July, 1906 | 
LAND BIRDS OF SAN ONOFRE, CALIFORNIA 
93 
Five pairs of birds were watched to see if they would lay eggs of the same 
number, size, shape and markings from year to year. Three pairs of birds occu- 
pied the same nests during the two years and the other two pairs each moved 
to other nests in the same grove. The individuals had certain characteristics, as 
dark or light plumage or a peculiar harsh note while one pair made themselves 
conspicuous by their silence; so identification was quite certain and we were 
reasonably sure that we did not get the pairs confused. 
In 1905 one pair produced a set of two eggs which measure 2.53 x 1.78, 2.55 x 
1.83 inches. One egg of this set was covered with clay colored markings which 
merged together forming a hazy cloud around the large end. The other egg was 
similar to this but the markings were of a vinaceous buff tint and surrounded the 
small end. This year a set of three eggs laid by the same bird measure 2.38 x 1.81, 
2.32 x 1.76, 2.42 x 1.78 inches. These eggs were evenly covered with splashes 
that vary in size from a pin point to 25 square millimeters and fade from a cinna- 
mon rufous to heliotrope purple. Thus it will be seen that these two sets differ, 
in number, size, shape and markings. 
Another pair laid three eggs last year which measure 2.34x1.87, 2.33x1.88, 
2.32x1.87 inches. Two of these eggs were covered about the little end with 
chestnut colored spots that were arranged in a concentric position around the 
small end. These spots were large and gradually faded from chestnut to hazel as 
they approached the end of the egg. The other egg had only a few scattering 
hazel markings. This year this pair laid four eggs which have almost identically 
the same ground color, shape and markings as last year’s eggs. The eggs meas- 
ured 2.28x1.86, 2.29x1.83, 2.29x1.84, 2.30x1.84 In this instance the bird laid the 
same type of eggs for two consecutive years. 
The third pair laid a set of two eggs in 1905. The ground color of these eggs 
was almost white. One egg was covered about the small end with clear-cut 
chestnut splashes that centered about the small end of the egg. The other egg 
had a few very small vinaceous spots scattered evenly over its surface. This year 
this pair laid a set of three eggs. The ground color of this set was darker than 
that of the other set. One egg was covered about the small end with heavy 
burnt umber splashes. The second egg had a number of large brown spots on the 
large end, while the third egg was covered over the large end with indistinct clay 
colored splashes. The two sets measure 2.35x1.82, 2.37x1.83 and 2.33 x 1.84, 2.28 
xi. 87 (the third egg was broken). 
The fourth pair laid two eggs this year as well as last year. The set last year 
had a dirty ground color and was marked with a few scattering hazel smudges. 
The eggs laid this year were nearly exactly the same in size, ground color, incu- 
bation and markings. 
The last pair laid a set of two in 1905. These eggs were small (2.23x1.73, 
2.30x1.78) and had a few heavy spiral vinaceous spots on the large end. Another 
set from the same pair of birds measure 2.33x189, 2.24x1.82 inches. One of these 
eggs was particularly handsome as it was heavily marked on the little end with 
heavy clear-cut cinnamon-rufous splashes. The other egg was similar only the 
markings were not so brilliant. 
These observations show that some pairs of red-tails lay the same shape, size, 
number and marked eggs, for two consecutive years. But in the present instance 
the majority did not do this. 
In 1904 we saw several Pacific horned owls, but they seemed to have almost 
disappeared in 1905. I was also informed that horned owls were rarely met with 
that season in the central part of the County, where they had formerly been com- 
