Peter Pyle

As the title might suggest, this booklet has a very specific focus on the molting patterns of just the flight feathers of North American (north of Mexico) owls. Written in the standard scientific methods, this is a monograph that adds to the ornithological literature and knowledge.

Using over 2,400 specimens from museums, wings of the 19 normally occurring owl species underwent a variety of measurements. These measurements and notes were matched to the assigned age-code of each bird which was determined by the specimen’s plumage and tag information. The seven age-codes followed the calendar-based system used by the Bird Banding Laboratory (e.g., HY/SY, TY/4Y).

The information was summarized for each of the 10 genera of owls and not necessarily for each species. For the genus, a summary of findings was given for each age-code. These summaries offered detailed accounts of the wear, shape, and markings of the various secondary and primary feathers.

Nicely drawn black-and-white figures of feather detail help to illustrate the pattern of markings within the feathers as well as displaying their shapes between juvenile and adult.

For the ornithologist, owl enthusiast, or the intense birder, this monograph will be of interest.

I’ve listed several related books below…
1) Identification Guide to North American Birds: Part I by Pyle
2) Identification Guide to North American Passerines by Pyle et al.
3) Ageing North American Landbirds by Molt Limits and Plumage Criteria by Froehlich
4) Advanced Birding by Kaufman
5) Biosystematics of Sibling Species of Flycatchers in the Empidonax hammondii-oberholseri-wrightii Complex by Johnson
6) Bird-Bander's Guide to Determination of Age and Sex of Selected Species by Wood
7) Body Weights of 686 Species of North American Birds by Dunning
8) Identification guide to European Passerines by Svensson
9) Owls: A Guide to the Owls of the World by Konig et al.
10) Owls of the World: Their Evolution, Structure and Ecology by Burton… (plus d'informations)