Across the globe, scientists have shown that birds can be farmer allies. Insectivorous birds feed on damaging insect pests in many crops including coffee, cacao, oil palm, corn, cabbage and apples. Raptors, including hawks and barn owls, feed on rodents, including gophers, voles and mice (see blog, Barn owls help clean up rodents naturally).
Despite this deep historic knowledge that birds are important predators of crop pests, over time the perception of birds as natural enemies of pests has been generally replaced with the idea that birds are often major crop pests themselves. Indeed, some bird species — like some types of insects — can cause trouble for farmers, but many others — especially those that eat insects and rodents — can be beneficial.
Do birds control insect pests on farms in California's Central Valley?
They do! Recent studies by Dr. Sacha Heath, UC Davis, and Rachael Long, field crops and pest management advisor, UC Cooperative Extension, showed that birds help control insect pests in walnut orchards. Dr. Sara Kross (UC Davis postdoctoral alumnus, now with Columbia University) showed that birds help control alfalfa insect pests.
Birds are voracious predators of codling moth pests in walnuts
Codling moth is a major worm-like pest that infests walnuts, apples and pears. The larvae go dormant during winter, living in cocoons in crevices in trees. Adult moths emerge in the spring, lay eggs and infest crops.
We evaluated bird predation of codling moth using “sentinel prey” and exclosure cages. We glued codling moth cocoons to walnut trunks and covered them with cages, allowing insects and spiders to access the cocoons, but not bird predators. This allowed us to count how many larvae were eaten inside and outside of the cages to estimate pest reduction by birds.
What did we find?
Natural enemies, like parasitic wasps and lacewings, alone reduced codling moth larval numbers by 11%; adding birds into the pest control system reduced them by 46%! Nuttall's woodpeckers and white-breasted nuthatches did a lot of the work; these birds travel up and down the trunks of trees, searching for insects.
Above, a white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video by Sacha Heath.
Alfalfa weevils are no match for insectivorous birds
Alfalfa weevils are key pests of alfalfa, reducing yields and hay quality if left uncontrolled. Dr. Sara Kross looked at bird predation of this pest by excluding birds from alfalfa plants via cages, and counting the number of weevils inside and outside the cages. She found that birds reduced the number of weevils by more than 30%, showing their importance in helping to protect alfalfa from this serious pest.
Does field edge habitat, like hedgerows, help attract beneficial birds?
Yes! Hedgerows are important habitat for beneficial birds, serving as nesting, foraging and roosting sites. In a study in the Sacramento Valley, crop margins with hedgerows, tree lines and riparian buffers harbored up to six times more birds and up to three times more bird species than bare or weedy margins.
Walnut orchards adjacent to hedgerows and riparian areas had higher numbers of beneficial birds along with more species. In alfalfa, there were more beneficial birds in fields when at least two tall trees were present along the field edges. More beneficial birds were associated with better pest control, that is, fewer codling moth cocoons and alfalfa weevils.
Birds have large territories, fly long distances, and are influenced by what happens on the farm as well as by what happens in the landscape around the farm. For example, we found that codling moth predation by birds greatly increased in walnut orchards as the amount of habitat in the landscape around the orchards increased (including hedgerows, tree lines, riparian and oak woodlands, and grasslands).
Will hedgerows increase the numbers of pest birds?
Pest birds are present on farms regardless of field edge habitat (such as weedy vegetation or hedgerows). Cases will be different, depending on the crop, but in the fields and orchards of Yolo County, researcher Hillary White (formerly with UCCE and now with U.S. Fish and Wildlife) found that three of the most common avian crop pests (American crow, red-winged blackbird and Brewer's blackbird), were up to 10 times more abundant in agricultural fields with bare or weedy margins than in fields with hedgerows.
What can I do to attract beneficial birds to my farm?
Our avian research team has been quantifying the conditions under which birds are helpful or harmful to growers. We are looking for ways to help farmers create bird habitat on their farms to harness the beneficial pest control services birds can provide, while also protecting crops from the damaging effects of some bird species. This information is available in the new publication “Supporting Beneficial Birds and Managing Pest Birds,” co-authored by the Wild Farm Alliance and Drs. Kross and Heath, and technically advised by UC Cooperative Extension and several farmers. This is a user-friendly guide for farmers and conservation practitioners, with the goal of co-managing farmlands for biodiversity and farming.
A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)
Why are we in this situation? Multiple factors are involved. We suppressed wildfires in our forests for 100 years, and stopped using prescribed fire as a tool for ecosystem benefits and fuel reduction. Further, we have been experiencing hotter summers (so the window for burning is wider) and we've continued to build into wildfire-prone areas with home construction, lot layout and community planning that often are not up to the fire challenge.
Is there hope? I present these as my take always, noting there is more detail to be seen at the UC ANR fire and other websites (e.g., CFSC). I was impressed by the three relatively clear battle grounds we need to attend to:
- Our homes: how we build, layout and landscape our homes
- Our communities: how we structure our neighborhoods and communities
- Our forests and beyond: how we manage (what I'll call) the forests and wildlands. Each has particular needs and opportunities
While the above focuses on prevention and management of fires, the Summit had good representation of the health sector, reminding us of the need to help humans, domestic animals and wildlife affected and traumatized by fire events.
The Summit was deemed by the participants themselves as very successful. Kudos to the many organizations who participated. There is momentum building with a genuine desire to work together to help the people of California.
Want to learn more? Contact some of our experts, who served as the chairs of the Summit coordinating committee:
David Lile, Leader, Sustainable Natural Ecosystems Strategic Initiative, UC ANR
Lenya Quinn-Davidson, fire advisor, Cooperative Extension, Humboldt County, UC ANR
Yana Valachovic, forest advisor, Cooperative Extension, Humboldt and Del Norte County, UC ANR
Want more? See UC ANR fire
While scientific reports continue to mount confirming that global climate change is increasing temperatures, causing more frequent weather extremes and raising the sea level in California, UC Cooperative Extension is working to ensure the worst predictions are avoided and California residents and businesses will be able to adapt to the change.
Each year, a diverse group of UC Agriculture and Natural Resources academics and program implementation professionals meet to share and collect the latest climate change experiences, ideas, science and solutions. The team works with farmers across the state to improve production practices and minimize environmental impact, conduct agricultural and natural resources conservation research, and coordinate programs like California Naturalist and UC Master Gardener, which recruit and educate volunteers to reach out to communities statewide to extend research-based information.
Reaching real people
In 2019, extension practitioners explored new approaches to delivery of information and services. For example, the first speaker addressed the way climate change impacts may be viewed through the lens of African-American or First Nation experiences, influenced by poverty, historical trauma and even spirituality.
Theopia Jackson, clinical psychologist at Saybrook University in Oakland, encouraged the team to consider whether assisting Americans navigating the changing climate or suffering the consequences of extreme weather events have “the bandwidth to take in one more helping hand.” Jackson has a long history of providing therapy services, specializing in serving populations coping with chronic illness and complex trauma.
Jackson suggested helpers ask themselves, “Are we inadvertently causing more stress than good? Do I have a sense for what they are already dealing with before bringing something new into the community?”
Jackson said the conversation about climate change in many communities might be more productive focused less on whether climate change exists or not, and instead on how to “join with them around the human experience.”
“If I'm trying to ‘talk them into it,' I need to step back,” Jackson said. “The conversation could be about scarcity or lifestyle. We need to find a way to join and hope they will get it before we've done irreversible damage.”
The careful selection of terminology and approach in climate change conversations was also raised by Dan Sonke, director of sustainable agriculture for Campbell's Soup. The company's primary and best-known product is soup, but it owns other familiar brands, including Pepperidge Farms, Snyder Pretzels, Kettle Chips and Emerald Nuts.
In California, Sonke works closely with farmers producing fresh produce to be used in Campbell's products, particularly processing tomatoes. During his career, he also worked in Campbell's marketing, based on its “corporate purpose.”
“We make real food for real people,” says the Campbell's corporate purpose. “People love that our food fits their real lives, fuels their bodies, and feeds their souls. And they appreciate knowing what goes into our food, and why — so they can feel good about the choices they make, for themselves and their loved ones.”
Sonke was hired to increase the use of sustainable farming practices by the company's producers and help farmers apply for grant funding from the state to implement climate-smart irrigation practices. The company was able to track a 20 percent reduction in water use and document a significant reduction in the emission of nitrous oxide, a greenhouse gas. The program is successful, but isn't driving their farmer communications or soup sales, Sonke said.
“Farmers don't think in terms of climate change, but they respond to what they know,” Sonke said. “Consumers don't respond to climate change adaptation in terms of what products they buy. They respect sustainability, but have no understanding of ‘sustainable agriculture' and ‘carbon sequestration.'”
Growing UCCE climate mitigation, adaptation and resilience programs
UC ANR is working on new ways to reach out to farmers and the public with information on climate change. Six community education specialists have been hired and four more are being recruited to work in counties around the state to help farmers access programs that will help them reduce greenhouse gas emissions on farms and dairies, build resilience to climate change and increase profit.
The Climate-Smart Farming Program is a collaborative effort with the California Department of Food and Agriculture focused on implementing on-farm solutions to improve soil health, nutrient management, irrigation management, on-farm composting and manure management.
The CDFA programs involved are:
- State Water Efficiency and Enhancement Program
- Healthy Soils Program
- Alternative Manure Management Program
The new community education specialists are already deployed in Mendocino, Glenn, Yolo, Santa Cruz, Ventura and San Diego counties. The four positions under recruitment will serve Imperial, San Joaquin, Fresno and Kern counties. To get information about these programs, contact:
- Fresno County, UCCE advisor Dan Munk, firstname.lastname@example.org
- Glenn County, UCCE advisor Betsy Karle, email@example.com
- Imperial County, UCCE advisor Oli Bachie, firstname.lastname@example.org
- Kern County, UCCE advisor Brian Marsh, email@example.com
- Mendocino County, UCCE advisor Glenn McGourty, firstname.lastname@example.org
- San Diego County, UCCE advisor Laurent Ahiablame, email@example.com
- San Joaquin County, UCCE advisor Brent Holtz, firstname.lastname@example.org
- Santa Cruz County, UCCE advisor Mark Bolda, email@example.com
- Ventura County, UCCE advisor Ben Faber, firstname.lastname@example.org
- Yolo County, UCCE advisor Morgan Doran, email@example.com
To reach a broad swath of California residents with research-based information on climate change mitigation and adaptation, UC ANR's California Naturalist program is leveraging its well-established partnerships with formal and informal science education institutions across the state to create a legion of climate stewards. At the team meeting, CalNat coordinator Greg Ira announced that the California Naturalist program has hired an academic coordinator to develop curriculum that will allow existing partners to deliver the material as part of the California Naturalist program. The graduates of this California Naturalist course focused on climate change will be encouraged to engage in volunteer service that helps build community resilience to climate change. These include participation in local adaptation planning efforts, community and citizen science projects, or addressing issues of social justice. The coordinator begins Feb. 19.
Renata Brillinger of the California Climate Action Network shared optimistic thoughts about the opportunities for climate change mitigation, adaptation and resilience. In terms of politics, she said California leadership has accepted climate change as a settled matter and are supportive of programs to address the issue. At the federal level, it is not easy to talk about climate change, but “that will change,” she assured.
Brillinger said biodiversification of California is an exciting area for climate change adaptation. Research is needed to understand how to shift crop locations for future production, and determine where, for example, water-intensive crops or orchards with chill requirements should be grown. More information is needed, she said, on how healthy soil will relate to climate resilience in agriculture.
“We have to reinvest in extension and Resource Conservation Districts,” Brillinger said.
Other possible climate change outcomes in California may be returning farmland to less-intensive uses, such as grazing. Fallowing land was one way that the agriculture industry coped with the drought of 2011-16, and implementation of the Sustainable Groundwater Management Act – a direct result of the drought – is estimated to take 1 million acres of farmland out of production. This approach won't be a solution for all farmers and ranchers, said David Lile, UC Cooperative Extension natural resources advisor.
“Ranchers and farmers interested in long-term sustainability, keeping the farm in place, will need help to integrate competing forces,” Lile said. “Economics will not be the only driving force.”
Help the environment on Earth Day, which falls on April 22, by growing insectary plants. These plants attract natural enemies such as lady beetles, lacewings, and parasitic wasps. Natural enemies provide biological pest control and can reduce the need for insecticides. Visit the new UC IPM Insectary Plants webpage to learn how to use these plants to your advantage.
The buzz about insectary plants
Biological control, or the use of natural enemies to reduce pests, is an important component of integrated pest management. Fields and orchards may miss out on this control if they do not offer sufficient habitat for natural enemies to thrive. Insectary plants (or insectaries) can change that — they feed and shelter these important insects and make the environment more favorable to them. For instance, sweet alyssum planted near lettuce fields encourages syrphid flies to lay their eggs on crops. More syrphid eggs means more syrphid larvae eating aphids, and perhaps a reduced need for insecticides. Similarly, planting cover crops like buckwheat within vineyards can attract predatory insects, spiders, and parasitic wasps, ultimately keeping leafhoppers and thrips under control.
Flowering insectaries also provide food for bees and other pollinators. There are both greater numbers and more kinds of native bees in fields with an insectary consisting of a row of native shrubs planted along the field edge (called a hedgerow). Native bees also stay in fields with these shrubs longer than they do in fields without them. Therefore, not only do insectaries attract natural enemies, but they can also boost crop pollination and help keep bees healthy.
Insectary plants may attract more pests to your plants, but the benefit is greater than the risk
The possibility of creating more pest problems has been a concern when it comes to installing insectaries. Current research shows that mature hedgerows, in particular, bring more benefits than risks. Hedgerows attract far more natural enemies than insect pests. And despite the fact that birds, rabbits, and mice find refuge in hedgerows, the presence of hedgerows neither increases animal pest problems in the field, nor crop contamination by animal-vectored pathogens. Hedgerow insectaries both benefit wildlife and help to control pests.
How can I install insectary plants?
Visit the Insectary Plants webpage to learn how to establish and manage insectary plants, and determine which types of insectaries may suit your needs and situation. If you need financial assistance to establish insectaries on your farm, consider applying for Conservation Action Plan funds from the Environmental Quality Incentives Program (EQIP) offered by the Natural Resources Conservation Service.
- Flower flies (Syrphidae) and other biological control agents for aphids in vegetable crops. (PDF)
- Good news for hedgerows: no effects on food safety in the field.
- Hedgerow benefits align with food production and sustainability goals.
- Habitat restoration promotes pollinator persistence and colonization in intensively managed agriculture. (PDF)
- Reducing the abundance of leafhoppers and thrips in a northern California organic vineyard through maintenance of full season floral diversity with summer cover crops.
Have you ever been on a walk and observed an interesting plant you couldn't identify? Encountered an unusual insect trapped in your home? Have you wondered why you used to see certain species in nature and you don't now? Or have you thought it might be neat to compile a species list for a special place, like a favorite park or your own backyard? All California Naturalists already know that there's an app (and website) for all that!
What is iNaturalist?
The free iNaturalist app is an online social network of people sharing biodiversity information to help each other learn about nature. Available for android, iPhone, and by a website, iNaturalist is a joint initiative by the California Academy of Sciences and the National Geographic Society that allows users to upload one or more pictures, provide a location, and make relevant notes like whether the subject is captivate or wild.
In response, the artificial intelligence in the app suggests what the species might be based on visual similarity and whether the species has been observed nearby. Members and organizations can set up projects and download data within defined taxa or locations to follow presence and absence, abundance, seasonality and change over time.
Verified observations are sent to the Global Biodiversity Information Facility, an international network and research infrastructure funded by the world's governments and aimed at providing anyone, anywhere, open access to data about all types of life on earth. Valuable open-source data is available to aid scientific research, government and conservation organizations, and the interested public. Nearly instant gratification for species ID combined with the ability of members to contribute to a greater good whenever they venture outdoors are huge motivators for much of the existing iNaturalist community, which currently exceeds one million users and 14 million observations.
iNaturalist observations and the upcoming City Nature Challenge
One of the biggest BioBlitzes naturalists and others can participate in is the annual City Nature Challenge. The City Nature Challenge — essentially a four-day global urban bioblitz — began in 2016 as a friendly nature-observation competition between the San Francisco Bay Area and Los Angeles County, organized around a simple charge: “which city can find the most nature?” Participants use the iNaturalist app to photograph, catalog, identify and organize observations of wildlife in their areas. The city with the highest number of observations wins. Since the first challenge, the competition has expanded rapidly, and this year more than 150 cities will participate worldwide.
How does it work?
The City Nature Challenge takes place April 26-29, 2019. During this window, anyone can contribute observations via iNaturalist. There will are also be a variety of events organized to help cities win the challenge. Cities are competing against each other to see which city can make the most observations of nature, find the most species, and engage the most people. At the end of the observation window on April 29, other events will be held to help participants identify and complete their observations in iNaturalist.
How can we participate in 2019?
The UC Agriculture and Natural Resources' California Naturalist program is teaming up with the UC Davis School of Education's Center for Community and Citizen Science, UC Davis Evolution and Ecology Department, and other partners in the region to put the Sacramento region in the competition for the first time. Stay updated and learn more information about how to join the fun on the Sacramento City Nature Challenge website as we add events. Experienced and beginner naturalists alike are invited to attend these events.
For those outside of the Sacramento region, participate in the Natural History Museum of LA County's Los Angeles County City Nature Challenge, San Diego Natural History Museum's San Diego County City Nature Challenge, and the California Academy of Sciences' San Francisco Bay Area City Nature Challenge. All you have to do is log in to your account and join the project. Any observations uploaded from within the project boundaries from April 26-29 are automatically contributed to the challenge.
Last year, 6 percent of the nearly 7 billion total observations uploaded to iNaturalist were contributed during the City Nature Challenge, making the challenge the single-most uploaded period of 2018. With the City Nature Challenge growing internationally in 2019, even more observations will be added in the hopes of getting more people outside, engaging with the natural spaces within urban environments, spending time with fellow nature enthusiasts and community organizations, and learning and contributing to science.