ilar.a911 NESTING OF THE CALIFORNIA CUCKOO IN LOS ANGELES COUNTY 
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Eggs are generally deposited daily until the set is complete. This, however, is 
not always true, and sometimes, as in the case of the cuckoo’s big cousin, the 
Road-runner, fresh, incubated eggs and young may be found in the same nest at the 
same time. It is a very common thing to find two types of eggs in the same nest, 
undoubtedly laid by the same bird, part of the set being sharp pointed and the 
others blunt ended. They also vary considerably in size. The average size of 
twenty eggs is .96X1.29. The largest is 1.02X1.35, the smallest .85X1.24, and a 
runt measures .66X.87. 
In the majority of cases the Cuckoo builds its own nest, but in some instances 
it will appropriate an abandoned nest of the Mourning Dove, Black-headed Gros- 
beak, and possibly other birds. On June 22, 1902, I took two sets of Cuckoo’s 
eggs from old Black-headed Grosbeak’s nests. It will also on rare occasions de- 
posit its eggs in a ne.st already containing those of other birds. The following 
instances of this occurrence have come to my attention. On July 12, 1903, my 
brother took a set of Cuckoo’s from a Dove’s nest which contained three eggs of 
Fig. 31. NEST or CALIFORNIA CUCKOO, JULY 24, 1910 
the Cuckoo and one of the Dove; and on July 14, 1907, he found a nest of House 
Finch containing one egg of the Cuckoo and two of the finch. As no birds were 
seen near the nest we left it and returned a week later; on this date only the egg 
of the Cuckoo remained, both eggs of the finch being broken. 
The nests as built by the Cuckoos themselves are considerably different from 
those of the Mourning Dove, both in material and location. They are composed 
almost wholly of dry willow twigs, lined either with green moss, green willow 
leaves, or fine straw, and are generally located near the extremity of a branch 
from three to twenty-five feet from the ground. I have examined over forty nests 
of the Cuckoo, but have failed to find a single instance where the nest w^as not 
built in a willow. I have never seen a nest built by a Cuckoo placed close to the 
trunk of a tree, in the manner so common to the Dove. 
A typical nest measures: outside diameter nine inches, depth four inches; in" 
side diameter three and one-half inches, depth one and one-half inches; it re- 
sembles a nest of the Pasadena Thrasher though not so bulky. 
