From the "Birds, Bees, and Aquatic Life Threatened by Gross Underestimate of Toxicity of World's Most Widely Used Pesticide" press release from the American Bird Conservancy:
ABC commissioned world renowned environmental toxicologist Pierre Mineau to conduct the research. The 100-page report, “The Impact of the Nation's Most Widely Used Insecticides on Birds,” reviews 200 studies on neonicotinoids including industry research obtained through the US Freedom of Information Act.  The report evaluates the toxicological risk to birds and aquatic systems and includes extensive comparisons with the older pesticides that the neonicotinoids have replaced. The assessment concludes that the neonicotinoids are lethal to birds and to the aquatic systems on which they depend.

“A single corn kernel coated with a neonicotinoid can kill a songbird,” Palmer said. “Even a tiny grain of wheat or canola treated with the oldest neonicotinoid — called imidacloprid — can fatally poison a bird. And as little as 1/10th of a neonicotinoid-coated corn seed per day during egg-laying season is all that is needed to affect reproduction."

See the press release. Note: page contains link to PDF version of the report.

See the report [PDF].