ROCK-DOVE. 349 



year ; some of its retreats being famed from remote 

 times for the numbers of Doves frequenting them. The 

 nest is placed on ledges, or in cracks and crannies in the 

 roof, or on any little prominence on the rugged sides of 

 the cave, whilst those on the cliffs are deep in the 

 fissures. It is a simple structure, rudely put together, 

 and made of dry grass, sea-weed, twigs, roots, or the dry 

 stems of weeds ; whilst grass in a green state has been 

 known to be used. The birds sit pretty closely, dashing 

 out of the caves and fissures in twos and threes as their 

 haunt is approached and explored, and flying right 

 away with no demonstration whatever. 



Range of egg colouration and measurement: 

 The eggs of the Rock-Dove are two in number, some- 

 what short and oval in form, and pure white. Average 

 measurement, r4 inch in length, by V2 inch in breadth. 

 Incubation, performed by both sexes, lasts from sixteen 

 to eighteen days. 



Diagnostic characters : The eggs of the Rock- 

 Dove are not easily confused with those of any other 

 species when taken direct from the nest, but otherwise 

 they cannot with certainty be distinguished from those 

 of the Ring-Dove, although they are usually smaller and 

 rounder. 



