ECOLOGICAL CHARACTERISTICS OF MARIANA ISLANDS. 11 
during July and August the breezes are much lighter in force and veer irregularly 
from quarter to quarter. The strong southwest monsoon blows throughout 
September, and then the winds change back to the opposite northeast quarter, or 
at least to the eastern half of the compass. The northeast winds are “dry,” while 
the southwest winds carry an excessive amount of moisture during the mid-year 
period. As a detail, it may be noted that Guam is not large enough to cause the 
diurnal production of land breezes, nor are its mountains sufficiently high to affect 
the prevailing winds to a material degree. 
TABLE 1.—Directions of the winds at Guam, throughout an illustrative year, 1902 (from Safford). The figures 
give the numbers of days. 





Ms North- South- South North- | Vari- 
Month. North. ary East. aie South. ey West. etme Silas 
VETTE Ta oes eee 3 ae ayaa ee oe eayens 16.5 11.0 Zea 1-0 of a - Toure 
UC TSATAT Vi, Nee cee tatetctrs auete wis Aiea: «iy che wis 12.0 9.5 6.5 ae sf = 2 sous 
MRRR Te ee Tohou hector, sasae aleuciasys a O55 16.5 1S O55 0.5 0.5 ae a ee 
EESERANE. «ole SNE NS a elias ,Seebre oualigta ue 6 soe 20.0 8.0 1.5 oF i ae ie Peinne 
Beare Pc Pues (ttn hs eee aS 13.0 14.5 125 rs ie ae ms 2.0 
PERRO fey cta seta dalin eo icacs Paomreinns asa ddh 6.5 17.0 4.5 1.0 a ane 32 1.0 
LATE tes ee ee ae 13.0 55 6.5 4.0 1,0 id 8 1.0 
ENC a CEA A) 4 A en Oe Lee LO Z.9 5.0 6.5 3.0 355 1.0 6.5 
OCECPE DEY. cisterns shoe «atk eels os oe a5 aie SBicke 6.0 16.5 5.0 275 re 
(iE Pel aS Oe SO ee Oe ce ee ahaha 4.0 10.0 3.0 6.0 1.0 1.0 ia 6.0 
PNET DED 2 te statelo <apsre sus enetens 6 = 4.0 6,08 14.0 025 3.0 ao 0.5 2.0 
PME CEM DOR. 2h cee iaiscs la hae oes 2.0 8.0 21.0 Gok Ps Se + Bind 
SST AL ye). eens) bio w nl bocawons Os | 8.0 i170 125.0 32.0 28.0 2200 10.0 330 L359 


Under the influence of the trades, the surface water of the ocean sets to the 
westward at a rate, at times, of 2 knots. The current thus induced would bear 
floating objects to the open ocean areas devoid of proximate islands. When the 
southwest monsoon blows, from July to September, the drift is to the northeast, 
that is, from Guam in the direction of Rota, Tinian, and Saipan. Floating seeds 
and leaves might thus be carried to the shores of the latter islands in the path of the 
drift in question; but the Partulz of an island like Guam for the most part frequent 
the shaded places back from the strand, and they are not likely to be borne to the 
sea on leaves, seeds, or larger fruits like the coconut. It is much more significant 
that the animals can not tolerate submersion or repeated washing in salt water, 
even though they can retain their vitality in fresh water for a limited time. 
Typhoons are of infrequent occurrence, but are intense and cause great havoc. 
It is generally conceded that the devastating storms of this nature which sweep 
down upon the Philippine Islands usually develop in the Micronesian area in the 
neighborhood of Guam. They do not always gain their full strength before passing 
to the westward, but occasionally they do. The terrific winds of a typhoon are the 
result of an excessively low barometric center, which likewise causes an exceptional 
amount of precipitation, amounting in some instances to 9 inches in a single day. 
At such times, various fragments of trees and shrubs are blown to the sea, or are 
swept by the deluge of rain into the swollen streams which discharge into the ocean, 
thus to come under the influence of the currents of the time and season. While 
it is conceivable that Partule might be carried to sea upon the detached vegetation, 
