Visual display of the Aldo Leopold papers : 9/25/10-6 : Writings

				
TH    RLLTO17S OF WEIGHTS, BODY DIMENIONS, AND SEX 
Aldo  epl 
Sinc 1       I have recorded the weights of some 600 
6noks of fifteen species killed mostly in the upper Rio Grande 
Valley of New Mexico. The seasonal variations in l*eights and 
their apparent relation to 2plumage changes have been described 
in previous papers. 
It occurred to me that duck hunters have a further 
opportunity of contributing to ornithology by determining the 
interrelations of weight and various body measurements. Ac- 
cordingly, ea   body measurements were taken on 23 mallards 
killed during December, 1922, October and Deoember, 1923, and 
January, 1924, at various points in the upper Rio Grande Valley 
of New Mexicb, and on 21 mallards killed in Henderson County, 
Illinois, November 5-7, 1925. All these birds were weightd 
on the same scales, but unfortunately the body measurements, 
with the exoeption of bill and length, are not comparable 
throughout. In the New Mexico birds, spread was taken; in IlUiois 
the standard wing measurement. Length of foot was taken in New 
Mexico, but not in Illinois. This lack of standardization 
prevented complete statistical analysis of the non-standardiz- 
*&:Admensions. 
"Notes on the weights & plumage of ducks in New Mexico" Condor

XX, Mayo 1919, pp.128-129. 
2 
"Weights & plumage of ducks in the Rio Grande Valley", Condor
  , 
May, 1921, pp. 85-86.*