18 FIELD-STUDIES OF RARER BIRDS 



Four eggs almost always constitute a first clutch, 

 though three only are sometimes laid. Five is fairly 

 usual with second broods : six I have yet to hear of. 

 More than anything else they resemble certain eggs 

 of the White throat, though even then they may 

 usually be distinguished by their smaller size and 

 greater elongation, as well as by a darker and con- 

 ciser pattern of markings. Some varieties to me 

 suggest a compromise between the Whitethroat's 

 egg and a certain type of that of the Reed-Warbler. 

 Their colour ranges from nearly white to pale 

 yellowish-white in ground, spotted and speckled 

 with brown of different shades, the inferior 

 markings being inky-grey. A correct identification 

 of the owners of any nest with eggs found later than 

 May 10th is imperative, since after that date the 

 Whitethroat's (this bird sometimes frequenting the 

 same type of ground) laying season is in full swing. 

 Of course any doubtful eggs though the nest 

 should always prove of assistance in the diagnosis 

 found in April may safely be attributed to the 

 Dartford Warbler. 



To the female falls the main onus of nest- 

 building and incubation, which lasts twelve or 

 thirteen days. Generally a close sitter, sometimes 

 is she a marvellously close one, even allowing you to 

 beat the bush containing her several times before 

 leaving her post. On other occasions, however, 

 the moment you get right up to the nest, on which, 

 if you know its exact whereabouts, you may per- 



