Factors affecting intentional bird poisoning on bean farms in Taiwan: seeding methods and the presence of adjoining duck farms matter

Abstract

Intentional poisoning is a common practice to reduce bird damage to agricultural crops. Understanding the extent, distribution, and influencing factors of such incidents is key to reducing poisoning of farmland birds and scavengers which are threatened via secondary poisoning. We recruited volunteers to look for dead birds in red bean (Vigna angularis) farms during the seeding period in autumn 2016. A total of 5,441 fields were surveyed, and 51 bird poisoning incidents were identified. We recorded 1,995 dead birds during the survey (39.1 ± 29.7 per incident ± SD), mostly seed-eating birds. We tested two possible factors influencing the practice of intentional poisoning: seeding methods and whether the red bean farm was adjacent to duck farms. Among three seeding methods, broadcast seeding does not cover the seeds with soils and resulted in a significantly higher proportion of bird poisoning incidents when compared to the whole study area. However, when red bean farms were adjacent to the duck farms, there were no differences in the percentage of poisoning incidents among seeding methods but the number of dead birds was two times higher compared to incidents that were not adjacent to the duck farms. We suspect that birds congregating at duck farms resulted in neighboring farmers taking anti-bird measures, regardless of seeding methods. We map bird poisoning hot spots and provide evidence that changing seeding method and limiting the number of wild birds congregating near duck farms would help reduce bird damage and intentional bird poisoning on red bean farms. Finally, we demonstrated that citizen scientists can make a significant contribution to conservation.

Keywords

• black kite
• bird damage
• carbofuran
• ecological trap
• poultry farming
• secondary poisoning