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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.*
The following analysis and conclusions are offered in the full realization that a larger number of birds would be desirable, although some of the relationships indicated by the graphs are so positive that it seems doubtful whether more data would change them. The original purpose was to demonstrate a new way to make the game bag yield something more than meat, and this, at least, has been done. The task of analysis also clearly demonstrated the author's mathe- matical deficiencies, and while the very best mathematical methods have probably not been used, the work has been re- viewed by of the Forest Products Laboratory, who says - The clearest presentation will result, I think, from Llowing the analysisstep by step4and building up the conclu- Graphs 1 & 2 The birds were arranged in ascending order of weight New Mexico and Illinois separately, the weights plotted points, and the points Joined to form an unsmoothed "fre- noy curve" for weight. Next, the various body measurements were plotted for ea6h bird, arbitrarily adjusting the tertical scales so that the total range in each measurement would equal.on the graph, -2i