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

bird damage survey

WSDF BIRD slide

1. Estimate bird/rodent damage to dairies through farmer surveys

Six Whatcom County dairy farmers and 2 berry farmers were interviewed in 2014 to determine their perception of bird and rodent damage on their farms. Based on these interviews, we designed a one-sheet survey that was distributed at the November 2014 WSDF annual meeting in Clark County, and again at a WCD/WSU dairy workshop in January 2015 in Whatcom County. Additionally, an invitation to participate in an electronic version of the survey was distributed by WSDF in December 2014 to all dairy farmers in the state with an email address in the WSDF database, which totalled 250 email addresses (more than half of the 430 dairies registered in the state at that time). We received a total of 53 responses, which represented 21.2% of the 250 dairies with email addresses. Within Whatcom County, the response rate was slightly higher at 22%.

The survey had questions regarding basic farm parameters (herd size, acreage, crops, adjacent fruit acreage, feeding technique), perceived losses due to birds and rodents, history of pest control practices on the farm, and perceived effectiveness of various deterrent techniques.

Cows competing with starlings for feed at the feed bunk Starling night roost at a dairy

2. Measure numbers of pest birds and rodents at dairies and adjacent fruit fields through field data collection

Based on reported farmer observations, the European starling count increases in autumn and peaks in winter. Thus we modified our counting protocol to focus on the fall transition season and made initial counts at two farms throughout November 2014. Bird numbers quickly increased as the weather cooled. The scale of the problem was most evident where thousands of European starlings were roosting each night in dairy barn rafters, defecating throughout the barns and competing directly with cows for feed in feed bunks.

Through an interview process we chose 8 additional dairies spread throughout Whatcom County on which to conduct an earlier and more thorough set of bird counts in September and October 2016. All 10 dairies had known European starling populations, were willing to allow us access to their farm(s), and provided background information on their practices.

In 2016, we conducted intensive bird counts at all 10 sites as corn harvest was occurring and nighttime temperatures were cooling. Counts were made by visiting dairies twice per day, at least once per week, for at least 4 weeks. The researcher drove to a previously-selected viewpoint and remained in a car, using the car as a “blind” because birds tend to be more reactive to a person on foot than to a vehicle. Counts consisting of more than two dozen birds were estimates, made by viewing roosting spots, counting a fraction of the birds present, and then extrapolating based on the total area of the roost. The researcher spent 20-30 minutes onsite during each counting period. Counting visits were initially timed within two hours of sunrise and sunset at each dairy, but as it became apparent that some dairies had a different pattern in which birds visited temporarily at various times during mid-day, some mid-day counts were added at these dairies.

Birds other than European starlings, such as pigeons and Eurasian doves, were also noted and estimated, and raptors in the visual perimeter of the researcher were noted.

Though not insignificant, rodents were not perceived to be as much of a problem as birds by about half of dairy farmers according to our interviews and the survey. Although 49% of responding dairies indicated anywhere from a slight-to-serious problem with rodents, only about 26% of respondents listed a problem in the $1000/year or more range. For that reason, and due to logistics of rodent trapping, rodents were not counted. Many dairy operators felt that their barn cats kept rodents under control, and this appeared to be the case in our visits. However, at least one of the 10 dairy farmers participating in our bird count field data collection admitted to recent use of over-the-counter anticoagulant rodenticide due to a rat problem. Tragically, a neighboring farm cat known to be an excellent rat catcher ate one of these poisoned rats during the data collection period and became ill. Unfortunately, this cat was beyond hope of successful treatment and was euthanized by a veterinarian. The veterinarian performed a post-mortem that indicated internal bleeding as a cause of illness. Toxicology tests on liver tissue from the cat performed by the Washington Animal Disease Diagnostic Laboratory and the Michigan State University toxicology lab included a detailed anticoagulant scan to identify the specific fatal toxicant. An ingredient in a common over-the-counter rodenticide was identified and cited as the cause of death. 

3. Implement bio-control methods for managing problem birds and rodents in dairies/adjacent fruit

young kestrels

Dave Timmer placing kestrel nest box

Kestrel falcon in Whatcom County cherry tree

Pair of kestrels atop a nest box

Kestrel falcon nest boxes: In late spring/early summer 2014, we visited dairies in the two most dairy-intensive areas of the state (Whatcom County and Yakima County) to ascertain the feasibility of kestrel falcon nest boxes in those regions. Yakima County has more total dairy cattle and also had many kestrel nest boxes already in place, particularly in fruit orchards. The eastern side of the state generally has a far higher kestrel population than the western half.

There are more individual dairy farms on the west side of the state in Whatcom County than in Yakima County, but far fewer kestrel falcon nest boxes. Kestrel falcons have been in low numbers overall or in decline for at least two decades in Whatcom County. We therefore decided to focus on Whatcom County for implementing the nest box effort. Boxes were located in either dairy or berry farm areas, but usually in proximity to both. Some of the existing boxes dated back nearly 10 years and were in disrepair. We purchased enough new boxes and rebuilt, repaired, and relocated enough existing boxes in the county to reach 38 functional boxes by late summer of 2016.

GPS points were taken for each box and a map was created showing locations. Boxes were monitored in summer 2014, 2015, and 2016 to determine what species, if any, were present in the boxes. Kestrel counts were anecdotal in Whatcom County for other times of the year.

Note: although a translocation permit for orphaned falcons was in place during 2014-2015, no orphaned falcons became available for translocation from the east side of the state to the west side, so that enhancement possibility could not be pursued.

Barn owl nest boxes: In 2014, 2015, and 2016 we also monitored three owl boxes already in place on dairies. One of the successful owl boxes had a location with accessible Wi-Fi, so in 2014-2015 we installed a nestcam with live streaming on a web site for the public. This webcam was online for several weeks and owls with young owlets were present. The focal length of the camera lens was too close, however, so the visual was limited to close-ups of feathers. Eventually the owls ripped the wiring loose so that the camera shut down. We did not re-build the camera set up because we ran out of time and funding.

Hawk kites: Analysis of other data from a fruit damage study (see citation 7, Introduction) indicated this technique might only be minimally effective, so we did not implement it due to lower priority.

Raptor perches: All dairy farms working with us on bird counts had adequate raptor perches in the form of trees, dead snag trees, and/or utility poles already present so we did not need to install perches.

Carrion feeding station (carcass lower right) attracting bald eagles (in trees on left)

Carrion feeding: Over a period of four weeks in November and December 2014 and 2015, we placed stillborn calf carcasses and placentas within ½ mile of two dairy barns with starling populations to test for attraction of large raptors such as bald eagles and turkey vultures to the decomposing material. We counted raptors and watched for any subsequent effects of raptor presence on the starling populations.

Master falconer Tony Lapsansky with bird abatement falcon

Falconry. We obtained the cooperation of a commercial bird abatement falconer in flying his falcon at a dairy barn during fall 2015. Although starlings were not present on that date, we did see the effect of the falcon on pigeons that were present. A professional videographer filmed the event to include in a “virtual demonstration” video. Several dairy families were present at this demonstration. We conversed with the falconer on ideas for use of trained raptors in the dairy farm setting, and also on potential net-exclusion techniques that could be implemented in the future on barns that can be completely closed off as starling nighttime roosts. 

4. Estimate any changes in pest damage levels and raptor presence resulting from project implementation

In November and December 2016 we interviewed the 10 participating dairy farmers regarding perception of value/effectiveness of various biocontrols. We noted that in the worst starling depredation cases, further data would have to await the larger WSARE-funded project. Bird count data collected on these farms was compared for days on which raptors were seen in the vicinity, to days when raptors were not seen. We also interviewed attendees of the WCD Animal Health Dairy Workshop in November 2016 to gain their perceptions of biocontrol effectiveness. 

5. Host demonstration day at dairy

In September 2015 we invited farmers to a conference and subsequent demonstration (see 3 above) to view nest boxes and falconry, and discuss the overall pest bird problem. The demonstration of falconry and overall discussion centered on various low cost beneficial techniques for raptor enhancement.

To reach a broader audience beyond the demonstration day attendees, we also employed a professional videographer to create a video depicting bird problems on dairies and showing the potential benefits of kestrel falcon nest boxes, owl nest boxes, and professional falconry. This was posted on both WSU and WFF websites, including the WFF Facebook page, in January 2017.

Additionally, throughout 2015-2016, raptor demonstrations and presentations were held for 4-H groups, Ferndale Middle School and High School classrooms (including an “at-risk” group of students), Lynden High School and Lynden Christian High School FFA classes, two elementary school field trips, other agricultural events, and at the Northwest Washington Fair.

Personnel

Prof. Karen Steensma, Trinity Western University and Steensma Dairy, spearheaded the project, wrote reports, and made multiple presentations. Dr. Susan Kerr, Washington State University, served as technical advisor and veterinary advisor, and assisted with reports, presentations, survey design and hosting, and organization. Mr. Dave Timmer, natural resources biologist, and Mr. Tony Lapsansky, master falconer and bird biologist, helped investigate initial bird issues in Whatcom County and make presentations. Mr. Brian Garries, biologist, helped with data collection, GIS map creation, interactive presentations, and data analysis. Ms. Deanna Leigh, bird biologist, whose MS thesis was on effectiveness of kestrel falcons in cherry orchards, assisted with data analysis and mapping for the project. Mr. Ben Steensma, AA Mechatronics, was hired to assist with kestrel box installation and repair work and recording GPS points of nest boxes. Ms. Kira Banner and Ms. Joy Marconato, 4^th year Biology/Environmental Studies majors at TWU, assisted in interactive educational events by wearing a bald eagle costume and using bird puppets to discuss farmland birds with children and adults. Ms. Dina Roberts, 3^rd year Environmental Studies major at TWU, helped with data collection. Ms. Ellie Steensma, 2^nd year Agriculture Education major at Dordt College, helped with data collection, design and production of the laminated bird identification cards, interactive presentations, and bookkeeping. Mr. Brad Felger, professional bird abatement falconer / owner of Airstrike Bird Control, demonstrated falconry at the Lynden High School FFA Barn and at a local dairy.