At this season of the year the river is pushed backward by the tide a matter of ten miles or more above Sacramento City: on the San Joaquin it is felt as far as Crow's Landing. At Antioch it begins to be saltish, and down through Suisun and Carquinez the river-water fights its way as far as San Pablo before its identity is wholly lost. At flood-times it may be traced, a yellowish, turgid streak, as far as Alcatraz. This is the islet of the albatross which lies south of the tide race, as Tiburon is on the north, fragments all of them of that salt-rimed ledge outside the gate where hoarse sea-lions play, and brother to the castellated cloud far along on the sea's horizon, the very capital of the kingdom of the Little Duck. [Illustration: MILL VALLEY, AND BACKWATER OF SAN FRANCISCO BAY] The Faralone Light is the last dropped astern by the Island steamships sagging south to the equator; it is also the sea-birds' city of refuge. This is the great murre rookery of the west coast, and formerly thousands of dozens of eggs were regularly taken from the Faralones to the San Francisco market; but since the islands became a Government station the murres have no enemy but the pirates of the air. In clefts and ledges close against the wall-sided cliffs they defend their shallow nests against the sheering gulls, or, hard beset, will push their single, new-hatched nestling into the friendlier sea, darting to break its fall with incredible swiftness, for a swimming gait is one of the things that come out of the shell with the native-born at the Faralones. On the same shelving rocks puffins rear their ratty young in burrows or under sheltering boulders, and the ashy petrel, the "little Peter" of the sea, walking by night before the storm, comes ashore here to hide his seldom nest. On the south Faralone the fierce cormorant builds her house of painted weed, which often the gulls steal from her as fast as she brings it ashore, for the gulls are the grafters of the sea-birds' city. This particular variety, known as the western gull, neither fishes for himself nor forages for building material. He feeds on the eggs and nestlings of his neighbours, or waits to snatch the day's catch from the beak that brought it up from the sea. He has the virtue of all predatory classes, an exemplary domesticity. His nest is soft and clean, his nestlings handsome. The western gull is often found marauding far up the estuary of Sacramento, but it is his congener, the herring gull, who follows the long white wake the ferries make ploughing the windy bay; or, distinguished among the silent shore birds for multitude and clamour, scavenges its reedy borders.