164 



HISTORY OF BIRDS. 



lows hide themselves in holes under ground, 

 joined close together, bill against bill, and feet 

 against feet. Some inform us, that they have 

 seen them taken out of the water, and even 

 from under the ice, in bunches, where they 

 are asserted to pass the winter, without mo- 

 tion. Reaumur, who particularly interested 

 himself in this inquiry, received several ac- 

 counts of bundles of swallows being thus found 

 in quarries, and under the water. 1 These 

 ~~ 



1 In the 51st vol. of the " Philosophical Transactions" 

 (for 1760), there is a letter addressed by Mr Collinson 

 in answer to the German naturalist Klein, who had ad- 

 vocated the opinion that swallows and other birds do not 

 migrate, but remain torpid during the winter. Subse- 

 quent naturalists have added little to the arguments and 

 facts which this letter brings against the opinion ; though 

 they have since been supported by collateral and nega- 

 tive testimony. 



The opinion that swallows at the time of their disap- 

 pearance retire under the water and remain there, says 

 this writer, is contrary to nature and reason ; for as 

 they cannot live in that state without some degree of 

 breathing, this requires the circulation of the blood 

 however weak and languid. Now as to respiration, is 

 it possible that it should be carried on for so many 

 months under the water without the risk of suffocation ? 

 If it were really the case, there must be some particular 

 contrivance in the structure of the organs of the heart to 

 enable it to undergo so remarkable a change of element; 

 but Klein had not even attempted to show that such a 

 peculiar organization existed. This remark of Collinson 

 probably led John Hunter to interest himself on the 

 subject. He states "that he had dissected several 

 swallows, hut found nothing in them different from 

 other birds as to the organs of respiration ;" and he 

 consequently concludes " that they could not remain 

 for any time under water without being drowned. 

 Collinson then asks why the opinion is never tested by 

 taking a swallow at a time when the species usually dis- 

 appear, and observing the result of confining it under 

 water in a tub for a week or two. Still proceeding with 

 his negative evidence, he states that towards the end of 

 September the swallows assemble among the reeds in 

 the islands of the Thames, and have done so for ages 

 past; yet he had never heard or read of any fishermen 

 or other person who had ever found a swallow under 

 water in a torpid state ; and if so strange a thing had 

 ever happened, it would doubtless have been communi- 

 cated to the public. Besides, the reeds and willows on 

 those islands are annually cut down for several uses, and 

 yet no swallow has been discovered in his aquatic abode ; 

 and considering the multitudes which might be seen on 

 these reeds and willows in the autumn, is it credible 

 that some should not have been found in so frequented 

 a river, during the course of so many years, if the swal- 

 lows really took up their residence under the water. He 

 adds that in great towns remote from water, where 

 rivers and reeds are not near, he had frequently observed, 

 a little before the swallows disappeared, that they assem- 

 bled every morning early on the roofs of large houses 

 exposed to the morning sun : this was doubtless in order 

 to collect their numbers before taking their flight. 



In the way of positive testimony for the migration cf 

 swallows, he says he had often heard Sir Charles Wager, 

 first lord of the Admiralty, relate, that in one of his 

 voyages home, in the spring of the year, as he came 

 into sounding in the channel, a great flock of swallows 

 came and settled on all his rigging ; every rope was 

 covered ; they hung on one another like a swarm oi 

 bees ; the deck was filled with them : they seemed almost 



men, therefore, have a right to some degree 

 of assent, and are not to lose all credit from 

 our ignorance of what they aver. 



All, however, that we have hitherto dis- 



pent and famished, and were only feathers and bones ; 

 hut being recruited with a night's rest, they took their 

 flight in the morning. Collinson adds that a similar 

 circumstance had been related to hjm by the captain of 

 a merchant vessel, on whose statements he could entirely 

 depend. Pennant remarks, on this incident, that the ex- 

 treme fatigue of the swallows proves that the journey 

 must have been very great, considering the amazing 

 swiftness of these birds. In all probability they had 

 crossed the Atlantic, and were returning from the shores 

 of Senegal or other parts of Africa ; so that this account, 

 from that most able and honest seaman, confirms the 

 following later information of M. Adanson, as adduced 

 hy Collinson himself, who considers the testimony the 

 more valuable, as coming from a professed naturalist, 

 who went to Africa for the express purpose of collecting 

 information. Adanson says, " On the sixth of the 

 same month (October), at half-past six in the evening, 

 being about fifty leagues from the coast (between the 

 island of Goree and Senegal) four swallows came to take 

 up their night's lodging on the ship, and alighted on the 

 shrouds. This lucky accident confirmed me in the 

 opinion I had formed, that these birds pass the seas to 

 get into the countries of the torrid /one at the approach 

 of winter in Europe ; and accordingly I have since 

 remarked that, they do not appear in Senegal but in that 

 season. A circumstance no less worthy of note is that 

 the swallows do not build nests as in Europe, but lie 

 every night by pairs, or single, in the sand upon the sea- 

 shore, where they rather choose to fix their habitation 

 than up in the country." To this quotation from Adan- 

 son, we may add another, relating to an observation 

 which he made on the subject at Senegal, in the month 

 of February: " The hut where I lodged was large and 

 commodious, but as dark as a subterraneous cavern, even 

 at noon day, because it had no other opening than a door 

 pierced at each end. Here I may observe that a great 

 number of our European swallows resort hither every 

 evening, and pass the night upon the rafters ; for, as I 

 have elsewhere mentioned, they do not build their nests 

 in this country, but only come to spend the winter." 



Collinson also informs us that he was anxious to test 

 the position of Klein that the sand-martins retire at tho 

 approach of winter into the holes in which they had re- 

 sided during the summer, and there remain in a dormant 

 state. But the sandy precipices in which these birds 

 build are generally so inaccessible, that some years had 

 passed before he could find a situation in which the ex- 

 periment might be made without difficulty or danger. 

 At last such a situation was found atByfleet, in Surrey, 

 and the clergyman of the parish, being his friend, and 

 well qualified to . assist in the experiment, under- 

 took it at his request. This clergyman in his communi- 

 cation states, that he took a square of about twelve feet, 

 over that part of the cliff where the holes were the thick- 

 est, which, in going down from the surface, would, as lie 

 judged, take in about forty holes. He set to work, and 

 came to the holes, but found no martins- nothing but 

 old nests at the inner extremity of the holes, which was 

 from a foot and a half to two feet from the entrance. 

 Forty holes were carefully searched without finding any 

 birds ; but thirty of them had nests, which were com- 

 posed of straws and grasses rudely put together, and 

 were sunk almost an inch arid a half below the level of 

 the passage. 



That the migrations of swallows and other birds should 

 ever have been doubted, can only be accounted for by 

 the fact that these migrations generally take place by 

 night, and in the higher regions of the atmosphere. An 



