220 
PUPPING AREAS: All of the newborn pups 
we saw at Midway and on other atolls were 
on permanent islands or islets above high 
tide, or on sandspits only a few yards from 
permanent dry land. We did not see them on 
isolated, temporary sandspits which could be 
covered by high tides or washed away by 
storms, although these are regularly used as 
hauling grounds by adults. 
ABUNDANCE 
Two methods were used to estimate the 
size of the Hawaiian monk seal population: 
aerial surveys and ground counts. 
We conducted aerial surveys of all the 
atolls on which seals are known to breed, 
with the exception of French Frigate Shoals. 
Counts for the latter atoll were made by Paul 
L. Breese, director of the Honolulu Zoo, and 
by POFI biologists. Our aerial counts were 
made from Navy UF-1 Grumman Albatross 
amphibians flying at a speed of about 120 
knots and altitudes between 100 to 500 feet. 
In most cases, each of us made an independent 
count using a mechanical hand-tally. Usually 
we made at least two successive counts dur- 
ing each flight. The counts were sometimies 
checked against photographs taken simul- 
taneously with a Fairchild F-56 camera. Dur- 
ing any one flight, the differences between 
successive counts by the same observer, be- 
tween different observers, and between the 
observers and the aerial photographs, were 
insignificant. Few of the seals on land were 
missed. Occasionally, a seal resting under the 
edge of a Scaevola thicket was difficult to see. 
Large green turtles {Che Ionia my das) basking 
on the beaches were momentarily confused 
with seals but caused little difficulty in 
making counts. 
Ground counts were made on Midway and 
Kure atolls by walking entirely around the 
beaches of the larger islands and by landing 
on all of the sandspits and small islets. 
The number of seals on land varies with 
the time of day and the season (Table 7 and 
Fig. 7). The best time for counting seems to 
PACIFIC SCIENCE, Vol. XIII, July 1959 
be in afternoon during winter, when the most 
seals are on land. However, we had no way of 
knowing what fraction of the population was 
absent. Some individuals certainly were ab- 
sent, as indicated by algae in the hair, men- 
tioned elsewhere. 
The population figures, by atolls, are pre- 
sented in Table 4. The total prior to the pup- 
ing season is based on the highest counts of 
all seals during the winter of 1956-57, or else 
the highest counts of seals of age one year 
and older made during the spring of 1957. 
The total number of pups is based on the 
highest single count of pups, or on com- 
bined counts when it was evident, from age 
or location of pups, that different pups were 
counted. The total after the birth of the pups 
is the sum of the largest count of adults plus 
the total count of pups, and thus does not 
necessarily represent a single count. Because 
of the distances involved, we do not believe 
that the same seals were seen twice in widely 
separated atolls. Following is a brief descrip- 
tion of the six atolls on which monk seals 
breed, and a listing of the dates on which we 
made counts of the seals. 
Kure Atoll 
The reef encloses a circular lagoon 6 miles 
across. Inside the southeast reef is Green 
Island, 1 mile long by Vi mile wide, largely 
covered with a dense growth of Scaevola. Sev- 
eral variable sandspits extend to the westward 
of the island for about 2 miles. Flights were 
made over Kure on December 9 (1100-1130), 
December 21 (0900-0930), February 12 (1430- 
1520), and May 14 (1355-1435). A ground 
count was made on June 5. 
Midway Atoll 
The lagoon at Midway is about 6 miles in 
diameter. Inside the southern part of the reef 
are two large islands. Sand Island, 2 miles long 
and 1 mile wide, is the site of a U. S. Naval 
Station. Eastern Island, 1V4 miles long by 5^ 
mile wide, is uninhabited except for a single 
Navy unit. Between the two islands are sev- 
