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Show 108 ZOOLOGY OF TilE VOYAGE OF THE BEAGLE. with the usual black kind, there were generally a few dull brown coloured ones, (Icterus sericeus of Licltt.) which I presume are the young. Azara states that the brown-coloured birds are smaller than the black glossy ones, and that they sometimes form one-tenth of the whole number in a flock. In the single specimen which I brought home, the size, with the exception of the length of the wing, is only a very little less. Sonnini, in his notes to Azara, considers the brown birds as the females; I can, however, scarcely believe that so obvious a solution of the difficulty could have escaped so accurate an observer as Azara, These birds in La Plata often may be seen standing on the back of a cow or horse. While perched on a hedge, and pluming themselves in the sun, they sometimes attempt to sing or rather to hiss : the noise is very peculiar; it resembles that of bubbles of air passing rapidly from a small orifice under water, so as to produce an acute sound. Azara states that this bird, like the cuckoo, deposits its eggs in other birds' nests. I was several times told by the country people, that there was some bird which had this habit; and my assistant in collecting, who is a very accurate person, found in the nest of the Zonot1·icltia ruficollis (a bird which occupies in the ornithology of S. America the place of the common sparrow of Europe), one egg larger than the others, and of a different colour and shape. This egg is rather less than that of the missel-thrush, being ·93 of an inch in length, and ·78 in breadth ; it is of a bulky form, thick in the middle. The ground colour is a pale pinkish-white, with irregular spots and blotches of a bright reddish-brown, and others less distinct of a greyish hue. This species is evidently a very close analogue of theM. peco1·is of North America, from which, however it may at once be distinguished by the absence of the glossy brown on the head, neck, and upper breast,-by the metallic blueness of its plumage in the place of a green tinge, and by its somewhat greater size in all its proportions. The young or brown-coloured specimens of these Molothri resemble each other more closely; that of the M. pecoris is of a lighter brown, especially under the throat, and the small feathers on its breast and abdomen have each an obscure dark central streak. The eggs of the Molothri, although having the same general character, differ considerably ; that of the M. pecoris being smaller and less swollen in the middle; it is ·85 of an inch in length, and •78 in breadth. Its colour cannot be better described than in the words of Dr. Richardson,..-it is "of a greenish white, with rather small crowded and confluent irregular spots of pale liver-brown, intermixed with others of subdued purplish grey." From this • Fauna Borealis, Birds, P· 278. Dr. Richardson states that the egg is only seven lines and a half in length. I presume the measure of eight lines, instead of twelve to tho inch must in this case have been used. I am much ~ndebted to the kindness of Mr. Y o.rrell for lending me an egg o; the Molotnrus pecoris, forming part of a collectiOn of North Americnn eggs in his possession. BIRDS. 109 description it is obvious that the egg of M ni:ger 1·s Jar d f h d . . · ger an o a muc re der tmt; the more promment spots also are larger the subd d b '• · similar in both. ' ue grey emg qUite If w~ were to judge fro~ habits alone, the specific difference between these two species. of Molothrus. m1g.h t well be doubted,, they seem c1 o se 1y t o resem bl e each ot~er m gen_eral habitS,-I_n manner of feeding,-in associating in the same flock with other buds, an~ e;en m such peculiarities as often alighting on the backs of ca~tle. The M. pecorzs, hke the M. niger, utters strange noises, which Wilson• describes " ~s a low_ spluttering note as if proceeding from the belly." It appears to ~e very mterest~ng thus_ to fin~ so close an agreement in structure, and in habits, b~tween alhed species commg from opposite parts of a great continent. Mr. Swamson t has remarked that with the exception of the Molotltrus, the cuckoos are the only birds which can be called truly parasitical; namely, such as "fasten themselves, as it were, on another living animal, whose animal heat brings their young into life, whose food they alone live upon, and whose death would cause theirs during the period of infancy." It is very remarkable, that the. cuckoos and the ~olot.hri, although opposed to each other in almost every hab1t, should agree m this strange one of their parasitical propagation : the habit moreover is not universal in the species of either tribe. The Molothrus, like our starling, is eminently sociable, and lives on the open plains without art or disguise:t the cuckoo, as every one knows, is a singularly shy bird; it frequents the most retired thickets, and feeds on fruit and caterpillars.§ AMBLYRAMPHUS RUBER. G. R. Gray. Oriolus ruber, Gmel. Amblyrnmphus bicolor, Leach. Sturnus pyrrhocephalns, Licl!t. Sturnella rubra, Vwill. Loistes erythrocephala, Swains. Clnss. Birds. This bird frequented marshy places in tLe neighbourhood of Maldonado, but it was not common there. It is more solital'y than the following allied species; I have, however, seen it in a flock. Seated on a twig, with its beak widely open, it often makes a shrill, but plaintive and agreeable cry, which is sometimes single * Wilson's American Ornithology, vol. ii. p. 162. t Magazine of Zoology and Botany, vol. i. p. 2I7. ~ See Aznra, vol. iii. p.I70. ; It appears that the eggs in the samo nest with that of the Molothrus pecoria, nre turned out by the parent birds beforo they aro hatched, owing to the egg of theM. peaoris being hatched in an unusually short time; in the cnse of the young cuckoo, as is well known, the young bird itself throws out its foster-brothers. Mr. C. Fox, however, (Sillimrm's American Journal, vol. xxix. p. 292), relates an instance of three young sparrows having been found alive with a Molothrus. |
