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PACIFIC SCIENCE, VoL XIII, July 1959 
toward us. Such behavior contrasted strongly 
with that of males not exhibiting sexual 
behavior. 
Captive Animals 
Mr. Spencer Tinker {^in lit) contributed ob- 
servations on three monk seals, each of which 
he has kept in captivity at the Waikiki Aquar- 
ium for more than a year. Two seals, a male 
and female, were subadult and no breeding 
activity was observed. 
The seals were playful and showed consid- 
erable tameness but would not allow them- 
selves to be touched. While cleaning the pool, 
attendants were occasionally "nipped in the 
pants and on the leg” by the seals as they 
played nearby. The animals often played "for 
hours in mock battles and gentle wrestling.” 
They also played with objects such as bits of 
rope, rubber balls, and pieces of wood which 
spectators dropped into their pool. 
Their response to the presence of other ani- 
mals in the pool varied considerably. They 
got along well with harbor seals {Phoca vita- 
Una). The two species never fought. How- 
ever, at feeding time, the harbor seals hung 
back and gave way to the monk seals. Sea 
turtles {Chelonia my das) in the pool were per- 
sistently annoyed by the monk seals which 
would grasp the turtles’ hind flippers in their 
teeth. The turtles were removed when their 
hind flippers became shredded by the seals’ 
teeth, A hawks-bill turtle (Eretmochelys im- 
hricata), however, would pinch the seals on 
the belly and the seals, in general, avoided it. 
During an encounter, this turtle was bitten 
by a seal and blinded. A 5-foot bottom-living 
species of shark was relentlessly pursued by 
the seals. Eventually, the shark was exhausted 
and a seal dragged it backwards through the 
water by the tail. When a small pilot whale 
{Globicephala) was placed in the pool, the 
seals were terrified, but in a few days "they 
were around it, smelling and rubbing it with 
their noses.” In general, the seals appeared 
more nocturnal than diurnal. They spent most 
of the night in the water and would rest for 
many hours on an island in the pool during 
the day. 
BIRTH AND DEVELOPMENT OF YOUNG 
Pupping Season 
Pups are born from about the first of the 
year until at least the end of June. Most are 
apparently born from mid-March through 
May. 
In 1957, the first pup was seen from the air 
on a Laysan Island beach on January 7. The 
earliest authentic birth date we can find for 
Midway Atoll is March 22, 1956. At 0900 on 
that date, J. E. Graves {in lit) of Honolulu 
saw a newly born pup on the west tip of 
Eastern Island. "The pup was still wet and 
the fetal membranes were attached. It had 
probably been born less than an hour.” 
Bailey (1952) recorded a newly born pup on 
Pearl and Hermes Reef in late December, 
1912, and that on March 15, 1913, 20 females 
with pups were seen at Pearl and Hermes Reef. 
During the spring of 1957, five pups were 
born at Midway. The first, a premature 9- 
pound female, was found dead February 27 
on the beach at Eastern Island. Birth dates at 
Midway in 1957: 
February 20 (est.) 1 female 
March 24 2 males 
April 2 2 males 
On June 5, 1957, 19 pups were examined 
on the beaches of Green Island, Kure Atoll. 
One had been born the morning of our ar- 
rival. The weights of the others were estimated 
and their approximate birth dates, all in 1957, 
calculated by reference to known growth and 
molt rates: 
NUMBER 
BORN 
April 10-20 1 
April 21-30 . 7 
May 1-10 3 
May 11-20. 3 
May 21-30. 2 
May31-June5. 3 
