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when the whole mass, perhaps twenty feet wide and four feet deep, will break off and be 

 dashed to pieces at the foot of the crag. Such a catastrophe is a frequent result of the 

 passion the birds have for huddling their homes together ; and there is a possible moral 

 in it, looking towards a necessary check upon the enormous increase of a species other- 

 wise almost wholly safe from enemies or accident. 



" How each Swallow knows which of all those round holes, looking (to our eyes) so 

 exactly alike, is his own, is a marvel; yet no greater one, perhaps, than the wonderment 

 of the country boy at the readiness with which his city friend finds his own door among 

 the long blocks of uniform brown stone or marble fronts covering Murray Hill and the 

 region about Central Park. The Swallows seem to dwell at peace in their city, and 

 to be neighbourly, for it often happens that other species of Swallows will nestle close 

 by ; and in Dakota Dr. Coues saw them living in close proximity to Buzzards and 

 Ealcons, yet apparently on good terms with their powerful neighbours. Dr. Cooper 

 mentions, however, that in Montana the blue birds often 'jumped' Swallows' nests 

 and held possession successfully. The most remarkable instance of fraternity is related 

 by Mr. J. A. Allen, who saw them at Topeka, Kansas (where also they nested about 

 dwellings), ' frequenting the holes in the hanks of the Kaw River made by the Sand- 

 Martin, keeping in the company of those birds, entering their holes, and presenting the 

 same appearance of breeding in them as the Sand-Martins themselves.' Afterwards 

 Mr. Allen discovered them occupying niches of rock in Dakota. 



" So much for the manners of the Cliff or Republican Swallows, in their uncivilised 

 life. When white men invaded their wilderness, erecting houses and barns, these birds 

 were quick to perceive their availability, and the more knowing ones instantly abandoned 

 the always insecure rocks for the greater stability and protection of eaves and rafters ; 

 for which, indeed, they already had a sort of precedent in the practice of some Californian 

 colonies, which occupied now and then the trunks and branches of large trees (vide 

 Cooper) as building sites. This adoption of the new custom happened at once in all 

 parts of the country. There was no hesitation or experiment or doubt about the matter 

 at all. The first squatter was welcomed as an old friend by the Swallows, who instantly 

 made themselves at home on his premises ; the most venturesome pioneer in the Indian 

 country, and the remotest fur-trader among the lakes of British America, were each 

 cheered by the companionship of these affectionate feathered settlers. 



" The facility with which the Himndinidae adapt themselves to new circumstances 

 is proverbial. Changes in the architecture might therefore have been looked for here, 

 and are really to be found, all tending toward greater convenience and disjiensing with 

 useless labour. In building and repairing their nests they work with great diligence and 

 marvellous celerity. ' Where they exist in a large colony,' to quote the late Dr. Brewer, 

 'it is not an uncommon thing to see several birds at work upon the same nest — one bird, 

 apparently the female owner, always assisting and directing the whole.' When a pair 

 are at labour, they work in turn, first making a shelf upon which the workman stands 

 and builds out the nest from within, making the inside smooth, but leaving the outside 



