5 Sooty Shearwater Sooty or Slender-billed Shearwater # Obs. = 2 # Obs. = 3/5 0 1 0 0 0 1 0 2 1 # seen in each section Evidently the fall migration is a rather abrupt peak. Grid numbers have dropped by a factor of 20 in two weeks. I would set the dates of maximum exodus at September 6-20. Five birds barely constitute a valid distribution pattern, but what there is suggests an unsurprising clustering in the south. Leach's Storm Petrel Oceanodroma leucorhoa # Obs. = 53 3 3 3 5 8 6 5 6 14 # Obs. in each section .034 .033 .029 .059 .062 .059 .047 .072 .114 Birds/Linear Mile/Section The wave of birds that was passing through the center of the Grid area during the last survey (early October) has evidently continued south. That wave, unlike the postbreeding summering populations, was distinctly and highly directive. I feel that those birds were the nominate race (O. l. leucorhoa) from stations to the north as they appeared to be larger and virtually all were conspicuously white-rumped. I believe it is probably this general population that makes up the bulk of the Leach's that spread westward along the low latitudes in the central Pacific. The current density is by far the lowest yet recorded. The birds seen did not appear to be directional and I doubt that many migrant stragglers are still lingering in the Grid area. The birds struck me as being chiefly the smaller small-rump patched birds from more local breeding stations. I suggest that the slight concentration of birds in the south- east corner represents birds from the winter breeding populations of Isle Guadalupe. As the breeding cycle there finishes up I expect this density peak in the southeast to remain, while the overall density increases as postbreeders and young disperse. January and February 1967 data also indicate this pattern. Problems continue to arise concerning the identification, specific and subspecific, of the Storm Petrels encountered in the Grid. Using the ADP system it is, at times, difficult to describe a sighting, and no standard procedure has yet been adopted. My present thoughts on the Hydrobatids of the Grid are outlined roughly as follows: Fork-tailed Storm Petrel Oceanodroma furcata Little problem. The Grid area evidently delimits the usual southern