Blackbird damage to rice has become a major economic problem for growers in Morelos, Mexico. Blackbirds, specifically the red-winged blackbird (Agelaius phoeniceus), brown-headed cowbird (Molothrus ater), and the red-eyed cowbird (M. aeneus) caused approximately 3.68% damage per hectare during spring-summer 2000. Other species such as the blue grosbeak (Passerina caerulea) and the blue-black grassquit (Volatinia jacarina) damage rice crops too, but mostly in the field borders near secondary vegetation or other crops like sugar cane or maize.