Wildfires, smoke and livestock: What can we do?

Wildfire trends in North America

The risk that wildfires pose to people and the environment is increasing because of numerous factors including, but not limited to, climate change. Other factors, such as the spread of invasive annual species, drive larger, more frequent wildfires in western regions. Additionally, increasing recreation on public lands and changes in where people choose to live have exacerbated the risks that wildfires pose. For instance, more people living in the wildland-urban interface means a greater risk of ignition and greater losses from wildfire events.

A 2021 report from the Intergovernmental Panel on Climate Change indicates that weather conducive to wildfires (hot, dry and windy) has become more frequent in the West and will continue to increase with greater levels of global warming. While we cannot eliminate the risk of wildfires, we can act strategically to manage and reduce risks, such as by creating and executing a fuels management plan, creating defensible space and establishing fire breaks.

Wildfire hazards: fire

Losses from wildfire are largely self-evident. In the most tragic circumstances, there is loss of human life. In agricultural communities, we are also concerned about death and severe injury to livestock that can result from flames, intense smoke inhalation or animals stampeding out of panic. Fire can also destroy infrastructure such as barns, corrals and fences, and feed, including stored hay and forage on the landscape.

Wildfire hazards: smoke

As wildfires increase in frequency, size and duration, more humans and animals are exposed to wildfire smoke. Smoke can disperse great distances and increase disease susceptibility and death in populations removed from the wildfire origin.

Smoke from wildfires is chemically complex, comprising a range of potentially toxic combustion products and fine particulate matter. The composition of smoke depends on factors such as fire behavior, vegetation type, season, burn conditions and available fuel. Particulate matter smaller than 2.5 μm (PM_2.5) is the major smoke component of concern, as PM_2.5 can be inhaled deeply into the lungs. Wildfire smoke also contains other hazardous compounds such as carbon monoxide, nitrogen dioxide, nitrous oxide, polycyclic aromatic hydrocarbons, ozone, sulfur dioxide and hydrogen cyanide.

How to reduce fire risk on the landscape

What drives fire? What can we control?

During fire season, it is important to be aware of day-to-day weather conditions and local landscape features and how they may influence fire occurrence and potential fire behavior. Long-term drought, higher than normal maximum temperatures coupled with very low humidity and low fuel moisture are weather characteristics that increase fire hazards. However, we have limited control over weather and topography. We can control the amount, type and distribution of fuel on our properties.

Fuel characteristics determine how likely a fire will start, how quickly it will spread, how easily it can be controlled and the severity and ecological consequences of that fire. On rangelands, fine fuels, such as perennial and annual grasses, do not burn for long but effectively carry fire across a landscape. Woody fuels (shrubs and trees) tend to burn longer and hotter, affecting fire spread and burn severity. Highly volatile fuels such as sagebrush and western juniper produce more extreme fire behavior, including greater fire intensity, longer flame lengths and more rapid rates of spread.

Fuel arrangement refers to how fuels are distributed, which influences how quickly fire will spread. If fuels are densely arranged and highly continuous, they easily transmit fire to surrounding vegetation. Because perennial bunchgrasses create large interspaces between plants, potential rate of fire spread at a site dominated by bunchgrasses is comparatively lower than at a site with invasive annual grasses such as medusahead and cheatgrass. Invasive annual grasses grow close together and accumulate as litter over multiple growing seasons, creating a highly flammable, continuous layer of fine fuel.

Strategic fuels management

Strategic fuels management — changing the type and amount of fuel and its distribution — can influence the likelihood of wildfire and how fire is expected to behave. Managing hazardous and fine fuels, promoting plant community resilience and creating strategic fuel breaks are long-term strategies that land managers can use to reduce risk for wildfire ignition and spread on their properties.

Manage hazardous and fine fuels

Hazardous fuels burn intensely, produce large flame lengths and increase the risk of spotting and rapid fire spread during fire events. Western juniper and sagebrush account for most of the hazardous fuels on rangelands. Removing, thinning or rearranging these fuels should be prioritized around homes, ranch infrastructure and roads or trails that are important for evacuation or fire response operations. For brush, mowing, crushing and dragging techniques can reduce plant density and cover, with varying degrees of mortality and surface disturbance.

Manual cutting of juniper is effective and produces relatively little ground disturbance, though this technique rearranges rather than removes fuels; land managers might consider burning or scattering juniper slash. Prescribed fire is effective for treating juniper and reducing the seedbank. Before treating, consider the need for post-treatment weed control or seeding. A maintenance cut a few years after an initial juniper treatment will extend the project’s lifespan. This can also be informed by site conditions, understory species before the treatment and the potential for invasion by annual grasses. For example, if an understory lacks perennial bunchgrasses and there’s a risk of invasive grasses colonizing following surface disturbance, it may be appropriate to seed concurrently with a mechanical treatment.

To manage fine fuel loads on a landscape, proper livestock grazing is an important tool. Moderate grazing, with 40% to 50% of forage utilization, during the growing season removes biomass, effectively disrupting fuel continuity and reducing overall fuel loads. A study at the Eastern Oregon Agricultural Research Center found perennial bunchgrasses were 200% more likely to burn if not grazed than plots grazed by cattle in the spring. Furthermore, fall and winter grazing can remove the highly flammable litter that tends to build up in the centers of bunchgrasses over multiple growing seasons. Removing this litter means the overall moisture content of grazed plants is higher than ungrazed ones; these plants are less receptive to ignition later into the fire season.

Promote plant community resilience to wildfire

Treating invasive annual grasses (IAG) and promoting perennial bunchgrasses reduce fuel continuity (and, thereby, potential for rapid fire spread) and increases plant population that will retain moisture longer into the fire season, making them less receptive to ignition.

In the short term, focus on treating invasive annual grasses and reducing opportunities for seeds to disperse. Land managers might apply selective herbicides (For example, a pre-emergent herbicide in fall) to control IAGs and minimize damage to desirable perennial species. For some locations, such as federal lands, you might need approval to use herbicides. Competitive species may be seeded around smaller infestations; crested wheatgrass often competes well with cheatgrass and can exclude it.

To reduce seed dispersal, limit vehicle, animal and human contact with seeds. When contact does occur, spray seeds off vehicles and brush them off boots and clothing. If possible, do not move livestock directly from infested fields to uninvaded areas. Although the retention time of potential weed seeds in the gastrointestinal tract of livestock is heavily dependent on the digestibility of the diet, a 30-70 hours quarantine should help reduce the gastrointestinal load.

Roads are common pathways for seed dispersal; treat roadsides to create IAG-free corridors. Over time, monitor and detect new infestations by surveying along roads, animal trails and random locations. Disturbed areas (For example, where heavy equipment has been used or areas that recently burned) may be particularly susceptible to invasion.

In the longer term, increasing plant community resistance to invasion and resilience to fire is essential. Perennial bunchgrasses create large interspaces and remain green later in the fire season than invasive annual grasses. This lower fuel continuity and higher fuel moisture mean fire is less likely to ignite and spread. Some sites are generally more resistant to invasive annual grasses — the existing plant community can outcompete them. Sites with high perennial bunchgrass abundance and wetter, cooler sites (For example, higher elevation and north-facing slopes) are generally more resistant to invasion. Following disturbances such as fire, focus on activities that will promote the growth of these resistant and resilient plant communities around these areas.

Create strategic fuel breaks or lighter fuel areas

Fuel breaks modify fuels in strategic locations and function to:

• Reduce the chance of a fire starting off roads or other heavily traveled areas.
• Reduce and moderate fire behavior (for example, slow the rate of spread).
• Offer wildland fire responders a safe tactical space.

Fuel breaks may be maintained on roads, two tracks, mowed or annually disked areas, or vegetative green strips. During wildfire events, flame lengths are influenced in part by the type of vegetation that is burning. The width of a fuel break should reflect the fuel type and expected flame lengths. For instance, flame lengths may be 4 to 6 feet high in cheatgrass, while sagebrush may produce 12- to 18-foot flames. As a result, a fuel break in a site dominated by sagebrush should be considerably wider than one with primarily cheatgrass. As a general rule of thumb, a fuel break on flat terrain should be two to three times the height of the tallest vegetation, though it is best to consult with a fuels specialist with knowledge of local wildland fire behavior.

Fuel breaks can be created in strategic places by:

• Disrupting fuel continuity or reducing fuel loads: Graze, mow, disc, spray— any activity that removes or rearranges fuels (creating separation between plants or reducing their height or volume).
• Removing hazardous fuels: Cut juniper, mow brush — target highly volatile fuels to reduce flame length and rate of spread in the event of a fire.
• Seeding fire-resistant species: Select ones that readily establish, are difficult to ignite (that is, they stay greener later into fire season) and ideally offer livestock forage. Options include forage Kochia, Crested or Siberian wheatgrass, Sandberg bluegrass.

Treatments along ranch roads or long driveways may be a priority; many human-caused ignitions occur near roads. Planting light or unreceptive fuels in these areas reduces the likelihood that a spark will propagate a fire.

How to reduce fire risk around barns and other infrastructure

Thinking about potential ignitions, how fuels are distributed and how fire will behave is a first step in identifying a farm or ranch’s priorities — before fire season. How do fuels need to be modified to protect the ranch’s assets?

• Maintain defensible space around homes, barns, outbuildings, wells or pumps and other infrastructure. Wildfires often cast embers ahead of a flaming front. To reduce the potential for ignition, create a buffer of noncombustible materials in the 5 feet immediately around structures. The space 30–100 feet beyond should be relatively devoid of highly combustible fuels. Feed, packing boxes, mulch and fuel supplies are particularly susceptible.
• Clear vegetation around equipment, fuel tanks and forage and haystacks.
• Improve or maintain safe access routes for fire responders or for evacuation.

Consider these activities before each fire season. They may require ongoing effort.

How to plan for when fire threatens your farm or ranch

What will you do if a wildfire threatens your ranch or farm? The most important thing to do is to create a fire response plan. Create your plan in electronic form for easy sharing as well as in an easily accessible hard copy. When developing the response plan, seek input from all family members and employees who may play a role in executing the plan. Below are some considerations for livestock producers when preparing for an emergency such as wildfires. such as wildfires.

Additionally, OSU Extension has developed a form you can follow when developing your plan, Emergency Action Plan for Medical and Fire Emergencies.

Communicating with family, workers, friends, colleagues, neighbors

• Who will be responsible for what tasks? Include a backup person when possible.
• What are the locations of important infrastructure, resources and access routes? Include a labeled map or satellite image that can be shared.
• Where will neighbors’ livestock be?
• Get to know local fire responders.
• If livestock uses grazing allotments, will you receive notifications about wildfires?
• What locations might house evacuated livestock? Options could include property of friends, relatives or colleagues; fairgrounds, racetracks, show grounds, stables, equestrian centers, stockyards, auction barns and public and federal lands.

Supporting effective fire response

• Where are water resources? Clearly mark water tanks, ponds and other water supplies for fire responders. If pumping water will be necessary, is there a backup system in case of power loss?
• Where are the best access routes for fire response resources?
• A hard, durable road surface is useful within 10 feet of water sources for water tenders and large engines. Keep these locations clear of vegetation and debris for ready access. Mark turnarounds near or at water sources.
• Post bridge load limits and bridge heights for fire suppression resources.
• Provide fire responders with a list of important phone numbers, a map with livestock locations, gate codes, fuel breaks or areas of light fuels, access roads and any hazards on the ranch or farm.

Protecting livestock

• Which animals will be evacuated? Which animals will shelter in place?
• If livestock will be evacuated, where will they go? Have two or three options in your plan.
• Are livestock in multiple locations? Are there any access issues, such as narrow roads that are difficult for stock trailers? Consider the access needed by inbound fire response resources.
• If evacuation is necessary, where are loading and unloading facilities? Who will gather livestock? Do they know how to get them to their destination?
• Are there pastures for livestock to shelter in place?
• Will livestock have water if the power goes out?
• Are livestock branded and tagged?
  

What to do during fire season

Stay informed

Whether you own livestock or not, it is extremely important to stay informed during wildfire season. Always check city and county emergency service websites and social media. Check local news, TV and radio for updates, and opt in to emergency alerts from your county. Additionally, enable Wireless Emergency Alerts (WEA) on your cell phone and keep it charged to receive notifications. Cellphone applications such as Watch Duty are also reliable sources of up-to-date information. Stay informed about the progress of wildfires and follow official recommendations, especially evacuation orders.

Update your fire response plan as needed

Be sure to provide fire responders with updated information. Include the date in your records.
How to evacuate livestock

• Decide which animals will be evacuated and which will shelter in place.
• Confirm that your intended evacuation site(s) can take them.
• Arrange the transportation.
• Move animals calmly and slowly; use low-stress handling techniques.
• Evacuate as early as possible.
• Whenever possible, move animals in daylight. There is less chance for mistakes or accidents and less stress for animals when they arrive at the evacuation site.
• Keep a record of which animals are going where. Take photos of trailer loads as they leave. This is especially important if you are getting help from volunteers or people you do not know well.
• Keep animal records up-to-date and available; it might be necessary to show herd health records to places that might take your animals during evacuation.

Returning

Before moving livestock back, make sure that feed and water sources are safe for consumption and are in a location easily accessible and familiar to the animals. Repair essential fences and other structures. Only return animals to your operation when authorities allow you to do so. If returning animals to their origin is not possible, develop a longer-term plan for them.

How to provide for livestock that will shelter in place

Sometimes, livestock will have to remain at the property. In these cases, move animals to the safest location possible.

• Ideally, have animals in a pasture light on fuel — for example, a pasture that has been heavily grazed.
• If irrigation is available, leave it on to protect animals.
• Leave gates open so animals can move freely and easily.
• Provide animals with water and feed in a safe location, estimating enough supplies for seven to 10 days.
• Shut off electricity, propane and other fuels. If possible, leave water running.
• When possible, store dry, highly flammable feed and bedding materials in structures separate from animal housing.

In the case of commercial dairy farms, where transportation and a lack of available milking facilities can pose problems, the best option may be to shelter in place with the knowledge and advice of fire and emergency response professionals. Take care to minimize the chance that a wind-blown spark can ignite a structure or nearby vegetation. Consider constructing firebreaks, such as a strip of disked, plowed or scraped ground, around barns without gravel, bare earth or green vegetation. Set up sprinklers to keep any flammable components of the barn and the area surrounding it damp. Remove or wet any dry bedding inside a barn with animals. If cows are often housed on irrigated pasture, consider keeping them there rather than in the barn. If possible, evacuate animals that can be moved easily, such as calves, heifers and dry cows.

Returning

When authorities allow you to return to your property, ensure that water and feed sources are safe for consumption. Repair fences and other structures that might pose a hazard. Locate your livestock and report any missing animals to local authorities or your neighbors. Upon gathering animals, assess their condition. If needed, contact your veterinarian to develop an animal health recovery plan.

Animal recovery plan

Work with your veterinarian to help you triage injured animals and develop an animal treatment plan. Examine animals carefully. The depth and severity of burns may be difficult to evaluate, especially if the animal does not appear in pain. Burns can destroy nerve endings, meaning the animal may not show signs of pain despite severe tissue damage. In fact, burn injuries are considered the most traumatic type of wound. Severely burned animals experiencing skin damage and shock may need to be euthanized.

Once you’ve set up treatment plans, separate animals by the level of treatment needed. This will allow better care of those animals and help you gauge animal recovery. Check animals’ progress daily and keep track of feeding habits —going off-feed is an indicator of illness.

In cases of livestock mortality, follow best practices for disposing of carcasses. Often, burial, composting, disposal at a landfill and incineration are acceptable practices, but regulations can differ among states and counties. Check with the Department of Agriculture before disposing of carcasses.

How to minimize the effects of smoke on livestock

Stay informed

Air quality reports use the Air Quality Index (AQI). The U.S. Environmental Protection Agency establishes an AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, PM2.5 and PM10, carbon monoxide, sulfur dioxide and nitrogen dioxide. Each has a national air quality standard set by EPA to protect public health. The AQI is color-coded; as air quality decreases, the AQI value increases (Figure 1). The higher the AQI value — particularly the contribution of PM2.5 from wildfire smoke — the greater the level of air pollution and the greater the health concern.

Air Quality Index values are readily accessible from EPA via the AirNow website. You can enter a location and obtain current AQI readings from the closest monitoring station, along with a note about the primary pollutant (of the five listed above) at that moment. You can also also access archived data if you want to know about air quality in the past. AirNow is also available as an app for mobile devices.

Observe livestock

Signs of possible smoke or dust irritation in animals include but are not limited to coughing or gagging; difficulty breathing, including open-mouth breathing and increased noise when breathing; eye irritation and excessive watering; inflammation of throat or mouth tissues; nasal discharge; asthma-like symptoms; increased breathing rate; fatigue or weakness; disorientation or stumbling; reduced appetite; or thirst. However, note that animals may show none of these signs and still be experiencing stress from smoke.

Actions to take

• Reduce activity and exercise while still allowing for normal behavior.
• Postpone stressful events like weaning, changing groups, vaccinations and transporting, if possible, until air quality improves.
• Keep clean, fresh water available at all times. (Well-hydrated respiratory tracts get less irritated.)
• Provide cooling such as shade, fans or misters. Heat stress has been shown to compound negative outcomes associated with wildfire smoke exposure in cattle.
• Reduce dust from feed or facilities by misting or sprinkling with water.
• Minimize other stressors!

Research is underway to identify other means of reducing the impact of wildfire smoke on livestock. There may be nutritional supplements or other treatments that may effectively mitigate the physiological burden of poor air quality, but they have not yet been determined. Stay informed about the latest discoveries in this area by visiting the Livestock and Wildfire Research Group’s Livestock Wildfire Hub.

IPCC. 2021. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

O’Hara, K. C., J. Ranches, L. M. Roche, T. K. Schohr, R. C. Busch and G. U. Maier. 2021. Impacts from Wildfires on Livestock Health and Production: Producer Perspectives. Animals. 11:3230. doi:10.3390/ani11113230. Available from: https://doi.org/10.3390/ ani11113230%0AAcademic

This project is supported by Agriculture and Food Research Initiative Competitive Grant No. 2023-68008-39173 and Grant No. 2022-68016-38665 from the USDA National Institute of Food and Agriculture. The findings and conclusions in this preliminary publication have not been formally disseminated by the U S. Department of Agriculture and should not be construed to represent any agency determination or policy.