"Birds Who Feed their Young"

Altrices is the name given by Sundevall (K. Vet. Acad. Handl. 1836, page 64) to his first section of the Class Aves, comprehending those which "alunt pullulos" (feed their young), founded on the scheme of Oken (Lehrb. d. Zoologie, page 371), in opposition to Praecoces, the birds which at birth are more or less able to feed themselves, but subsequently abandoned by its inventor (Tentamen, p. XX., Nicholson's transl. p 26).

The division of the Class thus indicated has under various names been advocated by several authorities, and at first sight has a plausible appearance; but investigation shows (it has been argued) that it cannot be adopted. Doubtless the original Birds, like Reptiles, were Praecoces, and the Altrices are of later date. The existence of the numerous intermediate forms may thus be explained; but it follows that we cannot use as absolutely valid differentiating characters such as are afforded by the open or closed eyes of the young at birth, by their being clothed in down or naked, by their remaining in the nest or not, by their way of feeding themselves or being fed. It is possible that the transition from Praecoces to Altrices has been governed by purely external circumstances, which may still be in action-such, for instance, as the nest being built high above the ground or water. There are many Altrices whose whole anatomical structure proves them to be more nearly related to certain groups of typical Praecoces than they are to other Altrices. These circumstances as fully explained (Jenaisch. Zeitschrift, 1879, p. 385, and Bronn, Thierreich, Aves. p. 701) lead to the following divisions of birds in regard to their development:-

1. Praecoces or Nidifugae

Hatched with eyes open; thickly clad in down; able to run at once, or almost at once; and having such an amount of yolk stored in the abdomen as to render them for some time more or less independent of other food.

Birds in this division:

  • Ratitae
  • Crypturi
  • Gallinae
  • Laridae
  • Limicolae
  • Pteroclidae
  • Grallae
  • Anseres
  • Pygopodes
  • 2. Altrices or Nidicolae

    a. Lower Nidicolae
        Some hatched with their eyes open, others blind; covered or not with down; unable to leave the nest ; fed by the parents; amount of food-yolk very limited:
      Birds in this series
      • Spheniscidae
      • Steganopodes
      • Tubinares
      • Herodii
      • Pelargi
    b. Higher Nidicolae -
        Hatched in a helpless condition, blind; mostly naked, and for a long time nursed in the nest, the food - yolk having been used up at birth:
    The two series a and b stand phylogenetically parallel to each other.


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