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Updated: August 11, 2024
Instincts comparable with habits, but different in their origin Instincts graduated Aphides and ants Instincts variable Domestic instincts, their origin Natural instincts of the cuckoo, molothrus, ostrich, and parasitic bees Slave-making ants Hive-bee, its cell-making instinct Changes of instinct and structure not necessarily simultaneous Difficulties of the theory of the Natural Selection of instincts Neuter or sterile insects Summary.
It is remarkable that some of the species, but not all, both of the Cuckoo and Molothrus, should agree in this one strange habit of their parasitical propagation, whilst opposed to each other in almost every other habit: the molothrus, like our starling, is eminently sociable, and lives on the open plains without art or disguise: the cuckoo, as every one knows, is a singularly shy bird; it frequents the most retired thickets, and feeds on fruit and caterpillars.
Some species of Molothrus, a widely distinct genus of American birds, allied to our starlings, have parasitic habits like those of the cuckoo; and the species present an interesting gradation in the perfection of their instincts. The sexes of Molothrus badius are stated by an excellent observer, Mr. Hudson, sometimes to live promiscuously together in flocks, and sometimes to pair.
Hudson says it is probable that they are occasionally parasitic, for he has seen the young of this species following old birds of a distinct kind and clamouring to be fed by them. The parasitic habits of another species of Molothrus, the M. bonariensis, are much more highly developed than those of the last, but are still far from perfect.
Monte Video Excursion to R. Polanco Lazo and Bolas Partridges Absence of Trees Deer Capybara, or River Hog Tucutuco Molothrus, cuckoo-like habits Tyrant- flycatcher Mocking-bird Carrion Hawks Tubes formed by Lightning House struck. July 5th, 1832 In the morning we got under way, and stood out of the splendid harbour of Rio de Janeiro.
In this case, as with that of the Molothrus or cuckoo, I can see no difficulty in natural selection making an occasional habit permanent, if of advantage to the species, and if the insect whose nest and stored food are feloniously appropriated, be not thus exterminated. This ant is absolutely dependent on its slaves; without their aid, the species would certainly become extinct in a single year.
The female lays her eggs in different nests and troubles herself no further about their fate. She seeks for her offspring a shelter which she does not take the trouble to construct, and moreover at the same time assures for them the cares of a stranger in place of her own. In North America a kind of Starling, the Molothrus pecoris, commonly called the Cow-bird, acts in the same careless fashion.
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