How often have I watched over the little bird in its nest, and marked the changes which day after day it exhibited: the unfolding of its first scanty covering of down, the sprouting of its plumelets, the general enlargement of all its parts! With what pleasure have I viewed the development of its colouring and the early manifestations of its future habits!
Amid these wonderful operations of Nature, there is one which has occasionally engaged my attention, and occupied my thoughts, ever since I first became acquainted with the bird of which I now proceed to speak.
The Cow Bird, which in form and character is allied to the Crow Blackbird, the Redwing, the Orchard Oriole, and other species, together with some of which it forms the genus Icterus, differs from these birds in one important circumstance, which approximates it to the Cuckoo of Europe, a bird entirely different in habits and appearance. Like that bird, it makes no nest of its own, but deposits its eggs, one at a time, in the nests of other birds, leaving them to the care of a foster-parent.
In the State of Louisiana, the Cow-pen Bird, or as it is also called, the Cow Blackbird, or Cow Bunting, is seen only at long intervals. Some years pass without the appearance of a single individual there. At other times immense flocks are observed mixing with the Redwings, Crow Blackbirds and Robins, searching about the farm-yards, the fields, and the meadows with great diligence for food. At such times they are easily approached, and are shot in great numbers, being considered more delicate and better flavoured than the species with which they associate, excepting the Robin. Like the Redwings, they seek the swamps and the margins of lakes and rivers, where they roost among the tall sedges, flags, and other aquatic plants. When disturbed in these retreats, they rise in a dense mass, perform various evolutions in the air, and alight again to resume their repose. At daybreak, they return to the cultivated parts of the country to search for food. In Georgia and South Carolina, they occur in great abundance every winter. Some also spend the winter in Virginia and Maryland, as well as in the States of Kentucky and Indiana, where I have observed them lingering about farm-houses and cow-pens during severe weather. Great flocks, however, retire much farther south. I have seen many of these birds passing high in the air, at mid-day, in the month of October, pursuing their course steadily, as if bent upon a long journey.
The Cow-pen Bird, after passing the winter in the Southern States, or in regions nearer the equator, makes its appearance in the Middle States about the end of March or beginning of April, arriving in small parties. Their flight is performed chiefly under night; and during the day they are seen resting on the trees, or frequenting the banks of streams in quest of food. They continue to be seen in small flocks until the beginning of June, when they disappear, the various flocks having successively passed northward.
Its flight is similar to that of the Redwing, with which it frequently associates in its rambles. During spring and summer it feeds on insects, larvæ and worms, frequenting the cornfields, meadows and open places.
The males and females arrive together; but contrary to the general practice among the feathered tribes, these birds do not pair. The males seem to regard the females with little interest. The numberless acts of endearment, the many carollings, joyous flights, and bursts of ecstatic feeling, which other birds display at the commencement of the breeding season, are entirely dispensed with. When a particular intimacy takes place between two individuals of different sexes, it soon ceases, and the same individuals mate with others. The sexual attachment intended for the benefit of the young brood does not take place, because in this species the young are not to be reared by their parents, but to be left to the care of birds of other kinds. The Cow-pen Buntings, in fact, like some unnatural parents of our own race, send out their progeny to be nursed.
When the female is about to deposit her eggs, she is observed to leave her companions, and perch upon a tree or fence, assuming an appearance of uneasiness. Her object is to observe other birds while engaged in constructing their nests. Should she not from this position discover a nest, she moves off and flies from tree to tree, until at length, having found a suitable repository for her egg, she waits for a proper opportunity, drops it, flies off, and returns in exultation to her companions.
The birds in whose nests the eggs of the Cow Bunting are thus deposited, are all smaller than itself. That which is most frequently favoured with the unwelcome gift is the Maryland Yellow-throat. The other species in which I have found the egg of the Cow Bird are the Chipping Sparrow, the Blue Bird, the Yellow Bird, several Fly-catchers, especially the Blue-grey and the White-eyed, and the Golden-crowned Thrush. The nests of these birds are very different in form, size and materials, as well as in position, some being placed high on trees, others in low bushes, and that of the Thrush on the ground.
It is also a very remarkable circumstance, that although the Cow-Bird is larger than the species in the nests of which it deposits its eggs, the eggs themselves are not much superior in size to those of their intended foster-parents. This is equally the case with the European Cuckoo, which selects, for the purpose of depositing its egg, the nest of the Titlark, Hedge-Sparrow, or some other small bird. And here, as in so many other cases, may we observe the adaptation of means to ends which nature has so admirably made. The egg of the Cuckoo, in fact, is not so large as that of the Skylark, a bird which, to the other, hardly bears the proportion of one to six. The intention here has not been by a similarity in size and colouring, to deceive the bird in whose nest the egg is placed, for, on all occasions, the individuals on which the gift have been bestowed, receive it unwillingly, and, in fact, manifest great alarm and resentment. On the contrary, the object has been to secure the development of the embryo, by adapting the size of the egg to the capability of imparting heat to it.