Greene, H. 1987 16 August Tilden Regional Park, Contra Costa Co., California I arrived at the miniature steam train ride ~1400h at the request of park naturalist Rachel MacDonald. The people who run the little train had complained of a group of rattlesnakes so close to the tracks that they feared a snakebite and lawsuit. The men (led by Eric Thompson) told me that they are not opposed to rattlers, but felt that these were a danger. Three days ago they saw two spacing upright with each other, presumably male-male combat, and earlier today two adults. We rode the train through oak savanna and chaparral stopping at a rock pile beside the track. It was 3-4 m in diameter, <1m high except for one large boulder, and encompassed a small group of shrubs. There was a pair of Crotalus viridis copulating in the shade of the shrub when I arrived, and the ♀ rattled furiously when I hoisted them into a bucket (next day, not in copula, the male was more aggressive). We moved all the rocks we could, but found no other snakes. The rocks were more than 1 m from any passenger at any