918 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVI II. 



direct attention to the fact that they have a nest. Mr. Edmund Selous in his 

 Bird Watching states that he has observed the snipe, the Arctic Skua and the 

 nightjar act thus when they have eggs. 



Similarly most people have heard the noise which all bulbuls make when 

 anyone approaches their nest ; they do this whether it contain eggs or young 

 ones. Now, the making of such noise must tend to be harmful since it attracts 

 attention to the nest which might otherwise pass unobserved. We know that 

 at the nesting season birds are in a very curious mental state. Were they not, 

 they would not sit for hours warming their eggs. 



No bird can possibly be acting intelligently when sitting on its first clutch of 

 eggs ; it cannot know that they are going to yield young birds. Thus at the 

 nesting season birds are seized by a kind of mania. In such a state their mental 

 balance is easily upset, hence they perform strange antics when a dangerous 

 animal approaches the nest. These antics are the outward .expression of 

 the fact that they have temporarily lost their mental .balance. Such actions 

 tend to preserve the young birds by distracting attention from them, natural 

 selection will favour those animals which display this characteristic in the most 

 marked degree, but such actions could be harmful where there are eggs in the 

 nest, and being harmful would tend to be weeded out by natural selection, 

 other words natural selection would operate so as to preserve those indivi- 

 duals in which the mental balance is more easily upset after incubation than 

 during incubation. 



I would recommend all who are interested in this subject to read pages 

 59 to 66 of Bird Watching. 



Mr, Selous is of opinion that such actions were originally instinctive, but 

 he thinks that in certain instances, notably in the case of the wild duck, the 

 actions of the mother bird are blended with intelligence. He suggests that 

 natural selection has not only picked out those birds who best performed a 

 mechanical action which, though it sprang merely from mental disturbance, was 

 yet of a beneficial nature, but also those whose intelligence began after a 

 time to enable them to see whereto such action tended and thus consciously to 

 guide and improve it. 



This view appears plausible, but I do not think it is correct. It appears to 

 me to be both unnecessary and unlikely. Most of the actions of birds in 

 the vicinity of the nest, including nest building, are instinctive,* and it does 

 not seem probable that, in the midst of all these automatic actions, an exceed- 

 ingly intelligent act should be implanted. But the subject is a difficult one 

 and I have therefore no wish to attempt to lay down the law thereon. 



If any members of the Society have recorded observations which throw 

 light on the subject, I trust they will let the Society have the benefit of them. 



D. DEWAR. 



Lowestoft, England, 10th September 1908. 



This I have endeavoured to demonstrate in an article which appeared in The Albany 

 Review for Ansmst 1908. 



