California Olive Farmers Turn to Birds for Natural Pest Control

Since the launch of California’s sus­tain­able pest man­age­ment roadmap in January, farm­ers and offi­cials across the Golden State have been work­ing to con­trol pests with­out harm­ful chem­i­cal inter­ven­tions.

Farmers are doing this in the state’s olive groves by cre­at­ing diverse habits to appeal to ben­e­fi­cial bird species.

“Studies show birds are for­ag­ing on a vari­ety of crops, includ­ing olives,” Jo Ann Baumgartner, the exec­u­tive direc­tor of the Wild Farm Alliance, told Olive Oil Times. ​“The most impact­ful thing a farmer can do to increase avian pest con­trol is to add diverse habi­tat to the farm.”

“This can be in the form of native plant species as well as nest boxes to diver­sify the bird com­mu­nity,” she added. ​“The more bird species present, the more pest con­trol.”

Liz Tagami, the gen­eral man­ager of Lucero Olive Oil, told Olive Oil Times that encour­ag­ing bird-friendly habi­tats helps to fos­ter a holis­tic ecosys­tem and pro­vides a range of ben­e­fits to olive farm­ers.

“We gain nat­ural pest con­trollers with insec­ti­vores such as chick­adees in the spring or goldfinches and jun­cos in the fall,” she said. ​“These lit­tle birds act as mobile fer­til­iz­ers because their drop­pings con­tribute nitro­gen and phos­pho­rus, enhanc­ing soil health with­out petro­chem­i­cal inputs.”

Located in Corning, California, Tagami said native trees, includ­ing mature val­ley oak, divide the main blocks of olive groves and pro­vide habi­tats for larger birds of prey, which help main­tain a bal­anced ecosys­tem.

“We rou­tinely see Cooper’s and red-tailed hawks along with kestrels hunt­ing for ground squir­rels and other rodents dur­ing the day – lit­tle pests that can wreak havoc with irri­ga­tion sys­tems and tree roots,” Tagami said.

Since 2000, the Wild Farm Alliance has worked with farm­ers to achieve healthy, viable agri­cul­ture that pro­tects and restores wild nature. The alliance rec­om­mends var­i­ous strate­gies for farm­ers who want to encour­age birds as pest con­trol allies, includ­ing adding perches and nest sites.

“Whether arti­fi­cial poles, snags, peren­nial trees and shrub or annual tall plants, these can all serve as hunt­ing perches for large rap­tors and small birds,” Baumgartner said. ​“Placing nest boxes and nest shelves and allow­ing birds to nest in barns under eaves or on the ground pro­vide them with the nest­ing sites they seek for rais­ing their young.”

Birds help reduce olive fruit flies in two stages: lar­vae in the fruit and pupae on the ground. ​“Studies show that olive fruit eaten by birds mostly con­tained lar­vae, sug­gest­ing that birds do not hurt pro­duc­tion,” Baumgartner said.

“Birds con­sumed 65 to 71 per­cent of the pupae in the soil, and ants attacked most of the rest,” she added. ​“Further, birds were one of sev­eral impor­tant preda­tors of olive fruit fly pupae along with ants, bee­tles and cen­tipedes.”

Olive pro­duc­ers can cre­ate bird-friendly habi­tats as part of a holis­tic approach to inte­grated pest man­age­ment. ​“Setting aside extra acreage along perime­ters for native plants that sup­port birds and insects is a key com­po­nent in a com­plete sys­tem,” Tagami said.

Native hedgerows are increas­ingly pop­u­lar. ​“This can be accom­plished with a ​‘pol­li­na­tor hedgerow’ of densely planted native peren­nial grasses, shrubs and small trees – not ole­an­der, despite its ubiq­uity in California,” Tagami said. ​“Oleander is a non-native and inva­sive species, which is toxic to birds and ani­mals.”

“In addi­tion to a native pol­li­na­tor hedgerow, areas with­out mature trees adja­cent to the prop­erty are well served to install owl boxes; we’ll be employ­ing both strate­gies in a smaller orchard being planted next spring,” she added.

Baumgartner under­lined four best prac­tices to sup­port ben­e­fi­cial birds on California olive farms: care­ful prun­ing and har­vest­ing, adding native habi­tat, remov­ing inva­sive species and pro­vid­ing water.

“Native bird species have evolved to uti­lize native plants. Birds have adapted their migra­tion pat­terns, breed­ing sea­sons, behav­ior and mor­phol­ogy to suit best the land­scape in which they evolved,” Baumgartner said. ​“A good way to limit inva­sive species while also help­ing native bird pop­u­la­tions is to mon­i­tor for intro­duc­tions reg­u­larly and imme­di­ately man­age them before they spread.”

In terms of pro­vid­ing water, birds and wildlife need water year-round to sur­vive. Various water sources attract a diver­sity of birds, giv­ing them some­where to drink, feed and breed.

“People tend to think of birds as either pests or as ben­e­fi­cial, but often­times it’s not so straight­for­ward,” Baumgartner said. ​“The sea­son, a bird’s life cycle and avail­able food sources will dic­tate whether a bird will pro­vide pest con­trol ser­vices or will dam­age a crop.”

“Most song­birds are ben­e­fi­cial dur­ing the nest­ing sea­son as they feed pest insects to their rav­en­ous nestlings, and many of these song­birds will con­tinue to eat insects through­out the year,” she added.

“Most omni­vores, how­ever, will switch to a plant-based diet in the fall. The omni­vores that con­gre­gate in large flocks (think black­birds and star­lings) will become a nui­sance as they eat fruit or nuts before har­vest,” Baumgartner con­tin­ued.

“If the win­dow for dam­age can be man­aged, the over­all ben­e­fit to the crop can be main­tained,” she said. ​“Another aspect to keep in mind is that birds not only eat insects directly, but they also clean up mummy fruit and nuts that would har­bor over­win­ter­ing pest insects and dis­eases. This will save farm­ers on removal of mum­mi­fied fruits and nuts post-har­vest.”

Integrated pest man­age­ment is part of a larger pic­ture of regen­er­a­tive and resilient agri­cul­ture prac­tices.

“Folks who are not part of daily oper­a­tions tend to for­get that IPM and regen­er­a­tive prac­tices are dynamic,” Tagami said. ​“Each prop­erty is unique, and strate­gies must be deployed, mon­i­tored and adjusted to ensure goals are met.”

“Biodiversity loss due to habi­tat loss – whether through com­mer­cial devel­op­ment, the spread of non-native plant species or the fast-mov­ing cli­mate crises – presents a com­plex and inter­con­nected puz­zle,” she con­cluded. ​“It’s in the farmer’s best inter­est to build these resilient and sus­tain­able sys­tems, and doing so takes time.”

• Wild Farm Alliance