The displays of the wood-hewers, or Dendrocolap-tidae, another extensive family, resemble those of the tyrant-birds in being chiefly duets, male and female singing excitedly in piercing or resonant voices, and with much action. The habit varies somewhat in the cachalote, a Patagonian species of the genus Homorus, about the size of the missel-thrush. Old and young birds live in a family together, and at intervals, on any fine day, they engage in a grand screaming contest, which may be heard distinctly at a distance of a mile and a half. One bird mounts on to a bush and calls, and instantly all the others hurry to the spot, and burst out into a chorus of piercing cries that sound like peals and shrieks of insane laughter. After the chorus, they all pursue each other wildly about among the bushes for some minutes. In some groups the usual duet-like performances have developed into a kind of harmonious singing, which is very curious and pleasant to hear. This is pre-eminently the case with the oven-birds, as D'Orbigney first remarked. Thus, in the red oven-bird, the first bird, on the appearance of its mate flying to join it, begins to emit loud, measured notes, and sometimes a continuous trill, somewhat metallic in sound; but immediately on the other bird striking in this introductory passage is changed to triplets, strongly accented on the first note, in a _tempo vivace;_ while the second bird utters loud single notes in the same time. While thus singing they stand facing each other, necks outstretched and tails expanded, the wings of the first bird vibrating rapidly to the rapid utterance, while those of the second bird beat measured time. The finale consists of three or four notes, uttered by the second bird alone, strong and clear, in an ascending scale, the last very piercing.