Photo Credit: Joseph Watson

Organic certification requires farmers to support important biodiversity such as birds and bees. While a lot of research has shown that more plant diversity both on and off the farm can increase wildlife, not all biodiversity is welcomed. Some wildlife can cause problems as pests, and this includes some types of birds. Birds can be very helpful by providing natural pest control when they eat insects that would otherwise eat crops. But, birds can be harmful when they eat the crops themselves or contaminate crops by defecating on them. A new study published in the Journal of Applied Ecology shows that having birds on a farm can be both good and bad, but the good offsets the bad, especially when the farm is surrounded by natural habitat. To measure how plant diversity influenced the types of birds found on the farm, the researchers mapped out vegetation both on and around the farm, and then counted and identified the birds that visited each farm. To quantify how much birds were harming versus helping the farm, they measured bird damage to strawberry crops. In a separate experiment, they measured natural pest control provided by birds.

The study found that within the organic system, more plant diversity on the farm increased the overall number of birds (including both good and bad birds). Also, farms surrounded by more natural habitat had more good birds. However, the researchers also found that having more birds overall on the farm was not as detrimental as some would think. In fact, the amount of damage that birds caused by eating strawberries (about 3%) was the same amount that they saved by eating insects that eat strawberries (about 3%). This study suggests that more crop and non-crop vegetation can be effective in increasing bird biodiversity on farms. And, even if the bad birds come with the good, the overall benefit of supporting more biodiversity prevails.