Land-bird density on Espíritu Santo Island, lower Gulf of California, Mexico, was determined bimonthly from November 1998 to October 1999. Bird density was quantified in 4 habitats on the island using the line transect sampling method. Fiftyeight species were recorded, of which 44 were detected in the transects and the other 14 in adjacent sites. The highest bird densities were observed in March and June, coincident with the lowest rainfall months in the neighboring peninsular mainland. Average density (birds/ha) was highest in alluvial fans (18.14) and lowest in mesas (8.08). Migratory bird density on the island was relatively low and commonly less than 10% of the observed total density. The average land-bird density on the island (13.29/ha) was greater than that previously recorded.