Bird damage is an increasing problem in the Northeast, particularly for sweet corn growers. The suburban landscape provides ideal habitat for flocking birds such as crows and starlings, which roost in trees and structures but feed in open areas. At the same time, the peri-urban location limits farmers’ control options. Many growers use propane cannons and other noise makers to scare birds as this method best combines economy and efficacy. However, the constant barrage of noise from the cannons annoys farmers’ neighbors for miles in every direction. In several communities in Rhode Island the conflict between farmers and their neighbors has expanded into the political realm, where it is threatening the Right to Farm Act.
Automated laser “scare crows” which use moving green laser beams to frighten birds have been used to prevent bird damage to vineyards and orchards in Europe and elsewhere, and anecdotal reports are positive. One sweet corn grower in Bristol, RI used a laser scarecrow in his fields in 2016, and reported that bird damage decreased to near zero. However, no scientific data exists on the efficacy of automated laser scarecrows, and they have not been tested in replicated or controlled experiments in the Northeast. The goal of this project was to measure the efficacy of automated lasers for protecting crops from bird damage, and to collect data needed for farmers and regulators to determine whether lasers are a feasible alternative to propane cannons.
The project team developed a lower-cost automated laser scarecrow designed for use in peri-urban areas, and tested it in sweet corn fields during the summer of 2017. In a controlled trial on the research farm, the scarecrow-protected plot averaged 14.6 damaged ears per acre over five sampling dates, while the unprotected plot averaged 48.4 damaged ears. The difference was statistically significant (p = 0.005) but overall bird damage levels were not economically significant. In commercial sweetcorn fields on five cooperating farms bird damage in laser-protected plantings never exceeded 10% of the potential marketable yield. The cooperating farmers protected entire plantings, and did not use unprotected control plots. However, all fields had a history of bird problems, and the farmers reported that unprotected plantings in 2017 suffered yield losses as high as 80% due to bird damage. These results show that automated green lasers are effective at repelling blackbirds and starlings from sweet corn fields, and that the lasers are more effective than propane cannons. The laser scarecrow units developed by URI are able to protect a circle with a 300ft radius against blackbirds and starlings. When laser scarecrows are properly deployed, the impact is limited to the field being protected, making them a good alternative for peri-urban areas. Farmers and regulators are very excited by the potential of laser scarecrows and further tests in multiple crops are planned for 2018.
In 2014 the University of Rhode Island and the Rhode Island Division of Agriculture began collaborating on a search for alternatives to propane cannons for controlling bird damage in sweet corn. The most promising solution appears to be automated laser “scare crows” which project green laser beams over and through the canopy to frighten birds. Several commercial units are available on the market, and anecdotal reports from growers are largely positive. However, there have been no actual studies assessing the effectiveness of lasers for bird control in sweet corn, and no tests on any crops in the Northeast. The goal of this project is to measure the efficacy of automated lasers for protecting crops from bird damage, and to collect data needed for farmers and regulators to determine whether lasers are a feasible alternative to propane cannons. The project will address the question
“Are lasers effective at repelling birds from sweet corn fields?”.
The objectives are to determine whether lasers will reduce bird damage to acceptable levels relative to a control, to determine the density of laser units needed, and to identify the bird species which can be effectively repelled.
Bird damage is a serious problem for farmers in the Northeast, particularly in sweet corn. Even low levels of damage require increased labor to grade out the damaged ears after harvest, largely negating the economic advantages of mechanical harvest. Sweet corn is a major vegetable crop in the Northeast, with significant production in all states except West Virginia. In 2014 55,700 acres of sweet corn, valued at over $144 million, were harvested in the Northeast. Official data on losses due to bird damage are not available for this region, but farmers in Rhode Island estimate that bird damage costs them $800 per acre in severely affected fields.
Crows and starlings are the primary pests in sweet corn, although blackbirds, grackles, and sparrows can also cause problems. A combination of propane cannons and occasional hunting of birds is the most widely used control method, as it is affordable and fairly effective. However, in peri-urban areas farmers’ use of bird cannons are increasingly creating conflicts with non-farm neighbors who object to the noise of the cannons, which may discharge as often as every five minutes from sunrise to sunset during a sweet corn harvest season stretching from mid-July to mid-October. Much of the sweet corn acreage in the densely populated states of the Northeast is in peri-urban areas. In Rhode Island the conflicts have reached the point where several communities have threatened to sue the state in an effort to have propane cannons excluded from protection under the Right to Farm legislation. Once Right to Farm protection is removed, cannons could be prohibited under existing noise ordinances.
Other strategies currently recommended for preventing bird damage to crops include netting, reflective Mylar tape, chemical bird repellants and falconry. Netting and reflective tape are impractical for many sweet corn growers because of the labor cost of setup and removal, the large acreages, and the likelihood of interference with field operations. Chemical bird repellants have not been effective for sweet corn in research trials or on-farm. Falconers are scarce and expensive in peri-urban areas, charging as much as $600 per day for their services.
In 2014 the University of Rhode Island and the Rhode Island Division of Agriculture began collaborating on a search for alternatives to propane cannons for controlling bird damage in sweet corn. The most promising solution appears to be automated laser “scare crows” which project green laser beams over and through the canopy to frighten birds. Several commercial units are available on the market, and anecdotal reports from growers are largely positive. However, there have been no actual studies assessing the effectiveness of lasers for bird control in sweet corn, and no tests on any crops in the Northeast. The goal of this project is to measure the efficacy of automated lasers for protecting crops from bird damage, and to collect data needed for farmers and regulators to determine whether lasers are a feasible alternative to propane cannons. The project will address the question “Are lasers effective at repelling birds from sweet corn fields?”. The objectives are to determine whether lasers will reduce bird damage to acceptable levels relative to a control, to determine the density of laser units needed, and to identify the bird species which can be effectively repelled.
Researchers with the USDA-APHIS NWRC have found that low power red laser beams are effective against roosting cormorants, geese, crows, and vultures but not against roosting passerine birds, and neither red nor green hand-held lasers were effective at permanently dispersing roosting redwing blackbirds from cattail swamps in North Dakota. At many airports employees wield hand-held lasers to dissuade birds from feeding near runways, but automated lasers are a more practical option for farmers. No published test results exist for automated lasers, or for daytime use of lasers against actively feeding birds. However, two models of automated green lasers are being marketed for repelling feeding birds from agricultural fields, orchards, and industrial sites. The manufacturers’ websites contain testimonials from grower trials of these lasers, primarily in fruit and berry orchards and vineyards. The Dutch company Bird Control Group LLC manufactures the Agrilaser Autonomic, which was adapted from lasers used at airports and is currently being tested in blueberries by researchers at Oregon State University, and in other crops by researchers at Washington State University. Several sweet corn growers in Rhode Island have purchased the laser system produced by Carpe Diem Technologies in Vancouver, British Columbia, but this system has never been formally tested. In 2016 we tested a prototype laser scarecrow on the research farm at the University of Rhode Island. The unit reduced bird damage from 3.2% of sweet corn ears to less than 1% of ears when the primary birds present were crows and starlings. Damage levels were below 1% in laser-protected commercial sweetcorn fields in Cranston, RI and Bristol, RI but the growers protected all of their corn so it was not possible to determine the level of bird pressure.
The aim of this study is to collect data on the efficacy of laser scarecrows in sweet corn to support extension educators, crop consultants, and regulators advising growers. For growers who currently use propane cannons, switching to lasers would allow them to reduce noise complaints and conflict with neighbors without dramatically increasing crop losses or protection costs. Sweet corn growers who tolerate bird damage to avoid conflict with neighbors would be able to reduce their crop losses. All peri-urban farmers would benefit from removing the threat of lawsuits to force changes to Right-to-Farm laws, as a successful lawsuit would open the door to loss of protection covering many other aspects of agriculture, from deer fencing and roosters to traffic-generating agritourism events. Commercially available laser scarecrows start at $3,000 for a unit able to protect up to 20 acres, while a farmer would be able to construct a unit similar to our research laser for less than $400 including the battery and support structure.
This project was divided into three sub-projects, each of which will be reported on separately:
- design and assembly of laser scarecrow units
- controlled efficacy test on URI Research Farm
- tests on commercial farms
Design and Assembly of Laser Scarecrow Units
Assembly of the experimental laser scarecrows began in late May, continuing throughout the month of June and into early July. Steps in the assembly process included making the unit housing by modifying plastic 5-gallon buckets, soldering together prototype circuitboards, building the rotating arm for mounting the laser, and attaching all the electrical and mechanical components within the unit housing. It was also necessary for the student research assistant tasked with assembling the units to develop some crucial skills, such as correct methods for soldering, before engaging in the pertinent steps of the assembly process. After assembly, all units were tested and determined to be fully operational before being deployed. Seven units were constructed and deployed in 2017.
Over the course of the summer, it became necessary to make numerous visits to growers to adjust, relocate or repair the units. Deploying the units to commercial operations provided an opportunity to test the durability of the mechanical components that were used, and it became clear that some pieces were more resilient than others – for example, every unit deployed to commercial growers required at least one servo motor replacement, while the stepper motors that were used functioned properly in all of the units all summer long. This created a fairly steady cycle of exchanging faulty units for functional ones at commercial farms, running diagnostics on the cause of unit failure, repairing or replacing the malfunctioning part, and again exchanging the repaired and functional unit for a faulty one. These visits also granted the opportunity to discuss the ideal height and location of the units with growers, and to familiarize the growers with the range of variable settings, such as rotational and oscillatory speed, that the units were equipped with. Feedback and anecdotal reports from the growers indicated that, when deployed properly, the units were highly effective at preventing bird damage. The insights gained from the growers also proved valuable in determining how best to deploy the unit in the controlled experiment at the Gardiner Crops Research Center.
Controlled Efficacy Test
The objectives of the controlled test were to test the scarecrow in a situation where the protected and unprotected plots were identical except for the laser scarecrow, and to determine whether effectiveness of the scarecrow decreased over time. The experiment was conducted at the Gardiner Crops Research Farm on the URI campus in order to have complete control over the field layout and avoid complications from other bird-control strategies farmers may be using. Preparation for the controlled experiment at the Gardiner Crops Research Center began in early June. Two acres of sweet corn were planted with the same seed mix, one at each end of a three-acre field. Each plot was 300 ft. long and 150 ft wide, with a 5 ft spray alley down the center of the plot. Corn was seeded with a spacing of 30 inches between rows, and was thinned to 12 inches between plants in the row. Fertilization followed extension recommendations. Callisto and metalachlor herbicides were applied at planting to control weeds. Seedling insect and disease problems were prevented with treated seed. Corn was not sprayed to control corn earworm (Helicoverpa zea). The medial acre of the field was planted with a cover crop. The seed mix contained eight different varieties of bicolor sweet corn, ranging in maturity from 72 to 86 days after planting. The field was situated in the northwest corner of the Research Center’s land, meaning that it was immediately adjacent to high deer fencing on the north and west – this fencing appeared to be an attractive place for starlings and other birds to perch throughout the summer. Sweet corn harvest began August 17 and continued until September 8. Once the beginning of the maturity window for the experimental corn plantings had been reached, a scarecrow was equipped with a bucket-fabricated beam shield and deployed next to one acre of sweet corn. The beam shield prevented emission of the laser beam through more than 180 degrees of arc, meaning that the unit would protect only one of the two planted acres at any given time. After approximately seven days, the number of corn ears in each acre was counted during hand harvest – all damaged ears were removed from the field to prevent future confusion – and recorded.This was deemed a “counting event.” After each counting event, the shielded unit was repositioned to protect the acre that had previously been unprotected. This was done in order to randomize the experiment and account for any possible preference in field that the birds may have had. After four to seven days, depending on the rate of bird activity, another counting event would take place. The range in maturity dates of the sweet corn allowed the data collection period to be more protracted than if the acres had been planted to a single variety with uniform maturity.
Tests on Commercial Farms
We tested the scarecrow in commercial sweetcorn fields in Lakeville, MA, and Bristol, Warwick, Cranston, Scituate, and Richmond, RI. The first trial began July 1 and tests continued through September. It proved impractical to protect only a portion of each corn planting, since the plantings were long and narrow with rows running the length of the field, and the scarecrow protects a circular area. Thus no unprotected control was used for the commercial tests. Instead results were compared to historical levels of bird damage for each field, and to damage levels in unprotected fields in the vicinity. The cooperating farmers collected data on the extent of bird damage at harvest for each planting. Project personnel collected data on bird damage levels in a Warwick field that contained multiple plantings of first-early corn that was harvested by hand. All other plantings were machine harvested. Project personnel visited each farm multiple times during the season to ensure that scarecrows were properly set up and to records data on the species of birds present in and around the fields.
The laser scarecrow was also tested in a vineyard in Johnston, RI, and was used to protect winter rye cover crop from geese in October and November in Lakeville, MA.
Design and Assembly of Laser Scarecrow Units
We constructed and field-tested 7 laser scarecrow units. In general the units functioned well, although there were problems requiring repair during the growing season. Designs for the 2017 version of the scarecrow have been made publicly available at https://sites.google.com/view/urilaserscarecrow/building-a-laser-scarecrow?authuser=0. The site went live in mid-December. Based on 2017 testing, we have made several modifications to the laser scarecrow design for 2018. We filed a provisional patent application in October 2017, and are in discussions with the University of Rhode Island and potential manufacturers about commercializing the scarecrow technology to make it available to growers who lack the skills to build their own units.
Attached are design, image and component files found at the above website. The CAD folders for the Belt Drive, Bucket Mount, IR Cap, Laser Hanger, and Protoboard clip are at the above website. The coding for the software is found at https://github.com/davidhbrown-uri/laser-scarecrow-arduino
Controlled Efficacy Test
Wet weather in May delayed sweet corn planting at the research farm until mid-June, with the result that the corn did not begin to mature until mid-August. This was after the peak season for bird damage, so bird pressure was low. However, significantly fewer ears suffered bird damage in the field protected by the laser scarecrow Bird-damage-in-controlled-trial.
There was no indication that birds became accustomed to the laser over time.
Tests on Commercial Farms
The laser scarecrow worked extremely well on the commercial farms. Ken Elliot in Lakeville, MA reported that 5 to 10% of ears were damaged by birds in protected fields. Historically the lowest damage levels in those fields were around 40%. Other growers reported that there was so little damage in protected fields that the culled ears were not worth counting. Bird pressure was high in RI in 2017, with growers around the state reporting levels in excess of 80% on unprotected sweet corn fields. At one of Vinny Confreda’s fields in Warwick the earliest planting of sweet corn was left unprotected and damage was close to 100%. When a laser scarecrow was placed in that field, damage on the later plantings dropped to less than 10%. Similarly, in August Vinny had 3 fields maturing at the same time, but only two laser scarecrow units. The unprotected field was heavily damaged, with minimal damage in the protected fields.
The laser scarecrow was so effective on commercial farms that we were forced to change our experimental design and protect entire fields. We were not able to set up replicated tests using piles of harvested corn because Jim Lawson received so many requests for scarecrows that we had to limit growers to one URI unit per farm. The scarecrow also proved effective at keeping starlings and flickers out of grapes, and at protecting emerging cover crops from depredation by Canada geese.
We found that laser scarecrows are extremely effective at protecting sweet corn from starlings and blackbirds, and that they have potential for use in other crops and against other species of birds. In fresh market sweet corn losses were reduced to less than 10% of first ears, as compared to losses exceeding 80% in unprotected fields. Laser scarecrows appear to offer better protection than propane canons, and they avoid conflicts with neighbors over noise pollution. Two of the cooperating farmers in this study used commercially available laser scarecrows designed for protecting orchards, in addition to using the URI-designed units. The commercial units cost ~$3,000; the area that can be protected depends on field layout and topography. In much of New England one scarecrow is unlikely to protect more than 5-10 acres of corn, but the scarecrow can easily be moved between fields as plantings are harvested and new plantings mature.
The number of corn plants per acre depends on spacing within and between rows, and spacing requirements depend on the cultivar. However, 16,000 plants per acre is not unreasonable for main-season cultivars. Each plant should yield at least one marketable ear. Yields in New England for 2011-2015 averaged 8,900 ears per acre, suggesting 45% of the potential crop was lost. Reducing losses to 10% by adopting laser scarecrow technology could increase marketable yields by 5,500 ears per acre, increasing revenues by $1,800 per acre using a conservative estimate of $4 per dozen ears. Increased marketable yields could return the investment in laser scarecrow technology in just one year for farmers with severe bird problems.
Adopting laser scarecrow technology would offer benefits in addition to increased marketable yields in sweet corn. The biggest benefit is improved relations between farmers and their neighbors, as propane cannons are a major source of farm-town conflict. Increasing marketable yields per acre could allow farmers to rotate some sweet corn acreage out of production and provide opportunities for cover cropping to build soil health.
Education & Outreach Activities and Participation Summary
The results of our research were presented as part of the Northeast IPM online conference in November 2017 (est. 50 service providers attended), at the New England Vegetable and Fruit Conference in Manchester, NH in December 2017 (80 attendees) and at the Western New York Vegetable Conference in January 2018 (estimated 50 attendees). A workshop on bird control in sweet corn held in Rhode Island in March 2018 was attended by all the major sweet corn producers in the state, as well as some from Connecticut and Massachusetts (30 attendees total). The presentation and proceedings paper from the New England Vegetable and Fruit Conference are available online at https://newenglandvfc.org/past-conference-proceedings-presentations/2017-proceedings-and-presentations.
Results were also presented at the 2017 URI Twilight meeting, and Jim Lawson presented the laser scarecrow technology to numerous state and town officials in Rhode Island.
Jasper Romero presented results from the controlled trial at the URI undergraduate research poster session in December 2017.
Farmers reported gaining awareness of laser scarecrow technology. Numbers are high because this is a relatively new technology which had not been used at all in the Northeast before 2016. The information on laser scarecrows available through URI Digital Commons has been downloaded 36 times by people in the Northeast, and 24 times by people in other parts of the world. Over a dozen farmers have expressed interest in using laser scarecrows in their fields in 2018.
Farmers are very excited about the potential of laser scarecrows to protect sweet corn and other crops from birds. At present the primary factor limiting adoption is that there are no commercial laser scarecrows designed for use in sweet corn. We published the plans for the scarecrow units used in this study, and at least four farmers are having units built for them. In one case, the farmer partnered with the robotics club at the local high school, creating a project that benefits the students as well as the farmer. We have also developed scarecrow kits which can be assembled without any skills in digital electronics (which few farmers seem to have); twenty kits are available for the 2018 sweet corn season.
This project has led to several collaborations which will hopefully result in new commercial technology available to growers. We are collaborating with Bird Control Group LLC to test their commercial Agrilaser Autonomic units in blueberry fields. They are the major commercial source of bird deterrent laser technology, and are expanding their network of distributors in the US. At present they are focusing on bird control in soft fruits. We are providing laser scarecrow kits to Charles Bornt of Cornell Cooperative Extension to test in sweet corn fields in upstate New York. We have also made connections with wildlife scientists working on bird control at the USDA and Purdue University, and are writing proposals to fund collaborative research into how the lasers effect the birds.
This study set out to determine whether laser scarecrows were effective at protecting sweet corn from blackbirds and starlings. The scarecrows were extremely effective in the fields in which we tested them. The results were sufficient to excite the farmers. However, we encountered difficulties with the methodology that prevented us from obtaining results that would pass peer-review.
- On the research farm, where we were best able to control for other factors influencing bird damage, overall bird damage levels in the control plots were too low to be economically significant. This is likely because the research farm is located in an area with high landscape diversity, good hawk habitat, and limited food sources for flocking birds.
- We had a limited number of scarecrow units, and our Division of Agriculture partner’s priority for placing those units was based on politics more than science. This led to an increase in the number of farmer partners (5 rather than 2 as planned) but meant that we could not replicate within farms.
- All of the farmers machine-harvested most of their corn. Plantings are long and narrow, and there was no good way to split the planting into treatment and control plots, especially since the entire planting is harvested at once. We relied on farmers to report the bird damage from these plantings, which we compared to the farmer-reported historical damage from the same fields in previous years, but the farmers do not always distinguish between bird damage and other causes of lost yield in their records. The data are more anecdotal than is desirable. However, the reported damage with scarecrows was less than 10% in all plantings, while historic damage exceeded 40% in all fields.
We will be conducting additional field tests in 2018. We have arranged to conduct controlled trials on two local farms which hand harvest their corn and have high levels of bird activity. Project personnel will collect damage data on these farms. We will also be expanding the number of farms where we collect farmer-reported data, relying on a large sample size and geographical distribution to compensate for lack of control over factors affecting bird activity.
We have anecdotal reports suggesting that lasers are effective at protecting sprouting grains (especially winter rye) from geese; we will be conducting controlled trials in Fall 2018. We are also conducting controlled trials in blueberry and expanding our work with grapes.
Future research is needed to determine how the birds perceive the lasers, and the threshold above which laser beams can cause eye damage in birds under field conditions. We have been using 50 mW lasers with a beam diameter of 14 mm; commercially available units use 100 to 500 mW lasers with a beam diameter of 40 to 50 mm. All of these units are regulated as class IIIB, capable of causing eye damage to humans under laboratory conditions. Research is needed to determine the minimum power and maximum beam diameter effective in controlling birds so as to minimize risks. Little is currently known about how foliage affects the dispersion of green laser beams. More research is also needed on the safety of class IIIB lasers used outdoors in daylight, as all current safety guidelines assume that the laser is being used under low light conditions.
Laser scarecrows could benefit fresh-market sweet corn growers everywhere, with particular benefit to those in peri-urban areas where noise pollution from propane cannons is a problem.