5 
Sooty Shearwater $ Obs. = 2 
Sooty or Slender-billed Shearwater # Obs. = 3 
5 
0 10 
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 cluster¬ 
ing in the south. 
Leach’s Storm Petrel 
Oceanodroma leucorhoa 
# Obs. 
= 53 
333 
.034 
.033 
.029 
5 8 6 
.059 
.062 
.059 
5 6 14 
# Obs. in each section 
. 047 .072 . Il4 
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 
(0. 1. 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 
