A Guide For Aging Duck Broods In The Field

J. B. Gollop, Canadian Wildlife Service,

and

W. H. Marshall, University of Minnesota,

for

Mississippi Flyway Council Technical Section

Waterfowl management relies heavily on production data. Whether the objective is precise production measurements to evaluate population mechanics or production trend measurements as a basis for sound regulations, the brood is the focal point at present. Waterfowl technicians involved in brood studies have for several years recognized the need for a brood age classification system which would lend uniformity to their reporting. In 1937, J. H. Stoudt used three plumage classes in his work (7). In 1950, U.S.F.W.S. personnel devised and used six plumage classes in their breeding ground surveys. However, little was known about the ages involved in either case. L. H. Blankenship, in 1951, described plumage stages at weekly intervals for six species of dabblers based on field observations of wild, known-aged broods (1). C. D. Evans and K. E. Black added data on ages by plumage classes from 1950 to 1953. Southwick reported on studies of hand-reared birds (6). In May, 1953, the Mississippi Flyway Council's Technical Section provided the funds for a preliminary report on "Techniques For Brood Production Studies" (2). Additional information was obtained during the 1953 breeding season which made a revision advisable. The present authors have attempted to assemble the data currently available and the Technical Section has again financed the publication of this booklet and its distribution to waterfowl workers in the four flyways. Major contributions to this report have been made by Milton Weller who supplied information on the redhead and drew Figure 1, Alex Dzubin who provided the results of his canvasback study, and Dr. H. C. Mendall who presented development data on ring-necked and black ducks. To a large extent this edition relies on the foundation laid by L. H. Blankenship, C. D. Evans, M. H. Hammond and A. S. Hawkins in 1953.

The scope of this booklet differs somewhat from its predecessor; it attempts to deal only with the complexities of aging young by plumage classes and the use of age data in calculating production. If, after field use, improvements can be suggested, it will be appreciated if they are sent to W. H. Marshall, 300 Coffey Hall, University Farm, St. Paul 1, Minnesota.

This resource is based on the following source: 
Gollop, J.B. and W.H. Marshall.  1954.  A guide for aging duck broods in the 
     field.  Mississippi Flyway Council Technical Section.  14pp.
This resource should be cited as: 
Gollop, J.B. and W.H. Marshall.  1954.  A guide for aging duck broods in the 
     field.  Mississippi Flyway Council Technical Section.  14pp.
     Northern Prairie Wildlife Research Center Home Page. 
     http://www.npwrc.usgs.gov/resource/tools/ageduck/ageduck.htm
     (Version 14NOV97).

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