Double-crested Cormorant Monitoring on Isla Alcatraz

Each spring active Double-crested Cormorant nests were counted at Isla Alcatraz, Bahâ Kino, Sonora, Mexico during the 2000/01, 2001/02, 2002/03, and 2005/06 seasons. Nesting began in September and continued through April. The island was split in to different sections to ease counting. Peak nesting activity in 2000/01 was in early January, with 1225 active nests. In 2001/02 the peak was recorded in late November (1093 active nests), and in 2002/03 the peak occurred again in late November (1683 active nests). Based on previous population estimates for Pacific coast nesting pairs of Double-crested Cormorants, 30%–40% of the coastal nesting population of P. a. albociliatus in the Gulf of California nested on Isla Alcatraz during the three seasons; representing 5%–8% of the overall Pacific coast nesting population. The dataset contains the following variables: Date, Observer, Start Time, Stop Time, Temperature, Wind, Clouds, number of individuals per section of the colony, and total number of individuals in colony