About this time there was a swish of wings, and a sharp-shinned hawk (_Accipiter velow_) darted like a streak among the woodpeckers. For an instant it seemed that one of them was doomed, but by a small margin it managed to escape, and in an instant they had all darted to cover among the green boughs of surrounding trees. All was quiet for a few brief seconds, when the woodpeckers returned to the attack, except one which perched on the topmost bough of a near-by tree, as guard or lookout, watching for the hawk. The other seven took up the fight with the squirrel. In a few minutes the hawk again appeared on the scene, the guard gave a shrill call of warning, and all the woodpeckers were under cover before their enemy could reach them. The hawk, then, finding the birds on their guard, left and did not return. The terrier soon abandoned the tree, and the squirrel hurried down and scampered away; the woodpeckers quickly quieted down and went peacefully about their home affairs. I believe that the birds recognized in the squirrel a danger to their eggs or young. BALANOSPHYRA FORMICIVORA MARTIRENSIS Grinnell and Swarth SAN PEDRO WOODPECKER HABITS The acorn-storing woodpecker of the Sierra San Pedro Martir, northwestern Baja California, has been separated and described by Grinnell and Swarth (1926) under the above name, to which they have added the long common name “San Pedro Martir acorn-storing woodpecker.” Its distinguishing characters are given as follows: Most nearly like _B. f. bairdi_. Distinguished from that species primarily by shorter wing, and by slightly shorter and notably weaker, more slender bill; also by average differences in head markings as set forth below. * * * The relatively feeble bill of this bird, as compared with that of the upper California _bairdi_, is the most conspicuous character of this subspecies. In bill structure it is closely similar to _B. f. aculeata_, of Arizona.