When the Sown Crows Ruin the Yield

Attacking Cornfields: How Crows Wreak Havoc on Farms

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Harvest ruination through jaunty ravages - When the Sown Crows Ruin the Yield

When crows swarm farmlands in droves, it can lead to a devastating loss for farmers with entire crops being destroyed. Traditional methods like scarecrows may not suffice in dealing with these intelligent birds, so the State Office for the Environment (LfU) has teamed up with the Weihenstephan-Triesdorf University of Applied Sciences (HSWT) for a pilot project. Various deterrents are being tested to limit crop damage.

Test runs began in early April, focusing on heavily affected regions such as Straubing, Erding, and Asbach-Baumheim (Donau-Ries district). More farmers are welcomed to join. The crow colony in Straubing, based near the Tiergarten, boasts about 1000 breeding pairs, according to an LfU spokesperson.

Favored Food Choices

The pressure on the grounds is immense where crows' favorite foods, such as earthworms, are scarce. If no earthworms are available, crows uproot plants to munch on the larvae residing on roots. They also devour pumpkin seeds and cucumber heads.

Conventional precautions like scarecrows or CDs hanging on wooden crosses couldn't save the crops, as crows could adapt to these measures due to their keen learning ability. As a result, kites, balloons, and crow decoys are being utilized more in project fields, as explained by Nils Teufel, an HSWT scientific employee.

Authorized Shooting As An Option

Shooting is another method being tested, with exemption permits for lifting the hunting ban granted to the cities and districts of Straubing. However, reproducing crows are off-limits for hunting, and no crows have been eliminated since the project's start.

Since crows resemble rooks, hunters need special permits to shoot them on project fields to prevent mistaking one for the other, said the LfU spokesperson.

Crow Trouble on Protective Field Nets

Johannes Frank, a project participant in Straubing who grows herbs like Primula veris, showcases photos of decimated fields. Even protective nets covering young plants are ineffective against crows, who peck holes in them. Humans and vehicles fail to scare the birds off; they merely trail the planting machine and dig up the seedlings again.

To cultivate the field, six workers put in overtime from morning until evening for four days. The damage caused by crows cannot be covered. Moreover, his customers anticipate timeliness, so he has placed special kites from LfU on his field, alongside plastic decoys of dead crows. These decoys are designed to scare crows but are so realistic that passersby have already contacted the police believing they were actual dead birds, as per an LfU spokesperson.

While there is an adaptation factor with these deterrent methods, Frank emphasizes the first 14 days post-planting are crucial for repellent plants. In contrast to previous years, crows didn't quickly turn to the decoys this season. "No guarantees," admitted Nils Teufel.

The project will end with harvest, and evaluations are planned by year-end. In Dachau, as part of the LfU project, experiments to discourage crows in urban areas have been conducted. Fourteen birds were shot, and 83 nests were extracted. Findings from this city project are still unavailable.

Bavarian State Association for the Protection of Birds (LBV) opposes the project, acknowledging the increasing trend of eliminating wildlife instead of seeking solutions that also prioritize bird and animal welfare: "When tensions arise between coexisting with wild animals, the call for eradication arises faster than hunting for solutions that respect species and animal conservation."

Urbanization, loss of natural habitats, and a lack of undisturbed tree groups for nesting are key factors that force crows to move to cities, according to the LBV: "Cities become the last resort for them."

• crop protection
• crows
• birds
• harvest
• Straubing
• plants
• agriculture

Deeper Understanding:

The effectiveness of deterrent methods in reducing damage caused by crows in regions such as Straubing, Erding, and Asbach-Baumheim (Donau-Ries district) varies depending on the technique used. Modern automated systems have exhibited high efficiency, offering improved crop protection compared to traditional scarecrows and repellents.

Efficiency of Preventive Strategies

Advanced Automated Systems These multi-sensor systems combine motion sensors, sound transmitters, and lights to actively detect and repel birds, covering areas up to 0.75 hectares. Utilizing PIR sensors with a detection range of approximately 50 meters and wide detection angles, they trigger stimuli like sounds and lights when birds approach, offering sustained bird deterrence [2].

Static Scarecrows Ancient in their use and outdated, these stationary figurines lack movement, sound, and light stimuli to consistently deter birds, leading to habituation and reduced effectiveness [1][2].

Laser Deterrents Laser-based repellents project moving beams of light that irritate birds and drive them away without causing harm. Their utilization can reduce crop losses by up to 60%, offering a highly effective solution when properly deployed [3].

Repellent Sprays Chemical repellents may provide temporary protection, yet their efficacy tends to wane quickly and may harm pollinators, limiting their utility on farms [4][5].

Trapping Adjusted captive traps have proven successful in capturing large numbers of problem birds. However, they are more appropriate for population management rather than immediate crop protection [5].

Ecological and Avian Population Implications

• Non-Lethal and Ethical Solutions: Advanced automated systems, laser deterrents, and chemical repellents are designed to repel rather than harm birds, preserving local avian populations while protecting crops [2][3][4].
• Habituation Risks: Birds may learn to disregard static or monotonous deterrents like traditional scarecrows or some frightening devices, increasing the risk of crop damage unless deterrents are switched up or combined dynamically [1][5].
• Selective Pressure: Repeated deployment of deterrents could influence bird behavior, potentially increasing feeding in less affected regions, altering local ecosystem dynamics.
• Environmental Safety: Advanced automated and laser deterrents have minimal ecological impact compared to repellent sprays or lethal controls, making them preferable environmental choices [2][3].
• Population Regulation: Trapping, while effective for reducing local bird numbers, must be managed carefully to minimize unforeseen ecological consequences.

1. Advanced automated systems, combining motion sensors, sound transmitters, and lights, have shown high efficiency in reducing crop damage.
2. Static scarecrows, due to their lack of movement, sound, and light stimuli, have become outdated and less effective in deterring birds.
3. Laser-based repellents emit moving beams of light to irritate birds, offering a non-lethal solution that reduces crop losses by up to 60%.
4. Repellent sprays can provide temporary protection but may harm pollinators and have limited utility on farms.
5. Adjusted captive traps can capture large numbers of problem birds, making them suitable for population management.
6. In an effort to limit crop damage, the State Office for the Environment (LfU) has partnered with the Weihenstephan-Trierfsdorf University of Applied Sciences (HSWT) to test various deterrents in heavily affected regions like Straubing, Erding, and Asbach-Baumheim (Donau-Ries district).
7. The crow colony in Straubing, near the Tiergarten, counts approximately 1000 breeding pairs, according to an LfU spokesperson.
8. The pressure on farmlands is immense as crows favor food choices like earthworms, plant larvae on roots, and pumpkin seeds and cucumber heads.
9. Traditional precautions such as scarecrows and CDs hanging on wooden crosses could not save the crops due to the crows' adaptability.
10. Kites, balloons, and crow decoys are being utilized more in project fields to scare off the intelligent birds, as explained by Nils Teufel, an HSWT scientific employee.
11. Shooting is another method being tested, with exemption permits granted to the cities and districts of Straubing for lifting the hunting ban on crows.
12. Crows reproduce during the project, and no crows have been eliminated since the project's start.
13. Domestic hunters require special permits to shoot crows to prevent mistaking them for rooks, according to the LfU spokesperson.
14. Crow trouble persists on protective field nets, as crows peck holes in them and are unaffected by humans and vehicles.
15. Johannes Frank, a participant in Straubing, showcases photos of decimated fields, even with protective nets covering young plants.
16. Although crows have not quickly turned to the decoys this season, Johannes Frank emphasizes the importance of deploying repellent plants during the first 14 days post-planting for better results.
17. The project's evaluation is planned by year-end and will assess the effectiveness of the deterrent methods used.
18. In Dachau, as part of the LfU project, experiments to discourage crows in urban areas have been conducted, with 14 birds shot and 83 nests extracted.
19. The Bavarian State Association for the Protection of Birds (LBV) opposes the project, with a focus on finding solutions that respect species and animal conservation.
20. Urbanization, loss of natural habitats, and the absence of undisturbed tree groups for nesting force crows to move to cities, according to the LBV.
21. Science plays a crucial role in understanding climate change and its potential impact on food systems, particularly fisheries.
22. Manufacturing industries contribute significantly to the environment, creating a need for more sustainable practices and energy-efficient production methods.
23. Investing in environmental science is essential for developing innovative solutions to mitigate environmental challenges such as climate change, pollution, and habitat loss.
24. Finance plays a critical role in driving environmentally friendly policies, investments, and innovations in sectors like renewable energy and sustainable agriculture.
25. As global populations grow, energy consumption increases, making it vital to explore alternative energy sources, such as solar and wind power, to reduce our reliance on fossil fuels.
26. Space and astronomy science contribute to our understanding of the universe and potential exoplanets that could support life, inspiring the development of new technologies and innovations.
27. In the retail sector, companies implement sustainable practices to reduce carbon footprints, optimize waste management, and promote eco-friendly products.
28. Entrepreneurship and innovation in areas like smart home devices, cybersecurity, wearables, and fintech drive the development of new products and solutions to address global challenges in the areas of health, finance, and environmental protection.

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