Age changes of plumage structures in non-passerines

Report on

Firsova, L.B. (1975): Age changes of plumage structures in non-passerines. Ornithological research at Far East: Proceedings of Biology & Soil Institute FEB AS USSR, 29 (132): 26-39

(APUSlist No. 3483)

by IGOR FEFELOV

The publication treats the change of plumages in the development of embryos and chicks of 35 species of 15 non-passerine bird orders.

The study concentrates on the structures which form embryonal and postembryonal plumages. A relation between embryonal and postembryonal structures was found, and their connections during the chick plumage forming are stated.

The Black Swift (Apus apus) has no embryonal plumage. The nest plumage contains juvenile feathers (pennae), and downy feathers (plumulae) growing from feather nipples that have been inactive in the embryonal phase of the development. It is different from many other bird orders in which downy feathers replace the embryonal plumage and grow from the same feather nipples. Both feather types are double-shafted, having the main and a second (additional) shaft. Downy feathers are forming a relatively dense warming layer under the main feathers.
Apodiformes together with Columbiformes, Strigiformes, Caprimulgiformes, Coraciiformes, and Picifiormes form a group which nest plumage has no or almost no a layer of the downy feathers which may be present only at a periphery of apteries. Galliformes are near to but significantly different from it in plumage.

A results of the study is that bird plumages (embryonal as well as postembryonal ones) are very ancient structures, that appeared during the early forming of bird orders. According to the author's opinion, this is an additional argument pro the theory that argues on a primarity of a contour feathers (plumae) and a secondarity of all down-like structures.