1903] Keays Notes on the Size of Hawks' Eggs. 201 



NOTES ON THE SIZE OF HAWKS' EGGS. 



By J. E. Keays. 



(Read before the Ornithologfical Section of the Entomological Society of 



Ontario.) 



A measurement and comparison of the cubic contents of the 

 eggs of the red-shouldered and red-tailed hawks, with the 

 addition of the measurements of a small series of broad-winged 

 and Swainson's hawk. In making the following measurements, I 

 am indebted to Mr. W. E. Saunders for the use of his collection 

 and for notes on the same. 



In all, eighty-five eggs of red-shouldered, seventeen of red- 

 tailed, three of broad-winged, and six of Swainson's hawk, have 

 been measured, and although no large sets of red-tailed were 

 available, the measurements go to i-how, that presuming that 

 every two sets of red-tailed hawk contained five eggs unitedly 

 (which in this locality is far above the average), still the average 

 set of red-shouldered would exceed that of the red-tailed by nearly 

 15 cc, and six of the twenty five sets of red-shouldered 

 measured, are greater than an average set of three red-tailed, 

 while two others are almost equal. 



Of the eighty-five red-shouldered eggs, only one exceeds the 

 average red-tailed in size, although four others are within a small 

 fraction of a cc. of being equal to it. 



An article published in "The Ornithologist and Oologist," 

 1886, page 118, entitled : "The Relative Size of Eggs of the 

 Red-tailed Hawk to the Parent Bird," proves with but little doubt, 

 that the ' larger the female of a species, the larger the egg 

 deposited by her. Accepting this as a fact, it would now be of 

 interest to compare the female birds of this species, not by 

 measurement but by weight, for although the red-tailed hawk is 

 apparently a much larger bird, its feathers are longer and looser, 

 and there is a doubt in my mind whether it weighs as much more 

 as it appears to. 



It would also be of interest to compare the relative weights 

 of both these birds with the cubic contents of sets deposited by 



