-3- Collecting was performed whenever possible. Use of the small skiff whenever weather conditions permitted was made during several long ocean- ograpic stations. Oil slicks were usually spread during these times in attempts to attract storm petrels as well as other species. Throughout the cruise 149 birds were collected; the majority of these were storm petrels of two species. Preparation of specimens at night occupied so much time that nocturnal observations were not held. Spot checks were made to ensure that species different from those recorded during diurnal observations were not being missed, but these times were not recorded. Because of the time needed to write the present report, only a few hours daily of observation time were conducted during the return coastal run between Manzanillo and San Diego. Considerable observations have been conducted through this area and in fact reliable density estimates cannot be made whenever the ship is close to land. The present cruise has been divided into sections according to the water types listed below. In most cases these water masses do not appear to be distinct boundaries for bird species. However, since we are dealing with pelagic species, subdivision by natural oceanic zones seems more ap- propriate than arbitrarily chosen lines. Delineation of the various cur- currents was made from analyzation of oceanographic data. AREA A. COASTAL WATERS Time span: 20-27 Feb. and 29 March-5 April. All coastal waters to 150 miles from shore from San Diego to Manzanillo and return are included in this area. Several different water types are undoubtedly included here as suggested by the distribution of certain pel- agic bird species, but the usual land based species dominate throughout. Large flocks of mixed Sooty Terns and Townsend's Shearwaters were encoun- tered at the mouth of the Gulf of California. AREA B. NORTH EQUATORIAL CURRENT WATERS Time span: 28 Feb.-1 March and 24-28 March. Boundary limits: 7° N latitude - 13°-30' N latitude. Moderately high numbers of large shearwaters, large Pterodroma, Leach type storm petrels and Sooty Terns were encountered in this area. Some in- fluence of Clipperton Island based species also affects this region. AREA C. NORTH EQUATORIAL COUNTER-CURRENT WATERS Time span: 2-3 March. Boundary limits: 4°N-7°N latitude along 105°longitude and 5°-30' N to 7°N along 112°W longitude.