As an introduced species, European starlings are not protected under the Migratory Bird Treaty Act. Starlings are considered a nuisance species in North America. The birds, which travel in enormous flocks, often pose dangers to air travel, disrupt cattle operations, chase off native birds, and roost on city blocks. They leave behind corrosive droppings and hundreds of millions of dollars of damage every year. In 2008, U.S. government agents poisoned, shot and trapped 1.7 million starlings, more than any other nuisance species.