Overall Tree Swallows populations declined by 49% between 1966 and 2014, according
to the North American Breeding Bird Survey. A PinP photo.
Bird biodiversity is declining at a marked rate. Bird populations in the United States have decreased by 29% since 1970, which has been attributed to various factors including the increased use of pesticides in agricultural production. Nicotine-based pesticides — known as neonicotinoids — have been used increasingly in the United States over recent decades. Previous research has shown that neonicotinoids are potentially toxic to birds and other non-target species. However, the impact of these pesticides on bird diversity in the United States is unclear.