784 



NATURE 



[June 17, 1922 



refers to the well-authenticated experiments of a Mr. 

 Bachmann with the American turkey-buzzard, another 

 carrion-eating vulture and one in which highly de- 

 veloped olfactory nerves had been demonstrated by 

 Owen. Portions of highly offensive offal were wrapped 

 in thin canvas : the birds seemed unable to detect the 

 food even when eating pieces of meat which were in 

 some cases strewn on the outside of the package, but 

 as soon as a small rent was made for them in the canvas 

 the prize was at once discovered. 



Both before and since Darwin's day the question of 

 the absence or presence of acute smelling powers in 

 birds has been much discussed, and the negative view 

 has-been maintained by many ornithologists of repute. 

 To this question Mr. J. H. Gurney now makes a welcome 

 and interesting contribution in a recent paper " On 

 the Sense of Smell Possessed by Birds " {Ihis, 1922, 

 Eleventh Series, iv, 225). After recounting the history 

 of the discussion and making reference to the anato- 

 mical facts and experimental findings, he deals at 

 length with the observational evidence in favour of 

 the existence of an acute sense of smell in certain 

 species. Among these the rook and some wood- 

 peckers are cited on account of the accuracy with 

 which they seem able to locate hidden grubs, below 

 the ground in one case and beneath the tree-bark 

 in the other. Various petrels are also mentioned, 

 some of these being credited by good observers with 

 the power, for instance, of detecting offal thrown over- 

 board by fishing boats even in thick mist. Geese and 

 ducks, too, have very frequently been thought to 

 possess powers of smell, and in the Norfolk duck- 

 decoys the watching decoyman customarily burns 

 peat or the like to prevent the birds scenting him 

 down-wind. Other birds, notably the great bustard, 

 commonly forsake their nests if their eggs have been 

 handled. The most striking case, however, is that of 

 the vultures of different kinds which are familiar in 

 many parts of the world. It is indeed difficult to 

 explain on any other theory than that of scent how 

 these birds of ill-omen should know when a death has 

 occurred in a house, congregating on the roof as if in 

 the hope of gaining access to the corpse which they 

 cannot possibly have seen : the same faculty was 

 traditional in this country as regards the raven, when 

 that species was commoner than it is now. Agaiijst 

 all this, however, there is a mass of testimony from 

 naturalists and sportsmen that birds show little or no 

 power of detecting the presence of an enemy, even if 

 approaching down-wind, until either sight or hearing 

 comes into play. The success with which bird photo- 

 graphers can conceal themselves close to birds' nests, 

 for instance, is in marked contrast to the difficulty 

 experienced in studying wild mammals. In the case 



of vultures, in particular, there is also the evidence of 

 the experiments already quoted, and the experience 

 of sportsmen in India that killed game is safe from 

 these birds if left covered from view. 



In view of the weakness of the evidence obtainable 

 by direct observation, due to the difficulty of eliminat- 

 ing the possible action of the other senses under 

 ordinary conditions, one would naturally look with 

 hope to experimental methods. These, however, 

 have not been altogether neglected, and the results 

 have been disappointingly inconclusive. Bachmann's 

 experiment, already quoted from Darwin, seems to be 

 one of the best on record. Another essay was Dr. 

 Alexander Hill's experiment (Nature, February 2,1905) 

 with domestic Turkeys, to which he offered alternative 

 dishes of the same food, one untainted and the other 

 containing some such substance as asafoetida, essence 

 of anise, or oil of lavender. The results were very un- 

 satisfactory, the birds appearing to be indifferent not 

 only to the smell but also to the taste of the noxious 

 substances. In America, Dr. R. M. Strong has tried 

 the effect of placing hidden food close to doves con- 

 fined in boxes which could be regulated to admit or to 

 exclude odouis. Here again the results were negative, 

 no notice being taken of the food by any of the birds. 

 To these may perhaps be added the experiment carried 

 out by Prof. Watson and Dr. Lashley on the noddy 

 and sooty terns of the Tortugas Islands off the coast 

 of Florida. These investigators were studying the 

 homing faculties of breeding terns, and in some cases 

 they tried the effect of sealing up the birds' nasal 

 chambers with wax : here again no difference in be- 

 haviour was observable. This last experiment is of 

 special interest because it had for its object the testing 

 of the theory that the olfactory apparatus may function 

 not as an organ of smell but as a mechanism for detect- 

 ing the temperature or humidity of the wind and thus 

 as an aid to directional guidance during prolonged 

 flight. 



There is, then, a well-developed olfactory apparatus 

 in birds which one is reluctant to consider altogether 

 ineffective, and there are instances of behaviour which 

 are difficult to explain except on the supposition that 

 an acute sense of smell exists in the species concerned. 

 On the other hand, there is a greater mass of evidence 

 of behaviour suggesting that the sense is not developed 

 to any important extent, and the results of experi- 

 ments — so far as they can be considered satisfactory 

 at all — point in the same direction. It accordingly 

 remains difficult to arrive at any definite judgment on 

 the question, and scepticism as to the existence of any 

 very efficient sense of smell in birds is probably still 

 warranted. As Mr. Gurney says, the onus probandi 

 rests with the upholders of the scenting theory. 



The Hull Meeting of 



IT is ninety-one years since the British Association 

 for the Advancement of Science was founded, in 

 Yorkshire, and it is sixty-nine years since the Association 

 paid its single visit to Kingston-on-HuU. One pro- 

 minent Hull citizen, the head of an important industry, 

 who was present at the Hull meeting as a member is 

 still living, but it is not anticipated that many others 

 will remember the previous Hull meeting. 



NO. 2746, VOL, 109] 



the British Association. 



By the appointment of a strong executive committee 

 and numerous sub-committees the arrangements for 

 the Hull meeting are well in hand, and it is hoped that 

 the attendance at Hull may exceed that at Edinburgh ; 

 everything possible is being done to attain that object. 



Situated on the broad estuary of the Humber, at 



the junction of the river Hull, King Edward I., so long 



j ago as 1299, saw the geographical advantages of the 



