of carbofuran and no other pesticides in conjunction with a decreased brain cholinesterase activity, a hallmark of organophosphate or carbamate pesticide intoxication, strongly supports carbofuran intoxication as the cause of death.
Carbofuran causes death by extreme over stimulation of the nervous system, which often ultimately leads to respiratory failure. The extreme toxicity of this material is illustrated by the fact that about approximately 64 rats or 12,000 sparrows would be killed by a single aspirin-sized tablet of the technical material. Carbofuran is one of the most toxic carbamate pesticides ever produced, and as such all legal uses of carbofuran have been banned in the United States since 2009. That’s not to say that carbofuran itself is banned in the U.S., but that there are no legal uses of carbofuran in the U.S., so for all intents and purposes it has been banned. Prior to its discontinued use in the U.S., it was responsible for losses of thousands of birds, mammals, and fish. In recent years, there have been numerous cases of illegally imported carbofuran being found on trespass marijuana grows in California and regular reports of associated wildlife losses. Some of these losses appear intentional. Carbofuran is still sold in other parts of the world, including some countries in Africa, Asia, and Latin America.
Prepared by Brandon Munk and Stella McMillin
In the Spring of 2016, CDFW (WIL and Region 6), UC Davis, BLM, USFWS, and many volunteers partnered to restore a key habitat patch utilized by the Amargosa vole. This habitat patch used to sustain the highest density of Amargosa voles in the world, but in 2010 it began to deteriorate due to changes in hydrology. The Amargosa vole team worked diligently to restore the water supply and reinvigorate vegetation growth at the marsh. Learn more about the Amargosa vole project.
Each year, the WIL oversees the rehabilitation and release of orphaned bear cubs throughout the state. With the help of non-profit wildlife rehabilitation facilities, cubs are cared for until they reach an age at which they can survive on their own in the wild.
A winter release, sometimes called a soft release, requires creating artificial dens for the cubs, encouraging them to go into hibernation. Spring releases do not require dens. Instead, the animals are released on site and hazing methods are used upon release to discourage habituation to human presence.
To learn more about the rehab and release process, check out this short video.
Researchers from CDFW – WIL, UC Davis, and USGS have been working in partnership to study how drought affects the endangered Amargosa vole. This work includes assessing the range-wide distribution of the vole and the factors which influence their distribution, continued captive breeding of the species for protection against extinction, and habitat restoration. If you would like to learn more about the project please follow the link to the CDFW drought webpage.
Recent work from Amanda Poulsen (UC Davis) in partnership with researchers at CDFW-WIL has been published in the Journal of Wildlife Diseases. This work examined the prevalence and potential impacts of toxoplasmosis in the wild Amargosa vole population. To access the paper abstract, click here.
Full reference: Amanda Poulsen, Heather Fritz, Deana L. Clifford, Patricia Conrad, Austin Roy, Elle Glueckert, and Janet Foley (2016) Prevalence and Potential Impact of Toxoplasma gondii on the Endangered Amargosa Vole (Microtus californicus scirpensis), California, USA. Journal of Wildlife Diseases In-Press.
The Wildlife Investigations Lab is monitoring pine siskins for mortality this winter. Pine siskins are a type of finch that are mostly brown in color with a bright yellow wing stripe that live in forested areas in California primarily during the winter. Pine siskins are an irruptive migrant, meaning they can be found in high densities in certain areas in some years, but often absent the next. This migration pattern is likely determined by food availability and weather conditions.
Examination of a pine siskin that died of Salmonellosis.
This winter pine siskins have been reported in numerous areas throughout California with larger concentrations occurring along the central and south coasts as well as around Redding, in northern California. Increased mortality of pine siskins has been reported in several of these areas since mid-December. The Wildlife Investigations Lab has evaluated carcasses from these locations and determined the cause of mortality to be Salmonellosis, a disease caused by Salmonella bacteria.
Salmonellosis occurs periodically in some years in pine siskins throughout their range. Previous outbreaks in California occurred during the winter of 2012-13 and in 2015. Birds become infected with Salmonella bacteria when they ingest food, water, or come into contact with objects (e.g. bird feeders, perches, soil) contaminated with feces from infected birds. Sick birds often appear weak, have labored breathing, and may sit for prolonged periods of time with fluffed or ruffled feathers. Salmonellosis is highly fatal in pine siskin, with most birds dying within 24 hours after infection.
Salmonellosis in pine siskins is almost exclusively reported from locations with bird feeders that attract increased numbers of birds. Residents can help reduce transmission of the disease by removing artificial sources of food and water (bird baths and fountains) as these may increase disease transmission between individual pine siskin, and possibly other bird species, because they bring birds into closer contact than would occur normally.
Dead birds may be reported to the Wildlife Investigations Lab to help determine locations and numbers of birds affected during this Salmonellosis outbreak.
If sick birds are observed, please contact a local licensed wildlife rehabilitation center for advice.
CDFW Wildlife Investigations Laboratory has confirmed that another turkey vulture has been poisoned by the veterinary euthanasia drug pentobarbital near Inverness, in Marin County (see map below). The massive bird with its six-foot wingspan has recovered and will be released near Inverness (Marin County) on Tuesday, August 11 at 2 p.m. Reporters who would like to see this vulture return to the wild should call 415-806-8637 Tuesday for the exact location.
CDFW confirmed pentobarbital exposure in six turkey vultures in San Rafael in 2014, but the source of the exposure remains unknown. Those birds were taken to the wildlife hospital operated by the nonprofit WildCare in San Rafael. WildCare is a CDFW-approved wildlife rehabilitator.
Wildlife officials are concerned that the July 2015 admission of an additional pentobarbital-poisoned vulture to WildCare indicates that more wildlife are at risk.
Pentobarbital is a drug used by veterinarians to euthanize companion animals, livestock and horses. If the remains of animals euthanized with pentobarbital are not properly disposed of after death, scavenging wildlife – such as turkey vultures and eagles – can be poisoned. Veterinarians and animal owners are responsible for disposing of animal remains properly by legal methods such as cremation or deep burial.
Turkey vultures are protected by the federal Migratory Bird Treaty Act and California Fish and Game Code. Euthanized remains that are not disposed-of properly are a danger to all scavenging wildlife.
CDFW asks members of the veterinary and livestock communities to share this information with colleagues, to prevent additional poisoning. WildCare also asks the public to pay attention to grounded turkey vultures and other raptors and scavengers.
Pentobarbital-poisoned birds appear to be dead. They have no reflex response and breathing can barely be detected. The birds appear intact, without wounds or obvious trauma. Anyone finding a comatose vulture should call WildCare’s 24-hour Hotline at (415) 456-SAVE (7283) immediately. Anyone with information about possible sources of pentobarbital-contaminated animals should contact the California Department of Fish and Wildlife at (916) 358-2954.
Toxicological analysis was performed by the California Animal Health and Food Safety Laboratory in Davis.