20 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
P. montanus, given by M. D’Orbigny. Although the main difference be- 
tween the two birds, is the colour of their breasts, yet it must be observed, 
that in the M. albogularis there is some indication of an incipient change 
from white to brown in the plumage of that part. But as M. D’Orbigny, who was 
acquainted with the young birds of the P. montanus, (of which he has given a 
figure), does not mention so remarkable a modification in its plumage, as must 
take place on the supposition of M. albogularis being an immature bird of that 
species ; and as the geographical range of the two is so very different, I am 
induced to consider them distinct. Moreover, on the plains of Santa Cruz, I saw 
several birds, and they appeared to me similar in their colouring. The M. albogu- 
laris is remarkable from the confined locality which it appears to frequent. A few 
pair were seen during the ascent of the river Santa Cruz, (Lat. 50° S.) to the Cor- 
dillera ; but not one individual was observed in any other part of Patagonia. 
They appeared to me to resemble, in their gait and manner of flight, the P. Bra- 
siliensis ; but they were rather wilder. They lived in pairs, and generally were 
near the river. One day I observed a couple standing with the Carranchas 
and M. pezoporus, at a short distance from the carcass of a guanaco, on which 
the condors had commenced an attack. These peculiarities of habit are described 
by M. D’Orbigny in almost the same words, as occurring with the P. montanus; 
both birds frequent desert countries ; the P. montanus, however, haunts the great 
mountains of Bolivia, and this species, the open plains of Patagonia. 
In the valleys north of 30° in Chile, I saw several pair, either of this species, 
or of the P. montanus of D’Orbigny, (if, as is probable, they are different) or of 
some third kind. From the circumstance of its not extending (as I believe) so 
far south even as the valley of Coquimbo, it is extremely improbable that it 
should be the M. albogularis , — an inhabitant of a plain country twenty degrees 
further south. On the other hand, the P. montanus lives at a great elevation 
on the mountains of Upper Peru ; and therefore it is probable that it might 
be found in a higher latitude, but at a less elevation. M. D'Orbigny says, 
“ Elle aime les terrains secs et depourvus de grands v6g4taux, qui lui seraient 
inutiles ; car il nous est prouv6 qu’elle ne se perche pas sur les branches.” 
In another part he adds, “ Elle descend cependant quelquefois jusque press de 
la mer, sur la cote du P£rou, mais ce n’est que pour peu de temps, et peut- 
&tre afin d’y chercher momentanement une nourriture qui lui manque dans son 
s6jour habituel ; peut-etre aussi la nature du sol l’y attire-t-elle ; car elle y 
trouve les terrains arides qui lui sont propres.”* This is so entirely the cha- 
racter of the northern parts of Chile, that, it appears to me extremely pro- 
bable, that the P. montanus, which inhabits the great mountains of Bolivia, 
descends, in Northern Chile, to near the shores of the Pacific ; but that further 
* Voyage dans l’Amerique Meridionale Partie, Oiseaux, p. 52. 
