Individuality in Eggs of Particular Pairs 
of Birds. 
(RRAD BEFORE THE LINN AZAN SOCIETY OF NEW YORK ) 
OLOGISTS make a great point of 
securing series of sets of eggs of cer- 
tain species of birds, intending by a 
completed series, which may consist of 
from a dozen to one hundred or more sets 
of a kind, to show the true type of the par- 
ticular species’ eggs, with all the principal 
variations in size, coloration, markings, etc. 
Mr. A. W. Johnson, formerly ot England, 
but now of California, once remarked to 
me that his large series of eggs of the Golden 
Eagle (Aguila chrysetos) was almost com- 
plete. Yet I feel that I may confidently 
affirm that with the eggs of certain species, 
and Golden Eagle’s particularly, such a 
thing as series, in the sense of possible 
‘“completeness,’’ is practically a myth. 
I think investigation, which has hitherto 
been practically lacking, will prove it to be 
a general law that eggs of monogamous 
birds like the Golden Eagle show a remark- 
able individuality from year to year in 
size, shape, coloration and markings—some- 
times in allof these particulars, and always 
in one or more. 
I have had exceptional opportunities in 
Santa Clara and San Benito counties, Cali- 
foinia, to study individuality in <Aguzla 
chrysetos, which it is generally conceded 
remains paired for lite and occupies the 
same nest for many years. In case they 
are Wuch disturbed or the nest is destroyed 
by the elements, which occasionally hap- 
pens, they commonly build a new nest 
quite near the old one, trom a seeming 
attachment to the locality, so that it is 
easy in that region to keep track of the 
nidification each year of a particular pair. 
I have shown in notes which appeared in 
“Zoe’’? and afterward in Major Bendire’s 
“‘Life Histories,’’ that some of my pairs of 
Eagles, which became familiars after years 
of observation, possess marked individuality 
as shown in their habits. It is to their 
eggs, however, that I would now draw 
especial attention. I visited the nests of 
some eight pairs of Golden Eagles for 
almost ten years successively, and while I 
came to know some of the birds, I became 
so familiar with the character of the eggs 
laid by isolated pairs that I would in most 
cases know exactly what to expect before 
climbing to a nest—which were the hand- 
THE NIDOLOGIST 5I 
somest eggs, which very large, which more 
rounded in form, and so on. 
Mr C. Barlow, of San Jose, California, 
was furnished with a map by which he 
might visit some of my Eagles’ nests the 
past season, and succeeded in collecting two 
sets of eggs from them. He wrote me 
from which nests he had secured the sets. 
I then described the eggs to him from 
memory of others taken from the same 
pairs. So well did the descriptions apply 
that he was forced to admit they were very 
striking, though having previously num- 
bered himself among the incredulous. 
In one of these sets the eggs were unusu- 
ally large and delicately and beautifully 
marked all over. The other set was quite 
a different type, not so large, and more 
rounded. 
Major Charles E. Bendire, in his “Life 
Histories of North American Birds,’’ states 
of the Golden Eagle: ‘‘I am inclined to 
believe that they remain mated for life, not- 
withstanding the eggs differ very greatly in 
markings from year to year, although com- 
ing from the same nest and evidently from 
the same pair of birds.” Here is testimony 
directly opposed to my own, but with due 
deference to so high and conservative an 
authority in Oology, I question if his obser- 
vations on the nesting of this species were 
so fully extended and continuous as to war- 
rant this conclusion. 
Mr. A. H. Frost, of New York, informs 
me that he has noticed a very marked sim- 
ilarity between two sets of eggs of this 
Eagle in his collection, which were secured 
by Denis Gale in Colorado, from the same 
nest in two successive years. Mr. J. Par- 
ker Norris, Jr., who has found a prodigious 
number of nests of the Kentucky Warbler 
of late years, stated to me that he had ob- 
served very distinct individuality in quitea 
number of instances in sets he presumed to 
belong to particular pairs of these Warblers. 
It is well known that the “J. P. N.” 
collection is rich in its series of sets of eggs 
of the Red-shouldered Hawk, collected by 
Mr. C. L,. Rawson, of Norwich, Conn., the 
famous ‘‘J. M. W,’’ and Mr. Norris informs 
me that Mr. Rawson, who collected syste- 
matically from his Red-shouldered Hawk 
circuit for many years, had recognized 
strong individuality in the eggs of particu- 
lar pairs. 7 
Mr. D. A. Cohen has noted in THE Nip- 
OLOGIST similar instances in the case of the 
Spurred Towhee going to prove individu- 
