210 BRITISH BIRDS WITH THEIR NESTS AND EGGS. 



Family - COL UMlilDsE. 



THE ROCK-DOVE. 



Colmnba livia, GiiELlN. 



THE Rock-Dove, or Blue-Rock of our fanciers and Pigeon shooters, is 

 undoubtedly one of the most familiar of all birds in its wild or domesticated 

 conditions. It is important to us as being unquestionably, without any intermixture 

 with other species, the origin of all our domesticated varieties of Pigeons. These, 

 as distinctly shown by Darwin, whose investigations into this species I had the 

 honour of assisting for many years, are capable of reverting to the precise colour- 

 ation of the plumage of the wild Rock-Dove, and, moreover, if a number of distinct 

 varieties are bred together, the mongrel progeny always shows a tendency to revert 

 to the original characters ; moreover, no allied species, such as the Stock-Dove or 

 the Wood- Pigeon, is capable of either being domesticated or of producing fertile 

 progeny with the Blue-Rock. The natural habit of the Rock-Dove is in the deep 

 caves and fissures which abound in many parts of our coasts, more particularly in 

 Scotland and Ireland, but the species has become so far domesticated as to breed 

 under any suitable conditions that it may find far inland ; semi-domesticated birds 

 often associating with those that are truly wild. The Blue-Rock extends through 

 Spain, Italy, Asia Minor to India. In that country, however, the local race which 

 prevails differs from that of Europe in having a blue croup or rump, whereas the 

 European wild birds have always a patch of white on the lower part of the back. 

 The Rock- Dove rears its young preferably in dark and gloomy caves iipon 

 the coast. The nests are merely a few stalks or straws laid on a shelf on the 

 rock. Two eggs are laid which require eighteen days for incubation, and the 

 young at first are exclusively fed with the curdy secretion previously mentioned. 

 Their growth is remarkably rapid, they being fed, after the first week, \?ith food 

 which is brought in the crops of the parents, but which is not, as usually stated, 

 semi-digested, inasmuch as it is thrown up by the old birds as soon as it is 

 collected, the crop having not the slightest digestive power, nor secreting any 

 digestive juice, this function being performed by the organ which is called the 

 proventriculus, a glandular secreting structure intervening betAveen the true crop 

 and the gizzard. It is needless to say that the Pigeons, being for the most part 



