Objectives:

1- To determine nesting sites at Carmen Island from February to June, 1996.

2- To detect and register the bird´s reaction to humans.

3- To identify the most visited areas by tourists at Carmen Island by means of direct observations and local informants.

From February to June, 1996, information on reproduction, egg and nests failure, vegetation type, location and area characteristics were obtained for the nesting sites of the yellow footed gull (Larus livens) at Carmen Island. Also, information about interactions between gulls and human activities and with the introduced bighorn sheep (Ovis canadensis weemsi) was obtained.

From April to June the number of eggs and chicks at Punta Perico was determined, as well as the plant species present, distance to the sea and nest orientation. In some cases, observations were made on the gull’s feeding habits and predators. Nesting areas were found from an outboard motor boat.

124 active nests were located at Carmen Island, of which 24.2% were observed in colonies of more than 10 nests, and 75% were alone or in groups of less than 10. Most of the nests were located between 1.5 and 40 meters above the sea level on rocks and 3 to 17 meters from the sea line. Hatchlings were born from late March to early April.
Possible eggs and hactlings predators include crabs (Grapsidae), ravens (Corvus corax) and domestic cats (Felis domesticus).

No human activities were recorded at nesting sites, and no interactions between bighorn sheep and gull were observed. Other sea birds present, but that not nest at Carmen Island include the brown pelican (Pelecanus occidentalis), frigatebird (Fregata magnifiscens), blue-footed booby (Sula nebouxii), brown booby (S. leucogaster) and Heermann’s gull (Larus heermanni).