Natural predators as a means to limit wildlife damage at the dairy-fruit interface

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2014: $24,287.00
Projected End Date: 12/31/2016
Region: Western
State: Washington
Principal Investigator:
John Steensma
Steensma Dairy

Annual Reports


  • Agronomic: corn, grass (misc. perennial), hay
  • Fruits: apples, berries (other), berries (blueberries), cherries, grapes, berries (strawberries)
  • Additional Plants: native plants
  • Animal Products: dairy


  • Animal Production: feed/forage
  • Crop Production: food product quality/safety
  • Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, participatory research, workshop, youth education
  • Farm Business Management: agritourism, value added
  • Natural Resources/Environment: biodiversity, habitat enhancement, hedgerows, riparian buffers, wildlife, hedges - woody
  • Pest Management: biological control, integrated pest management, prevention
  • Production Systems: holistic management
  • Sustainable Communities: urban/rural integration

    Proposal summary:

    We propose to estimate bird and rodent damage on dairies adjacent to fruit in Whatcom County in order to increase the presence of natural birds of prey on these dairies over one to two years; to re-survey damage after use of tested techniques; and to host on-farm demonstrations highlighting the results. Wildlife damage to fruit crops in Washington and Oregon has recently been cost-estimated from $400- $3,000/acre/year in grapes, cherries, blueberries and apples (1). With increased blueberry acreage in Whatcom County and other western counties over the past decade, dairies are increasingly located adjacent to blueberries. The invasive European starling is responsible for much damage to both fruit and stored dairy grain and forages, but other birds, and rodents, are also implicated. Though not rigorously examined, losses to dairy operations range from $2,000-$10,000/herd/year or more with a typical 1,000-bird starling flock easily consuming a ton of silage each month (2). The pattern for starlings includes roosts at dairies, where high energy foods are available at open faces of bunker silos, in grain rations placed before cows in the feeding area, and in manure lagoons. Starlings on dairies then take advantage of ripe fruit during blueberry season. Similar patterns may be seen where livestock feeding occurs near other fruit crops (e.g. beef feedlots/dairies near Yakima cherry orchards). Rodent problems include rats eating corn and grain on dairies and voles chewing roots and bark in fruit crops (3). Use of scare tactics such as propane cannons and bird distress calls are widely perceived to be ineffective, while disturbing both farm and non-farm neighbors. Lethal management methods include trapping, shooting and poisons. Farm employees may have little time or ability to distinguish between "pest" vs. "beneficial" birds, sometimes using a guiding principle that "the only good bird is a dead bird." Starling and rodent traps can provide removal of individuals but may inadvertently trap beneficial birds, such as swallows and raptors, or harm other non-target species. Poisons have potential to move through the food chain, harming beneficial species such as raptors (4,5). We will develop a dairy interview/survey tool in order to quantify annual loss of feed through direct removal and fecal contamination, and time and money spent on shooting, trapping, poisoning and other techniques. Adjacent blueberry growers will also be interviewed about damage. Our dairies and others with proximity to fruit crops will be chosen for implementation of ecologically sustainable biocontrol techniques, including installation of barn owl and kestrel falcon nestboxes, raptor perches and hawk kites. We will also connect area falconers to dairy owners willing to allow falconers to fly their birds in open fields. Additionally, an existing federally-permitted translocation program for placing young kestrels in western Washington agricultural fields may be utilized in order to habituate kestrels on one of the dairies. Placement of carrion – undiseased dairy placentas and stillborn calves – for natural decomposition in sufficiently isolated fields (under Washington State Department of Agriculture regulations) will be suggested as a means of keeping larger raptors in the area. Cessation of rodenticide use and trapping will be requested on participating dairies, in order to minimize risk of secondary poisoning or trapping of raptors. Dairy owners and employees will be instructed in bird identification in order to prevent shooting of beneficial and non-target species. We will also encourage adjacent fruit growers to discontinue rodenticide use and shooting of non-target birds. Bird counts and small mammal trap counts will be taken by a research technician at each of the chosen dairy field sites before, during and after the implementation of the biocontrol techniques. Each dairy farmer will be asked to estimate damage levels and economic losses again at the end of the project. Participating farmers will also provide their own perceptions of effectiveness of the various techniques attempted. Based on these numbers (pest counts, farmer estimates of damage and farmer perception of effectiveness), a few techniques will be selected for a demonstration event to which area dairy and berry producers will be invited. Area 4H and FFA youth will help promote, conduct and publicize this project. Education will be through the WSU Extension webpage, Facebook, YouTube, a nestbox webcam, a brochure identifying ecologically-sustainable techniques and a bird identification card. The expectation is that enhancement of habitat for birds of prey, or other means of providing "natural" controls for pest birds and rodents, will not only prove economically beneficial for farmers, but will also reduce direct mortality of raptors (6). Farmers may be able to save money, increase public perception of the value of agriculture for wildlife species and improve the overall rural community through these efforts.   1. Anderson et al 2013. Bird damage to select fruit crops: The cost of damage and the benefits of control in five states. Crop Protection 52:103-109   2. Johnston 2013. Coping with sky-high feed. Successful Farming (Nov):BI1-2   3. Ashkam 1988. A two-year study of the physical and economic impact of voles on mixed maturity apple orchards in the Pacific Northwestern US. Proceedings Vertebrate Pest Conference 13:151-155   4. Rattner et al 2011. Acute toxicity, histopathology, and coagulopathy in American kestrels following administration of the rodenticide diphacinone. Environmental Toxicology & Chemistry 30:1213-1222   5. Thomas et al 2011. Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterisation of toxic liver concentrations and implications for predatory bird populations in Canada. Environmental International 37:914-920 6. Baldwin et al 2013. Perceived damage and areas of needed research for wildlife pests of California agriculture.  Integrative Zoology (in press)

    Project objectives from proposal:

    1. To estimate bird/rodent damage to dairies through farmer surveys:   a. May 2014: interview 6-12 dairy farmers to ask whether they have measurable losses to these pests, and if so, what amounts and categories of loss exist (feed, destruction of silage tarps, sanitation and disease issues, costs of trapping, poisoning, shooting)   b. May 2014: based on above interviews, design and circulate an email/mail survey to all dairy farmers in Whatcom County regarding basic farm parameters  (herd size, acreage, crops, adjacent fruit acreage), perceived losses to birds and rodents; use results to choose and interview adjacent blueberry growers; identify final cooperators and sites   2. To measure numbers of pest birds and rodents at dairies and adjacent fruit fields through field data collection:   a. May 2014-December 2015: conduct monthly bird point counts on at least three dairies/adjacent fruit fields, in order to estimate number of species, and numbers of each species present, accounting for seasonal variations and responses to biocontrols (below).   b. May 2014-December 2015: conduct 24-hour small mammal trapping exercises on at least three dairies/adjacent fruit fields. Repeat quarterly to account for seasonal variations and responses to biocontrols (below).   3. To implement bio-control methods for managing problem birds and rodents in dairies/adjacent fruit:   a. May-July 2014, March-July 2015: install sets of at least one to two kestrel boxes + one owl box/dairy on at least three dairies; monitor through field observations and spy-cam (small video camera on telescoping pole). Recruit 4H and FFA youth for volunteer assistance in monitoring boxes and installing a nestcam.   b. June 2014-December 2015: Identify existing raptor perch sites in the area (utility poles, tree snags in riparian areas); work with cooperating farmers to install additional perches and hawk kites as needed; recruit 4H and FFA youth for moving hawk kites and monitoring assistance   c. July 2014-October 2015: Work with local master falconers and licensed bird abatement falconry company to connect falconers with dairy owners willing to allow regular falconry flights on their land. Recruit 4H and FFA youth to document falcons with photos/videos.   d. June-July 2014/2015: During kestrel nesting season, work with existing kestrel translocation project to locate suitable dairy field site if young kestrels become available.   e. August 2014-July 2015: Identify parameters for natural decomposition sites for dairy carrion (placentas, stillborn calves); monitor raptor numbers at any sites so utilized by dairies.   4. To estimate any changes in pest damage levels and raptor presence resulting from project implementation:   a. February-March 2016: Repeat survey of participating dairy and berry farmers, including questions regarding perception of value/effectiveness of various biocontrols.   b. February-March 2016: Analyze data from bird and small mammal counts, and from nestbox, hawk kite and perch monitoring.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.