The Zoologist — August, 1873. 3649 



every hen cuckoo with the faculty of laying eggs similar in colour to those 

 of the species in whose nest she lays, in order that they may he less easily 

 detected by the foster-parents, and that she only makes use of the nest of 

 some other species {i. e. of one whose eggs do not resemble her own) when, 

 at the time she is ready to lay, a nest of the former description is not at 

 hand. This statement, which concludes a long and interesting article on 

 the subject in the German ornithological journal ' Naumaunia,' for 1853, 

 has deservedly attracted much attention. English readers were presented 

 with an epitome of this article by Mr. Dawson Eowley in the ' Ibis ' for 

 ]865, and the Rev. A. C. Smith, after bringing it to the notice of the Wilt- 

 shire Archaeological Society in the same year, published a literal translation 

 of the paper in the ' Zoologist' for 1868. More recently, an excellent article 

 on the subject, by Professor Newton, has appeared in ' Nature' (18th Nov., 

 1869).* To enter fully upon the details of this interesting subject would 

 require more space than we have at our disposal ; we can only glance, there- 

 fore, at the general opinions which have been expressed in connection with 

 it. If the theory of Dr. Baldamus be correct, is it possible to give a 

 reasonable and satisfactory explanation of it? This question has been 

 answered by Professor Newton in the article to which we have just referred. 

 He says : — " Without attributing any wonderful sagacity to the cuckoo, it 

 does seem likely that the bird which once successfully deposited her eggs 

 in a reed wren's or a titlark's nest should again seek for another reed 

 wren's or a titlark's nest (as the case may be) when she had an egg 

 to dispose of, and that she should continue her practice from one season to 

 another. We know that year after year the same migratory bird will return 

 to the same locality, and build its nest in almost the same spot. Though 

 the cuckoo be somewhat of a vagrant, there is no improbability of her being 

 subject to thus much regularity of habit, and indeed such has been asserted 

 as an observed fact. If, then, this be so, there is every probability of her 

 offspring inheriting the same habit, and the daughter of a cuckoo which 

 always placed her egg in a reed wren's or a titlark's nest doing the like." 

 In other words, the habit of depositing an egg in the nest of a particular 

 species of bird is likely to become hereditary. This would be an excellent 

 argument in support of the theory, were it not for one expression, upon 

 which the whole value of the argument seems to us to depend. What is 

 meant by the expression " once successfully deposited"? Does the cuckoo 

 ever revisit a nest in which she has placed an egg, and satisfy herself that 

 her offspring is hatched and cared for ? If not (and we believe such an event 

 is not usual, if indeed it has ever been known to occur), then nothing has 

 been gained by the selection of a reed wren's or titlark's nest (as the case 

 may be), and the cuckoo can have no reason for continuing the practice of 

 using the same kind of nest from one season to another. While admitting, 

 * Reprinted in the ' Zoologist' (S. S. 3505). 



