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forest and stream 
April, 1919 
MIGRATION SOUTH OF THE EQUATOR 
SOMETHING ABOUT THE LITTLE KNOWN SUBJECT OF 
BIRD MOVEMENTS IN THE SOUTHERN HEMISPHEREj 
M r. frank KABAN, of the United 
States Marine Corps, stationed at 
Mare Island, California, has writ- 
ten the natural history editor as fol- 
lows: 
“Why do we never hear of a southern 
migration, that is a migration of the 
birds of the southern hemisphere toward 
the south, just as our birds migrate to 
the north, in the spring? 
“It seems reasonable to expect the 
birds south of the equator to do that, 
but I have never heard or read anything 
to that effect.” 
This question should be understood to 
apply to land birds only. In one sense it 
would be quite fair to answer it by say- 
ing that we hear so little about bird 
migration in the southern hemisphere 
principally because the subject has never 
been adequately studied in that half of 
the world. Since the dawn of history, 
the great centers of population and civil- 
ization have been in the temperate re- 
gions of the northern continents, and 
the return of the swallow in the spring 
was as familiar to the Greek poet, An- 
acreon, as it is to us today. Likewise 
the author of the book of Job speaks of 
the hawk that stretches her wings to- 
ward the south, a phenomenon that we, 
too, note recurrently in autumn. But 
the habitable lands south of the equator, 
which means Australia and New Zea- 
land, the greater part of South America, 
and less than half of Africa, have be- 
queathed us no old literature filled with 
such a tradition of bird migration, and, 
during the relatively brief period in 
which these areas have been settled by 
northem man, there has scarcely been 
an opportunity for noting and recording 
the actual facts regarding southern birds 
that make seasonal journeys toward and 
away from the equator. In this connec- 
tion it should not be forgotten that in 
absolute numbers, as well as in propor- 
tion to the total population, there are 
even now vastly fewer naturalists in the 
southern countries of the globe than 
there are in the United States, Canada, 
and western Europe. 
Nevertheless, after we have made due 
allowance for the conditions just men- 
tioned the truth remains that, at least 
as regards land birds, migration in the 
southern hemisphere has attained no 
such dimensions, either in the number of 
migrant species or the distances trav- 
ersed, as we find in all parts of the 
north temperate and boreal world. The 
most obvious reason for this is to be 
By ROBERT CUSHMAN MURPHY 
HE Natural History Depart- 
ment has been for nearly half 
a century a clearing-house for in- 
formation of interest to all. Our 
readers are invited to send any 
questions that come under the head 
of this department to Robert Cush- 
man Murphy, in care of Forest 
AND Stream. Mr, Murphy, who is 
Curator of the Department of Na- 
tural Science in the Brooklyn 
Museum, will answer through these 
columns . — [Editors.] 
sought in the distribution of continental 
masses. We all realize that the north- 
ern hemisphere contains the greater part 
of the earth’s dry land, but only by look- 
ing at a geographic globe from a north 
polar point of view can we gain an 
adequate conception of the manner in 
which the great continents of Eurasia 
and North America are crowded around 
the northem axis of the world. Look- 
ing southward in all directions toward 
the equator, we find that even China, In- 
dia, and Arabia lie well to the north of 
the line, while two-thirds of Africa, and 
a considerable section of South America, 
are also included within the northern 
hemisphere. Beyond the equator, at the 
periphery of the terrestrial world, we 
find only the minor continent of Austra- 
lia, and the narrowing wedges of South 
America and Africa extending into a 
vast ocean. How diiferent, too, are the 
relations of these southern lands to each 
other and to the austral poles! Cape 
Horn, the extreme tip of South America, 
lies in about 56 degrees south latitude, a 
position corresponding to that of Edin- 
burgh and Copenhagen in the northem 
hemisphere. Africa extends only about 
as far south of the equator as Los An- 
geles and the Strait of Gibraltar lies 
north of it while Tasmania and New 
Zealand carry the inhabited southern 
lands to parallels corresponding with 
those of Boston, southern Canada and 
Paris. 
Under such circumstances, the move- 
ments, and very population of land birds 
of the southern hemisphere must clearly 
he far more limited than those of the 
birds distributed throughout the snaci- 
ous north. In the words of Professor 
Alfred Newton, the distinguished Eng- 
lish student of ornithology, “if the re- 
lative proportion of land to water in the 
southern hemisphere were at all such as 
it is in the northern, we should no doubt 
find the birds of southern continents be- 
ginning to press upon the tropical and 
equatorial regions of the globe at the 
season when they were thronged with the 
emigrants from the north, and in such a 
case it would be only reasonable that 
the latter should be acted upon by the 
force of the former But, though 
we know almost nothing of the migration 
of birds of the other hemisphere, yet, 
when we regard the comparative defici- 
ency of the land in south latitudes all 
round the world, it is obvious that the 
feathered population of such as now- 
adays exists can exert but little influ- 
ence.” 
A nother and more speculative rea- 
son for the limitation of periodi- 
cal bird movement in the southern 
hemisphere has to do with the theory 
which connects present day migration 
with the geographical source, or point 
of original dispersal, of the various 
groups of migratory birds. It is an ac- 
cepted fact that many of the higher 
families of birds, such as the pipits, for 
instance, which are now of almost world- 
wide distribution originated somewhere 
in the northern continents, probably in 
central Asia, and thence radiated through 
Europe, Africa, both Americas, and 
many of the outlying islands. When 
birds of this kind were driven from their 
northern ranges by the ice invasion of 
the Glacial Epoch, some of the species 
only bided their time before following 
back the retreating cold and reoccupy- 
ing more and more of their old ranges, 
the constantly increasing seasonal oscil- 
lations eventually becoming fixed as the 
instinct of migration. According to this 
hypothesis, the birds of the southern con- 
tinents were not sufficiently distant from 
the tropics to be so affected by the Glacial 
Period, and, moreover, many of the 
groups then existing south of the equator 
have become extinct, and have been re- 
placed by invaders from the north. 
Having now discussed briefly some of 
the theoretical reasons for the relatively 
slight development of bird migration on 
the southern continents, let us consider 
two or three examples from the scant 
supply of scientific information which 
proves that certain land birds, breeding 
in temperate regions south of the equa- 
tor, do, nevertheless, make seasonal mi- 
grations into the tropics. In Argentina, 
South Africa Australia, and New Zea- 
(CONTINUED ON PAGE 189) 
