406 DIVISION I. VERTEBRAL ANIMALS. — CLASS II. AVES. 



construct a roof of interwoven grasses, )jcneatli wliich tliey arrange their 

 individual nests. C^ne of these cuniniunities is tliiis described: — 



" The industrv of tiicse hirds seems ahnost equal to that of the bee. 

 Thmu'diiiut the day they appear busily employed in carrying a tine speciea 

 of grass, wiiich is the principal material they employ for the purpose of 

 ercctin"' this extraordinary work, as well as f(jr additions and repairs. 

 When the tree that is tlie support of liiis aerial city is obliged to give way 

 to tb.c increase of weigiit, it is obvious that they are no longer protected, and 

 are under the necessity of building in other trees. One of these deserted 

 nests I had the curiosity to break down, to inform myself of the internal 

 structure of it, and found it eipiaiiy ingenious with that of the external. 

 There arc many entrances, each of which forms a regular street, witli nests 

 on botli sides, at about two inches distance from each other. The grass with 

 wliich they build is called the I>oshnian's grass, and I believe the seed of it 

 to be tlicir princi[)al foml, thougli on examining their nests I found the 

 wind's and legs of dilferent insects. From every appearance, the nest 

 wliicii I dissected had been inhabited for many years, and some parts were 

 much mure (•(]m[iiftc tlian (itliers. Tiiis I conceive to amount nearly to a 

 jiroof tliat the birds added to it at diU'erent times, as tiiey found it necessary 

 from tlie increase of their family, or ratlicr of the nation and community." 



Another writer saj's, — 



" \\'lien a nestling-place has been selected, and the operation of building 

 the nests is to be commenced ah initio, tiie community immediately proceed 

 conjointly to construct the general covering wliich interests tlicin all ; that 

 being accomplislicd, cadi pair begins to iiirm their own nest, whicii, like 

 tlie roof, tiiey construct of coarse grass ; these are placed side by side 

 against flie under surface of the general covering, and, by the time they are 

 all completed, the lnwer surface of the mass exhibits the appearance of an 

 even horizontal surface, freely [lerfcjrated liy small circular openings. 



"Tliey never use the same nests a second time, thougli they continue for 

 many years attached to the same roof. A\'itii the return of the breeding 

 season, fresh nests arc formed ujioii the lower surface of iIkjsc of the pre- 

 ceding year, wliich then form an addition to the general covering. In this 

 manner they proceed year after year, adding to the mass, till at last the 

 weight often iiccomes such as to cause the destruction of its support ; upon 

 whicli a new building-place is selected. Tiiey ajipcar to prefer constructing 

 these nests upon large and lofty trees ; the commencement of the roof is 

 firmly intcrwo\en witii the brancjics of the tree to which it is intended to be 

 suspended, and often a great part of a principal branch is actually included 

 within its substance." 



