Blackbird Population Management to Protect Sunflower: A History

Sunflower (Helianthus annuus) growers in North Dakota and South Dakota harvested 593,522 ha in 2012, valued at $US600 million. Blackbirds, numbering about 75 million, annually damage 2 to 3% of the crop. Damage tends to be clumped around cattail (Typha spp.) dominated wetlands with standing water. In an attempt to reduce sunflower damage, three general population management strategies have been tested over the past three decades. One potential strategy was to reduce blackbird numbers during winter in the southern U.S. A second strategy was to use an avicide at spring roost sites in eastern South Dakota. A third approach was to reduce local blackbird populations that were doing or about to damage ripening sunflower. All three schemes largely relied on the use of DRC-1339 (3-chloro-4-methylaniline hydrochloride) and related compounds and all failed because of logistics, cost-effectiveness, environmental risks and societal concerns. In this paper, I chronicle significant research efforts to implement these strategies.