FIELD NOTES Location: Alcatraz Island, S.F. Bay, CA. DATE: April 19, 1985 angle downwards. Some pairs were seen to "choke", displaying their nesting site. One dead adult gull found, well progressed in decomposing. Other birds seen on Alcatraz: White-crowned Sparrow (several singing) Song Sparrow " " Black-crowned Night Herons - many (~30), mostly adults sitting in various "colony" trees. Anna's Hummingbird - male in dive-bomb courtship. Heerman's Gull - (1). Flew about the laundry. Landed a top its roof and was subsequently chased by the Western Gulls sitting there. Judd Howell mentioned that when he studied Heerman's Gulls resting here, they won encounters with Western Gulls as the island was less disturbed. When human disturbance increased, Western's began to win encounters more frequently. Oystercatchers (8) - down on Baker Beach at West side of island.