Hawaiian Monk Seal — Kenyon and Rice 
229 
Fig. 5. Trails and wallows as seen from the air aid in locating seals partially hidden among sand dunes and 
Scaevola clumps. Characteristically, seals are grouped near points of sand as shown here. Laysan Island, January 
7, 1957 (KWK 57-1-17). 
counts made on 49 days during the regular 
boat runs to and from Eastern Island. 
The number of seals counted on land de- 
pended on the total area observed. The largest 
counts were made from aircraft, intermediate 
counts from land, and the smallest counts 
from the boat. The relative number of seals 
counted by the three methods indicated that 
the sample area observed from the boat was 
a reliable index of the abundance of seals on 
land in Midway Atoll. The monthly mean of 
boat counts is shown by a solid line in Figure 
7 to indicate the general trend of seasonal 
abundance on land. 
We suggest two possible explanations for 
the variation: (1) the seals spend more time 
in the water during summer because of high 
air temperatures, and (2) the seals move out 
onto the unprotected reef during the calm 
summer season. We have some evidence to 
support the latter hypothesis. In five flights 
over 'Tive-mile Reef,” from December 9 to 
February 12, we observed no seals hauled out 
on the reef. On March 27 we visited the reef 
in a small boat and counted 11 seals. On May 
13 we cruised outside the reef in a tugboat 
and saw 13 seals lying on the exposed reef 
rock. Probably each of the above factors is 
partly responsible for the disappearance in 
summer of seals from their winter hauling 
grounds. 
The yearling seals present an interesting 
