The Origin of High Andean Birds 
Biogeographers attempting to explain the complex history 
of birds living in the high Andes of South America 
must be part scientist, part detective 
by Francois Vuilleumier 
Breathtakingly beautiful at times, 
with a palette of bright colors under 
the hot, midday sun, but forbidding 
at others, with strong winds, hail- 
storms, persistent fogs, and the 
numbing cold of early morning, the 
high-altitude realms of the Andes con- 
tinue to draw me back. Since 1964 
I have made six expeditions, totaling 
about twenty months, that have taken 
me all along the Andean backbone, 
from Venezuela to northern Patago- 
nia. Why? Because the Andes are, as 
ornithologist Frank M. Chapman put 
it half a century ago, “A New World.” 
Geologically recent, this narrow, 
4,000-mile-long mountain chain pro- 
vides the biogeographer with a won- 
derful setup for inquiries about fun- 
damental evolutionary problems. The 
paramos of the Venezuelan and Co- 
lombian Andes — wet, grassy alpine- 
like areas extending from 10,500 feet 
up to the snowline — are islands of 
open vegetation separated from each 
other by lower-altitude cloud forest. 
Farther south, in Peru and Bolivia, 
the high-altitude zone, known as puna , 
broadens into an arid and sparsely 
vegetated plateau stretching to the ho- 
rizon. Not surprisingly, paramo and 
puna habitats have little in common 
with the steaming lowland or the cool 
montane forests found in other parts 
of South America. But they also share 
little with the hot, grassy savannas 
of Venezuela or the open shrublands 
of Brazil. The high Andes are more 
like the Patagonian steppes at the far 
south of the continent. 
The resemblance between habitats 
of the high Andes and Patagonia ap- 
plies to the bird fauna as well. An 
ornithologist familiar with Patagonian 
birds who was transported 1,500 miles 
north to the Bolivian high plateau 
would feel ,at home. The two areas 
share a number of genera and several 
species; even the missing families are 
the same. How, then, did the high 
Andean birds evolve? Do they derive 
from Patagonia or do Patagonian birds 
derive from the high Andes? How 
much of the fauna is the result of 
David Ewe 
