360 PATAGONIAN EXPEDITIONS : ZOOLOGY. 



distributed over an entire continent become modified by circumstances in 

 the widely separated regions they frequent, or not, must be an interesting 

 subject of inquiry to naturalists. 



" The Glossy Ibis is very common all over the State of Buenos Aires. 

 They appear in spring ; but as their movements are very irregular, and 

 many individuals remain through the winter, their migrations are probably 

 not altogether dependent on atmospheric changes. They have a graceful 

 flight ; and when migrating, the flocks are seen to succeed each other in 

 rapid succession, each flock being usually composed of from fifty to a 

 hundred individuals, but sometimes of a much greater number. A body 

 of these birds on the wing is a most interesting sight — now soaring high 

 in the air, displaying the deep chestnut hue of their breasts, now descending 

 with a graceful curve towards the earth, as if to exhibit the beautiful metallic 

 green of their upper plumage. The flock is in the meantime continually 

 changing its form or disposition, as if at the command of a leader. One 

 moment it spreads out in a long straight line ; suddenly the birds scatter 

 in disorder, or throw themselves together like a cloud of Blackbirds ; as 

 suddenly they again re-form and proceed in the figure of a phalanx, half- 

 moon, or triangle. The fanciful notion will scarcely fail to suggest itself 

 to the beholder's mind that the birds go through these unnecessary evo- 

 lutions intelligently to attain greater proficiency in them by practice, or 

 merely to make a display of their aerial accomplishments. The Ibis has 

 another remarkable habit while flying ; it is not, however, a habit exclu- 

 sively confined to this species. The flock is sometimes seen as if seized 

 with sudden frenzy or panic, every bird rushing wildly away from itsfellows, 

 and descending with a violent zigzag flight ; in a few moments the mad 

 fit leaves them, they rise again, reassemble in the air, and resume their 

 journey. 



" I should like to know if anything has been recorded concerning the 

 nidification of this bird. Having the four quarters of the globe for a 

 habitat, perhaps it is in no country more common than in this ; yet its 

 only breeding-place here that I have yet heard of is the Gualicho, a marshy 

 district about 170 miles south of Buenos; Aires city. I have not visited 

 this place in the breeding-season, but I have been told by people living 

 in its vicinity that the Ibises breed there in great numbers, and make their 

 nests close together. The nest is made of dry grass on the ground ; the 

 eggs are blue, and three in number. Baird, in his ' Synopsis of North- 



