Apr. 1. Heard first Pileated Warblers in Sunny Gulch. Cold, Clear. 2. Warmer. Birds all singing. Purple Finches, Vesper Horn, Titmouse, Thrasher, Song Sparrows, Hermit Thrush, Fox Sparrow (whispers), Golden-crowned Sparrow, Lutescent Warbler, Meadow Lark's. Cold at night. 3. Cold - rain in afternoon. Heard Warbling Vires for first time this spring. Several Pileated Warblers heard. Tom- sends Warblers singing 4. Rain - cold. Clear, cold in afternoon. Rain and hail again at night. 5. Very cold morning - showers. Many Pileated Warblers heard both here and in Sunny Gulch. Townsend Warblers feeding and singing in the oaks near kitchen windows. New leaves on oaks fully out. Hazel quite green. 6. Drove to S.F. then down Skyland Blvd. to San Mateo. Views gorgeous - white clouds broken, blue sky, water very blue and sparkling. Across the bay the Mt. Hamilton range was white with snow - looked like the Sierras. No snow on Diablo or Tamalpais. 7. Air still cold but sun warm away from breeze. 9. Thick white frost in morning, melting immediately when sun reached it. Walked up Strawberry Canyon with bird class. A late spring - Trillium still blooming. Only spring birds in were Allen Hummer (not all,) Lutescent and Pileated Warbler and 1 Chipping Sparrow - Botanical Gardens. Warbling Vires? More unusual birds found: Hutton Vireo (3) and Willow Goldfinch. No House Wrens or W. Flycatchers yet. 18. Morning frost again. 1 Small group of Junct. Sparrows in creek bed.