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Mar.,1911 NESTING OF THE CALIFORNIA CUCKOO IN LOS ANGELES COUNTY 71 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 nest 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 OF 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 was 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.