riparian brush rabbit

Deadly Disease Detected in California Wild Rabbits for the First Time

The California Department of Fish and Wildlife (CDFW), in conjunction with the California Animal Health and Food Safety Lab, San Bernardino has diagnosed Rabbit Hemorrhagic Disease (RHD) in a black-tailed jackrabbit carcass submitted from private property near Palm Springs in early May. Samples submitted to the National Veterinary Services Laboratory in Plum Island, New York, confirmed the presence of the RHD virus type 2 (RHDV2) in California for the first time. This disease is highly contagious and often lethal to both wild and domestic rabbits. The carcass that was tested was one of about 10 dead jackrabbits observed on the Palm Springs property.

RHDV2 is not related to coronavirus; it is a calicivirus that does not affect humans or domestic animals other than rabbits. At this time, no other California rabbit populations are known to be infected, but the disease has spread quickly in other states, prompting CDFW biologists to prepare for more reports in the coming months. A “quick facts” reference guide can be found on CDFW’s website.

Since March 2020, RHDV2 has caused mortalities of both wild and domestic rabbits in New Mexico, Colorado, Arizona, Texas and Mexico. Deaths of both wild rabbits and jackrabbits have occurred. Infected rabbits and jackrabbits may exhibit no symptoms leading up to their sudden death, or may suffer from fever, swelling, internal bleeding and liver necrosis. The range of susceptible species in North America is currently unknown, but all rabbit, jackrabbit, hare and pika species are likely susceptible.

CDFW Senior Wildlife Veterinarian Deana Clifford noted the introduction of RHDV2 to California could significantly impact wild rabbit populations, particularly those already at risk, such as the endangered riparian brush rabbit (Sylvilagus bachmani riparius) and those with limited distribution in the state, such as the pygmy rabbit (Brachylagus idahoensis).

“Unfortunately, we may also see impacts to species that depend on rabbits for food, as rabbits are a common prey species for many predators,” noted Dr. Clifford.

CDFW will carefully monitor the progression of RHDV2 in California, including investigating and testing rabbits found dead, monitoring populations of endangered rabbits and working with partners, including the U.S. Fish and Wildlife Service, the California Department of Food and Agriculture (CDFA) and the U.S. Department of Agriculture.

Public reports are an extremely helpful tool as wildlife veterinarians monitor the situation. CDFW is asking anyone who lives, works or recreates in wild rabbit habitat to report any sightings of sick or dead rabbits to CDFW’s Wildlife Investigations Laboratory. To report sightings of sick or dead wild rabbits, hares or pikas contact the CDFW Wildlife Investigations Lab at (916) 358-2790 or file an online mortality report through CDFW’s website.

Outdoor recreationists should take precaution when hiking, camping or backpacking and not handle or disturb carcasses to minimize the potential spread of RHDV2. Additionally, hunters should take precautions to prevent spreading the virus, such as wearing gloves when field dressing rabbits, washing hands and burying remains onsite so that scavengers cannot spread the virus. The virus is hardy and can remain viable on meat, fur, clothing and equipment for a very long time, making it easily transmissible to other areas.

In California, hunting season for brush rabbits and cottontails opens July 1 and runs through the last Sunday in January. The season is open statewide, except for a closed area in the Central Valley near the riparian brush rabbit range. Hunting season for jackrabbits is year-round and statewide.

A vaccine for RHDV2 is not currently available in the U.S., thus domestic rabbit owners should practice good biosecurity measures to protect their animals from this disease, such as washing hands before and after working with rabbits, not sharing equipment with other owners and keeping their rabbits isolated from wild or feral rabbits.

Domestic rabbit owners who have a sick rabbit should contact their veterinarian. If domestic rabbits are found dead, please contact the local CDFA Animal Health Branch or call (916) 900-5002.

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Media Contacts:
Dr. Deana Clifford, CDFW Wildlife Investigations Laboratory, (916) 358-2378
Kirsten Macintyre, CDFW Communications, (916) 804-1714

Riparian brush rabbit photo courtesy of Moose Peterson. All rights reserved.

Survey Shows Severe Decline in Mount San Gorgonio Desert Bighorn Sheep Population

Aerial and ground surveys of Southern California’s Mount San Gorgonio desert bighorn sheep population conducted during early March have confirmed a severe decline in numbers. Biologists from the California Department of Fish and Wildlife (CDFW) and partner agencies counted 60 animals, approximately one-third the number counted in the last helicopter survey conducted in March 2016.

Watch video of biologists preparing for the survey at: https://youtu.be/ecdag5Y6d1g

This reduction appears to be consistent with an outbreak of respiratory disease that CDFW has been investigating since December.

“Die-offs of bighorn sheep of this type and magnitude that have occurred in the past have almost always been triggered by contact with domestic sheep or goats,” CDFW Wildlife Biologist Dr. Jeff Villepique said.

In December 2018, multiple reports of dead or dying bighorn sheep in Whitewater Canyon and the Mission Creek drainages were confirmed by biologists working for CDFW. Tissue samples from carcasses were sent to pathologists at the California Animal Health and Food Safety laboratories. The investigation is ongoing, with 21 bighorn carcasses identified thus far.

Administering medical treatment to sick bighorn is not feasible due to many factors, including the remote location, the difficulty of capturing animals and inability to capture and treat the entire herd.

Southern California is home to approximately 4,800 bighorn sheep in 64 herd units. To date, there have been no reports of sheep in nearby herds being affected by the disease.

CDFW is one of several entities involved in managing bighorn sheep in California, and participates in the Western Association of Fish and Wildlife Agencies Wild Sheep Working Group. The Group has declared respiratory disease to be “the biggest impediment to restoring and sustaining bighorn sheep populations.”

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Media Contacts:
Dr. Jeff Villepique, CDFW Inland Deserts Region, (909) 584-9012
Harry Morse, CDFW Communications, (208) 220-1169

 

Bighorn sheep ram

CDFW Investigating Die-Off of Desert Bighorn Sheep

Wildlife biologists from the California Department of Fish and Wildlife (CDFW) are investigating what appears to be a significant mortality event associated with respiratory disease among the San Gorgonio desert bighorn sheep population in Riverside County. CDFW has confirmed that at least 20 animals have died but suspects that total mortality may be greater.

“The significance of this outbreak to the San Gorgonio desert bighorn sheep population is being investigated,” explained Heidi Calvert, an environmental program manager with CDFW’s Inland Deserts Region. “Our top priority right now is to determine the source and nature of the disease so that we can identify the right management actions to mitigate future risk.”

CDFW staff began receiving reports of sick desert bighorn sheep in December 2018 and immediately began collecting samples for lab analysis. CDFW is continuing to survey and monitor the population to gather more information on the extent and magnitude of this loss to the population. Private landowners and partner agencies are assisting with this effort.

The Western Association of Fish and Wildlife Agencies Wild Sheep Working Group considers respiratory disease to be “the biggest impediment to restoring and sustaining bighorn sheep populations.” Respiratory disease in bighorn sheep is most commonly attributed to contact and/or proximity with domestic sheep and, to a lesser extent, domestic goats. Diseases that originate with domestic animals can pose a significant risk to bighorn sheep populations.

The affected desert bighorn population is located within Desert Bighorn Sheep Hunt Zone 5. The recent die-off will likely result in reducing the two hunting tags to zero in this zone for 2019.

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Media Contacts:
Heidi Calvert, CDFW Inland Deserts Region, (760) 872-0751 

Kirsten Macintyre, CDFW Communications, (916) 322-8988

Attorney General Becerra and the California Department of Fish and Wildlife Issue Legal Advisory on Migratory Bird Treaty Act

California Attorney General Xavier Becerra and the California Department of Fish and Wildlife (CDFW) today jointly released a legal advisory regarding the federal Migratory Bird Treaty Act (MBTA) and California’s protections for migratory birds. The advisory affirms that despite any reinterpretation of the MBTA by the federal government, California law continues to provide robust protections for birds, including the prohibition on incidental take of migratory birds.

The advisory – and a lawsuit filed by Attorney General Becerra as part of a multistate coalition in September 2018 – follows a decision by the federal government to roll back protections under the MBTA. The MBTA protects more than 1,000 native U.S. species of birds, including the bald eagle, America’s national bird, and other bird species that were near extinction before MBTA protections were put in place in 1918.

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Media Contacts:
Jordan Traverso, CDFW Communications, (916) 212-7352
Press Office for Attorney General Becerra, (916) 210-6000