and some just hatched, and at the same 

 time one or two fresh eggs. He was not 

 sure whether other cuckoos laid in the 

 same nest or whether the same bird con- 

 tinued to lay while sitting. From what 

 he has seen, however, he is inclined to 

 believe that the latter is the case, and 

 that 'the old bird utilizes the warmth 

 of the young first hatched to continue 

 the incubation of eggs subsequently 

 laid.' " Similar cases have been noted, 

 by other observers, in the breeding hab- 

 its of both the yellow-billed and the 

 Black-billed species. It is quite possible 

 that the slow development of the eggs 

 may be the sole explanation of the pecu- 

 liar and erratic nesting habits of the 

 American cuckoos, and Dr. Ridge way 

 has stated that "it is not at all improbable 

 that they may eventually become com- 

 pletely parasitic, like their European cou- 

 sins." 



The Black-billed Cuckoo is not a so- 

 cial bird, and it is seldom that any num- 

 ber of pairs are found nesting near each 

 other. Its nest is seldom placed higher 

 than six to eight feet above the ground 

 and is found in quite a variety of trees 

 and shrubs and in hedges. It has also 

 been known to nest on the ground and on 

 old logs. The nest is rather crudely con- 

 structed of twigs, shreds of fibrous bark 

 and small roots. The lining, when pres- 

 ent, consists of various soft vegetable 

 materials, such as fine fibers, moss, cat- 

 kins, dried leaves, the flowering heads 

 of some flowers, those of the cudweed are 

 often selected, and many other similar 

 materials. The nest is usually built in 

 retired places, and the bird will generally 

 desert it if it becomes aware that the site 

 has been discovered. The Cuckoo will 

 often remove its eggs to another nest if 

 it has been disturbed. The duties of in- 

 cubation and the case of the young are 

 shared by both parents. Major Bendire 

 says: "They appear to be devoted par- 

 ents, and the fact that they are occasion- 

 ally willing to abandon their young to the 

 mercy of foster parents appears rather 

 unaccountable, to say the least, especially 

 when it is positively known* that they oc- 

 casionally remove their eggs, as well as 

 the young, from one nest to another in 



order to better protect them from pos- 

 sible harm. In my opinion, the real 

 causes for the so utterly inconsistent be- 

 havior on the part of some of these birds 

 are not yet fully understood." 



Though the Black-billed Cuckoo has 

 been accused of destroying the eggs of 

 other birds, for the purpose of eating 

 their contents, the fact does not seem to 

 be well established. Even if they do 

 have this habit it is practiced to a very 

 limited extent and the very large num- 

 ber of injurious insect larvae that they eat 

 greatly overbalances the harm that they 

 do in -the destruction of a few eggs. The 

 home of this shy bird is among the 

 branches of trees, where it is concealed 

 by the foliage and where it quietly feeds 

 upon insect life. It destroys an enor- 

 mous number of leaf eating caterpillars. 

 It not only eats the smooth-skinned 

 species, but also the hairy and sharp- 

 spined ones that are usually rejected by 

 other birds and for which the Cuckoo 

 seems to have an inordinate taste. It 

 also eats grasshoppers, beetles and other 

 adult insects as well as a few snails and 

 a limited amount of the smaller fruits. 



That the Black-billed Cuckoo, as well 

 as the yellow-billed species, should be 

 protected and fostered has been well 

 shown by Mr. F. E. L. Beal, who found 

 that nearly one-half of the Cuckoo's food 

 consisted of injurious caterpillars. As 

 a result of his investigation he believes 

 that "in the cuckoos we probably have 

 one of nature's most efficient checks on 

 the increase of these harmful species. It 

 is said that hairy caterpillars are pro- 

 tected by their coats from the attacks of 

 the ichneumon flies ; if this be true, the 

 work of the cuckoos in destroying the 

 hairy species is complementary to that 

 of the ichneumons, which help to destrov 

 the smooth-coated caterpillars. Consid- 

 ering the number of grasshoppers, lo- 

 custs, and other insects that cuckoos eat 

 in addition to caterpillars, it is evident 

 that from an economic point of view these 

 birds are two of our most valuable 

 species, and as they have not been con- 

 victed of doing any harm, they should 

 be protected and encouraged in every 

 possible way." 



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