Birds on Berries and Dairies

Karen Steensma, Trinity Western University

Susan Kerr, Washington State University

Amber Adams-Progar, Washington State University

Figure 1. Kestrel hunting in Whatcom County blueberry field.

WSU researchers have teamed with Trinity Western University, Western Washington University, and Oregon State University since 2012 to study management of pest birds in the Pacific Northwest. Several berry growers in northwest Washington and various eastern Washington fruit growers are participating in the project.


The team has already published results of economic analyses that show blueberry growers lose $4.6 million annually to birds in the state of Washington alone. Damage estimates are around 10% even with various bird deterrent methods in place, and could reach 50% or more if no deterrents are used in areas with heavy bird pressure. Development of a cost-benefit analysis tool to determine the most cost-effective deterrent technique for various fruit value is one of the project’s upcoming objectives.


The close proximity of fruit crops and dairy operations throughout the region, and particularly in Whatcom and Skagit Counties, the lower mainland of British Columbia, and the Yakima area, creates a potential paradise for invasive European starlings. Starlings find a steady source of feed from silage stacks and commodity barns on dairy farms throughout fall and winter, and are able to switch to “dessert” during summer ripening of cherries, apples, blueberries and grapes.


Other native birds such as American robins and crows can also cause fruit damage. Though extensive data sets are still being analyzed, initial findings indicate that propane cannons and audible distress callers are less effective than netting or falconry. Other techniques with mixed results thus far include “air dancers” (inflatable moving scarecrows), hawk kites, and bird repellent sprays. Kestrel falcon nest boxes show the most promise in eastern Washington cherry orchards, where the native kestrels are in high numbers.  Kestrel box occupancy has also begun to occur in Skagit and Whatcom Counties over the past several years, with anecdotal evidence of protection of blueberries.


This research program has been funded by the USDA Specialty Crop Research Initiative and Environment Canada. Other North American collaborating institutions are Michigan State University and Cornell University. For the full scope of the project including links to findings in various crops, visit


Additionally, three Whatcom County dairies have undertaken a farmer-led project funded by USDA Sustainable Agriculture Research and Education to study the impact of both pest birds and beneficial birds, such as kestrel falcons and barn owls, on dairies. Dairies that have large starling populations--especially dairies that serve as night roosts for starlings--may face annual damages of $50,000-100,000 per dairy.


Future research will focus on prevention of starling roost establishment; use of native raptors, falconry, drones on dairies, and modification of agricultural landscape factors. Farm operators interested in participating in future projects are welcome to contact team leaders below.



The Economic Impact of Bird Damage to Select Fruit Crops in Washington Factsheet:


Vertebrates: Birds Info on WSU Whatcom County Extension:



Karen Steensma, Trinity Western University:

Susan Kerr, Washington State University: or 360-848-6151.

Amber Adams-Progar, Washington State University:







Figure 2. Professional falconer.

Figure 3. Air dancer in cherries.