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Bulletin - United States National Museum - si-pddr - Smithsonian ... Bulletin - United States National Museum - si-pddr - Smithsonian ...

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18 BULLETIN 133, UNITED STATES NATIONAL MUSEUM Others may be added as the southern distribution of birds in Patagonia becomes better known. In this zone Vultur gryphus finds its lowest point of regular occurrence. A considerable number of species range in both Upper Austral and Transition Zones. TEMPERATE ZONK As field work did not carry me above the Upper Austral Zone, I am dependent on the accounts of other travelers for information on this higher zone. A statement regarding the Temperate Zone as it is found in Avestern Patagonia is based mainly on Peters' remarks concerning his Zone 3, which he says covers the east Andean slopes in western Rio Negro and is characterized by a temperate forest with normal rainfall. Part, at least, of the forest of south- ern Chile, where precipitation is heavy, must belong here, but the southern limit of this zone is uncertain. In passing north along the Andes, tree growth becomes scanty a short distance north of Lago Nahuel Huapi, and in w^estern Nfeuquen entirely disappears. Beyond, through the length of Argentina, the higher mountain slopes are arid and bare with scant vegetation, which is restricted mainly to the valley floors and the gentler inclines above. The bolder mountain masses show bare rock exposures, in the main too young to have weathered into permanent soil. Zonal delimi- tation under these conditions is difficult. In Eio Negro Peters placed the upper limit of his Zone 3 at about 1,000 meters. The dry, arid slopes to the northward have forced zonal lines rather abruptly upward as in crossing on the trans-Andean railroad from Mendoza it appeared to me that Temperate Zone began at the Rio Tupungato at about 2,800 meters' altitude. The following birds include mainly species of the southern forested region. The list may be expanded by including some of the water birds peculiar to the Magellanic region. Attagis gayi gayi. Chloroenas araucana. Microsittace ferruginca. St7'ix rufipes. Ipocrantor magellaniciis. Cinclodes patagoiiicus rupestris. Sylviorthorhynchus desmurii. Pygarrhichas alho-gularis. Scytalopus magellanicus. Scelorchilus ruhccula. Ftei-optochos tarnii. Agriornis livida fort is. Lichenops perspicillata andina. Melanodera mclanodera. Melanodera xanthogratnnia. Above the Temperate Zone is a great Paramo Zone extending to the line of perpetual snoAvs on the mountains, a cold, bleak region with little bird life, at present insufficiently known, that will be dis- missed at this place with bare mention.

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 19 NOTES ON MIGRATION Though ordinarily we may think of extensive and widespread migratory movements among birds as something more or less pe- culiar to the Northern Hemisphere, yet on investigation we find pronounced migrations among the birds of South America, espe- cially in the southern part of the continent. The migratory flight in the latter region may be considered as of two kinds, first, that of birds come from North America for the period of the northern winter, and, second, that of species that pass south to breed, and with the close of the period of reproduction withdraw again toward the Tropics. Though a number of passerine and other birds from North America come conmionly to the northern part of South America, comparatively few of these species pass as far south as the section covered by Paraguay, Uruguay, Argentina, and Chile. Among the few of the smaller land species that perform this extended flight, the barn swallow and the bobolink are worthy of mention, especially the latter, as though the barn swallow occurs during the northern winter months from the West Indies southward, the bobo- link withdraws wholly into the Chaco. The yellow-billed cuckoo, cliff swallow, olive-backed thrush, nighthawk, and Swainson's hawk are of more or less common occurrence in the northern half of the region in question, but are not found in abundance. In addition to these may be mentioned the parasitic and long-tailed jaegers (that have been recorded casually, but that occasionally at least, occur in great abundance along the coast of Buenos Aires), Cabot's, royal, and arctic terns, and the red and northern phalaropes. Tl>e great body of North American migrants, how^ever, are shore birds, some of which as the two yellowlegs, the sanderling, and the spotted sandpiper have extended winter ranges, while others as the Hud- sonian godwit, the upland plover, the buff-breasted, pectoral, Baird's, and white-rumped sandpipers find in the pampas and in Patagonia their winter metropolis. With these last may be men- tioned the Eskimo curlew now nearly, if not actually, extinct. A few individuals of these northern species arrive in the south in July and August, but their main southward flight occurs from September to November. In other words, they pass south with the coming of fall in the Northern Hemisphere, and below the Equator follow the advance of southern spring to their winter home, remain during the southern summer, and with the coming of colder weather in February and March withdraw northward until they cross the Equator and follow the northern spring in its advance to their breeding grounds in the northern United States, Canada, and Arctic

18 BULLETIN 133, UNITED STATES NATIONAL MUSEUM<br />

Others may be added as the southern distribution of birds in<br />

Patagonia becomes better known. In this zone Vultur gryphus<br />

finds its lowest point of regular occurrence. A con<strong>si</strong>derable number<br />

of species range in both Upper Austral and Tran<strong>si</strong>tion Zones.<br />

TEMPERATE ZONK<br />

As field work did not carry me above the Upper Austral Zone,<br />

I am dependent on the accounts of other travelers for information<br />

on this higher zone. A statement regarding the Temperate Zone<br />

as it is found in Avestern Patagonia is based mainly on Peters' remarks<br />

concerning his Zone 3, which he says covers the east Andean<br />

slopes in western Rio Negro and is characterized by a temperate<br />

forest with normal rainfall. Part, at least, of the forest of south-<br />

ern Chile, where precipitation is heavy, must belong here, but the<br />

southern limit of this zone is uncertain. In pas<strong>si</strong>ng north along<br />

the Andes, tree growth becomes scanty a short distance north of<br />

Lago Nahuel Huapi, and in w^estern Nfeuquen entirely disappears.<br />

Beyond, through the length of Argentina, the higher mountain<br />

slopes are arid and bare with scant vegetation, which is restricted<br />

mainly to the valley floors and the gentler inclines above. The<br />

bolder mountain masses show bare rock exposures, in the main<br />

too young to have weathered into permanent soil. Zonal delimi-<br />

tation under these conditions is difficult. In Eio Negro Peters<br />

placed the upper limit of his Zone 3 at about 1,000 meters. The<br />

dry, arid slopes to the northward have forced zonal lines rather<br />

abruptly upward as in cros<strong>si</strong>ng on the trans-Andean railroad from<br />

Mendoza it appeared to me that Temperate Zone began at the Rio<br />

Tupungato at about 2,800 meters' altitude.<br />

The following birds include mainly species of the southern<br />

forested region. The list may be expanded by including some of<br />

the water birds peculiar to the Magellanic region.<br />

Attagis gayi gayi.<br />

Chloroenas araucana.<br />

Micro<strong>si</strong>ttace ferruginca.<br />

St7'ix rufipes.<br />

Ipocrantor magellaniciis.<br />

Cinclodes patagoiiicus rupestris.<br />

Sylviorthorhynchus desmurii.<br />

Pygarrhichas alho-gularis.<br />

Scytalopus magellanicus.<br />

Scelorchilus ruhccula.<br />

Ftei-optochos tarnii.<br />

Agriornis livida fort is.<br />

Lichenops perspicillata andina.<br />

Melanodera mclanodera.<br />

Melanodera xanthogratnnia.<br />

Above the Temperate Zone is a great Paramo Zone extending<br />

to the line of perpetual snoAvs on the mountains, a cold, bleak region<br />

with little bird life, at present insufficiently known, that will be dis-<br />

missed at this place with bare mention.

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