v THE PHILOSOPHY OF BIRDS' NESTS 115 



the nests were built comparatively open, so that the bird 

 within was not concealed. 1 The purple martin takes posses- 

 sion of empty gourds or small boxes, stuck up for its reception 

 in almost every village and farm in America ; and several 

 of the American wrens will also build in cigar boxes, with a 

 small hole cut in them, if placed in a suitable situation. The 

 orchard oriole of the United States offers us an excellent 

 example of a bird which modifies its nest according to circum- 

 stances. When built among firm and stiff branches the nest 

 is very shallow, but if, as is often the case, it is suspended 

 from the slender twigs of the weeping willow, it is made 

 much deeper, so that when swayed about violently by the 

 wind the young may not tumble out. It has been observed 

 also that the nests built in the warm Southern States are 

 much slighter and more open in texture than those in the 

 colder regions of the north. Our own house-sparrow equally 

 well adapts himself to circumstances. When he builds in 

 trees, as he, no doubt, always did originally, he constructs a 

 well-made domed nest, perfectly fitted to protect his young 

 ones ; but when he can find a convenient hole in a building or 

 among thatch, or in any well-sheltered place, he takes much 

 less trouble, and forms a very loosely-built nest. 



Professor Jeitteles of Vienna has described various forms of 

 nests of Hirundo urbica adapted to different situations, some 

 having the form of a semi-ellipsoid placed vertically, with the 

 entrance at one side, others being three-quarters of a sphere, 

 with the entrance in the centre. A nest of Hirundo rustica 

 was also observed supported on an iron hook in a wall, but 

 not itself touching the wall. It was quite hemispherical, like 

 that of a blackbird, a form common in England, whereas the 

 usual form on the Continent is that of a .quarter of a 

 sphere. 2 



The following case of a recent change of habit in nest- 

 building was communicated to me by Mr. Henry Reeks in 

 1870 : "Thirty years ago, and perhaps less, the herring-gulls 

 used to breed on some inland rocks in a large lake called 



1 Popular Science Monthly, vol. vi. p. 481. Quoted by Vice-President 

 E. S. Morse, in Address to American Association for Advancement of Science 

 at Buffalo, N.Y., August 1876. 



8 Ornithologischer Verein in Wien. Mitthelungen des Ausschusses, No. 3, 

 12 Juli 1876. See also Seebohm's British Birds, vol. ii. p. 174. 



