Il6 BROOKLYN INSTITUTE MUSEUM. SCIENCE BULLETIN 2. 5- 
following the last complete glaciation, very little territor}^ suitable for 
breeding pnrjio.ses was expo.sed. Whatever bare earth existed mu.st have 
been found along the ridges which .separated the ice-filled valleys. During 
such a jieriod, before the parent stem of the Pygoscelis group had been 
differentiated into several species, the.se .small penguins may have 
developed the trait which .still leads them to .seek lofty jilaces for their 
nests. The fact that South Georgia was formerly the home of a far more 
abundant fauna than at pre.sent would have tended to fix the “mountain- 
eering” instinct, for animals obtaining their sustenance only in the .sea 
would have a tendency to increa.se more rapidh" than the proportionate 
area of the beaches, and through sheer overflow of population many birds 
would be forced to content themselves with the le.ss acce.s.sible ground, 
leaving the shores to great herds of .summering .seals,* and the adjacent 
nesting-.sites to powerful rivals such as the Aptenodytes penguins. Then 
there is the factor of floods, whether cairsed by exce.ssive thaws or by 
excejitional tides imiielled b\' storms. At the Bay of Isles I found not 
only mas.ses of kelp but also the heavy .skull of a killer whale ( Orca) far 
back on the great moraine-beach where it .seemed almost incredible that 
the sea could have carried them. Becan.se of the elevation of their nests 
the Pygoscelis ])engnins are more .secure again.st floods than the Aptenodytes. 
Possibh" this accounts in part for the greater numerical strength of the 
former, for although Pygoscelis lays one more egg than its larger relative, 
the king penguin’s single offspring .seldom if ever becomes the prey of the 
skua, which plays such havoc among the rookeries of the johnnies. 
The h}'pothe.si.s which I have advanced would be as applicable to any 
other austral region as to .South Georgia, for the same ph}-siographic and 
biological conditions have doubtless obtained throughout a wide circum- 
polar belt. 
The faith which the johnny penguins hold in the protectiveness of 
high land is .strangely shown by their habit of running aicav from the 
water whenever danger threatens. Their enemy, the .sea leo^iard, has 
fixed within them an instinct which urges them to .seek .safety only on 
term pinna. Con.sequenth' they do not govern their acts according to 
their perceptions. Time and again I have .seen a group of them .standing 
at the water’s edge when a fox terrier, brought ashore from the Daisy, 
.started toward them at a run. If the ])enguins deigned to show any fear 
* At .South C.eorgia I liave .seen .sea ele])hants [yfi) oini^a Ironitia) drag themselves .so far from 
the water that they became a blind menace to johnny penguin nests on low ground at the ont.skirts 
of a rookery. 
