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 Mar.,1917 LIST OF BIRDS BREIDING IN SAN FRANCISCO COUNTY $$ ty. Although the county is small it presents some points of marked ornitholo- gical interest. The Farallon Islands furnish a nesting place for thousands of birds from the open sea, and in the nesting season these rocky islets present one of the most striking ornithological phenomena to be seen in any of the states of our Union. The mainland portion of the county is not without interest to the thoughtful student of birds. There is probably no area of similar size in the State vhich has so much to teach us concerning the effects of human environ- ment on bird life. Vast changes have taken place in this little area during the last sixty years. During that time a city of a half-milli)n people has grown up on the tip of the peninsula south of the Golden Gate. Salt marshes have been filled, and the shore line in many places pushed far out'into the bay. Hills have been leveled and creeks filled. Bushy hillsides and sand-dune tracts .have been built Fig. 20. STOW LAKE,  GOL)Er GATE PARK, SAr Fr. tlClSCO. up into residence districts. Such changes must of necessity affect the avifauna of a region. Indeed, at first thought, one might vonder vhether many species of birds vould remain after such sveeping changes. That many species have not only survived but have actually nereased in numbers, and that several nev species have come to make their homes in the county, is the conclusion toward which the present avifaunal condition of the county seems to point. In undertaking this study of the nesting birds of San Francisco County we have had two objects in view. Our first object has been to furnish to those interested in our birds a reliable list of species making this county their home; for a bird's home is where it builds its nest. Our second object has been to fur- nish, if possible, some reliable data concerning that far raster problem, namely, the effect of the occupation of a territory by the vhite race upon the native birds. In order to furnish data of the last named kind ve sought to learn as