CHAP. IX. SOCIABILITY OP BIRDS. 283 



litary bird. Heronries were formerly preserved in Eng- 

 land with great care, as the birds were esteemed royal 

 game. The passenger pigeons of America, whose ex- 

 traordinary migrations we have already detailed, perhaps 

 exceed all other birds in the extent of their societies, 

 and in the number of individuals which compose them. 

 The sociability of the swallow tribe, particularly during 

 the breeding season, is known to every one : in many 

 of the foreign species, the nests are so close together, 

 that they may be compared with more propriety to a 

 large house with innumerable chambers, than to a vil- 

 lage having distinct habitations. The hangnests of 

 America (Icterincs Sw.) form their dwellings in the 

 shape of long purses, suspending them so close to each 

 other, that we have frequently seen thirty upon a single 

 tree. The weaving birds of Africa (Ploceancs Sw.), as 

 we have elsewhere shown, do the same ; and most of 

 these tribes constantly live in permanent societies. 

 Aquatic birds, with few exceptions, are solitary, like 

 all such as live upon other creatures ; but the gulls and 

 the terns are exceptions, and they probably breed in 

 large communities. We know, by the relations of 

 voyagers, that the penguins are eminently social j and 

 that their breeding places are so crowded with nests, 

 that it is almost impossible to walk over the ground 

 without destroying either tbeir eggs or the young birds. 

 Numerous, however, as are these instances, they offer 

 no example of one common dwelling, like the hives of 

 bees, constructed by the united efforts of the whole 

 community ; for, in all the above instances, each pair 

 of birds provide their own materials, and build their 

 own habitation, and this is never larger than is ne- 

 cessary to contain their own young. It is curious to 

 observe how the social propensity is varied among the 

 feathered tribes. The starling, the redwing, and the 

 fieldfare are well known to be gregarious, at all times 

 except during the breeding season ; when each pair be- 

 comes solitary ; while the heron, and numerous other 

 birds, live by themselves, and only form societies when 



