Nesting of Yellow-footed Gulls on Isla del Carmen, Baja California Sur, Mexico

From February to June 1996, we observed breeding numbers, chronology nest characteristics, and productivity of Yellow-footed Gulls (Larus livens) on and near Isla del Carmen, Baja California Sur, Mexico. Of 124 active nests on Isla del Carmen, 75.8% were single or in groups of less than or equal to ten nests. Most nests observed were 1.5-10 m above high tide line on top of bare rock. Distance to the nearest neighbors' nest varied from < one m to 50 m ((x) over bar = 12.3, 9.5 SD, n = 19). Egg-laying started in late March-early April at different colonies; hatching was completed by mid-May. Productivity at hatching was comparable to published estimates for the species. We found a discrepancy between our gull counts and another reported population estimate for the island, thus confusing population estimation used for conservation planning.