>EITEMBER 



1S83.] 



SCIENCE, 



303 



ami vice versa. The eggs of the former are 

 dark green ; of the latter, light bhie. No act 

 indicative of recognition of the change was 

 observed. I placed eggs of the song-sparrow 

 (Melospiza melodia) in the nest of a pce-wee 

 (Sayornis fuscus), and vice versa. The flj-- 

 catchers rejected the eggs of the sparrow^ ; but 

 the latter accepted the situation, although dis- 

 turbed by it. Many other changes were made, 

 with similar results ; and I concluded, that, un- 

 less the eggs were greatly different in size and 

 color, about one-half would be accepted ; but, 

 when a single egg was placed in the nest of 

 another bird, it was destroyed in nearly ever}- 

 case. This I found to be true, even when I 

 tested such birds as are subjected to the annoy- 

 ance of the cowpeu bird's egg being deposited 

 in their nests. I was surprised at this result, 

 and am led to believe that large numbers of 

 the eggs of this bird are destroyed. It is well 

 known that our summer warbler frequently out- 

 wits the cowpen bird b}- building a new nest 

 directly above the old, — a two-story nest, in 

 fact, — and leaves the egg that has been left to 

 her care to rot in the basement, while she 

 rears her young on the floor above. It will be 

 seen that from these experiments no very posi- 

 tive results were obtained. I did note, how- 

 ever, that, where the change was accepted, it 

 was not because it passed uhnoticed. but was 

 submitted to, notwithstanding the evidences of 

 much misgiving on the part of the birds. In 

 one case, the nest was practically deserted for 

 twenty-four hours, and the eggs were chilled 

 in consequence. The birds sat upon them for 

 live days, when, as the}' did not hatch, the 

 nest was abandoned. In previous years I 

 have made these changes occasionally with 

 success, but was not able to determine that 

 the young were recognized as not the offspring 

 of the parent birds. In such cases the young 

 were tended with the usual care up to the time 

 for leaving the nest. This m.ay possibly be 

 indicative of stupidity. It appeared so to me 

 at the time ; but I am now disposed to see in it 

 an indication that the maternal instincts here, 

 as in other cases I have mentioned, overcame 

 all other feelings, and that the fact was accepted 

 by the birds with as good grace as they could 

 command. 



The co-operation of birds, when construct- 

 ing their nests, is a subject that demands a 

 good <leal of close attention, and is one surely 

 worthy of more systematic observation than 

 has as yet been given it. The man\- ways 

 in which birds assist each other in nest-build- 

 ing offer, perhaps, the clearest evidence that 

 they have a very intelligent notion of what 



they are doing, or propose to do. I feel war- 

 ranted at the outset in making the somewhat 

 startling assertion, that the choice of location 

 for a nest is made only after protracted joint 

 examination of suitable sites, and is the choice 

 of both birds. I doubt if it ever happens 

 that one of a pair of birds ' gives in ' to its 

 mate. Certainly such a thing .as madame 

 giving up to her lord is unknown in the bird- 

 world. My impression is, that the female 

 birds of every species are exacting, obstinate, 

 and tyrannical. I have seen marked instances 

 of this among house-wrens, pee-wees, and 

 even known a cooing turtle-dove to exhibit 

 unmistakable evidences of a quick temper. 

 Tliese may seem to be trivial matters, and not 

 within the range of the scientific study of 

 animal intelligence ; but it is an error to look 

 upon such proofs of individuality in this light : 

 the}- are among the most convincing evidences 

 of a high degree of intelligence. If a hun- 

 dred or more nests of the same species of 

 birds are carefully compared, it will be found 

 that "there is a considerable range of variation 

 in their construction, and a varying degree of 

 merit in the skill shown by the builders. Is 

 not this evidence of different degrees of mental 

 strength occurring among birds of the same 

 species ? 



But to return to the subject of co-operation 

 in nest-building. J have found, that where 

 very long, fibrous materials are used, as in the 

 case of the globular nests of the marsh-wrens, 

 the birds work together in weaving the long 

 grasses that form the exterior. I have seen 

 one of these birds adjusting one end of a 

 long blade of rush-grass, while its mate held 

 the other end, until the former had completed 

 its task to its satisfaction. It was evident that 

 the weight of the ril>bon-like growth that the 

 bird was using, quite a metre in length, was 

 too heavy to be moved to and fro, and at the 

 same time prevented from slipping from the 

 unfinished nest. Only by assistance could 

 such materials be utilized, and only by intel- 

 ligent joint labor could these little birds build 

 such large and complete globular nests. Many 

 birds, too, have been known to jointly carr}- 

 away a long string or piece of muslin too 

 heavy or cumbersome for either one to move. 

 Again : materials are often brought by one of 

 a pair of birds to a nest which thd other con- 

 siders unsuitable, and fierce quarrels often 

 arise from this circumstance. In such cases 

 we have instances of a ditference of opinion 

 among birds, which is a marked indication 

 of mental activity. 



CiiAKLEs C. Abbott, M.U. 



