The explanation of the most striking features of the Dendrocolaptidae, their monotonous brown plumage, diversity of structure, versatile habits, and the marvellous development of the nest-making instinct which they exhibit is to be found, it appears to me, in the fact that they are the most defenceless of birds. They are timid, unresisting creatures, without strength or weapons; their movements arc less quick and vigorous than those of other kinds, and their flight is exceedingly feeble. The arboreal species flit at intervals from one tree to another; those that frequent thickets refuse to leave their chosen shelter; while those inhabiting grassy plains or marshes study concealment, and, when forced to rise, flutter away just above the surface, like flying-fish frightened from the water, and, when they have gone thirty or forty yards, dip into the grass or reeds again. Their life is thus one of perpetual danger in a far greater degree than with other passerine families, such as warblers, tyrants, finches, thrushes, &c.; while an exclusively insect diet, laboriously extracted from secret places, and inability to change their climate, contribute to make
The Woodhewer Family. 247
their existence a hard one. It has been with these birds as with human beings, bred in "misfortune's school," and subjected to keen competition. One of their most striking characteristics is a methodical, plodding, almost painful diligence of manner while seeking their food, so that when viewed side by side with other species, rejoicing in a gayer plumage and stronger flight, they seem like sober labourers that never rest among holiday people bent only on enjoyment. That they are able not only to maintain their existence, but to rise to the position of a dominant family, is due to an intelligence and adaptiveness exceeding that of other kinds, and which has been strengthened, and perhaps directly results from the hard conditions of their life.
How great their adaptiveness and variability must be when we find that every portion of the South American continent is occupied by them; for there is really no climate, and no kind of soil or vegetation, which does not possess its appropriate species, modified in colour, form, and habits to suit the surrounding conditions. In the tropical region, so rich in bird life of all kinds, in forest, marsh, and savanna, they are everywhere abundant--food is plentiful there; but when we go to higher elevations avd cold sterile deserts, where their companion families of the tropics dwindle away and disappear, the creepers are still present, for they are evidently able to exist where other kinds would starve. On the stony plateaus of the Andes, and on the most barren spots in Patagonia, where no other bird is seen, there are small species of Synallaxis, which, in their obscure colour and motions
248 The Naturalist in La Plata.
on the ground, resemble mice rather than birds; indeed, the Quichua name for one of these Synallaxes is ukatchtuka, or mouse-bird. How different is the life habit here from what we see in the tropical groups--the large birds with immense beaks, that run vertically on the trunks of the great forest trees!
At the extreme southern extremity of the South American continent we find several species of Cin-clodes, seeking a subsistence like sandpipers on the beach; they also fly out to sea, and run about on the floating kelp, exploring the fronds for the small marine animals on which they live. In the dreary forests of Tierra del Fuego another creeper, Uxyurus, is by far the commonest bird. "Whether high up or low down, in the most gloomy, wet, and scarcely penetrable ravines," says Darwin, "this little bird is to be met with;" and Dr. Cunningham also relates that in these wintry, savage woods he was always attended in his walks by parties of these little creepers, which assembled to follow him out of curiosity.
To birds placed at so great a disadvantage, by a feeble flight and other adverse circumstances, in the race of life bright colours would certainly prove fatal. It is true that brown is not in itself a protective colour, and the clear, almost silky browns and bright chestnut tints in several species are certainly not protective; but these species are sufficiently protected in other ways, and can afford to be without a strictly adaptive colour, so long as they are not conspicuous. In a majority of cases, however, the colour is undoubtedly protective, the