British Warblers and Accentors. 19 



The Reed- Warbler (Acrocephalus streperus). 

 The sexes are very similar in colouring. 



The Marsh-Warbler (Acrocephalus palustris). 

 Here again no sexual colour difference has been recorded. 



The Sedge-Warbler (Acrocephalus phragmitis). 



The hen is slightly duller than the cock, and the rump and upper 

 tail-coverts are less distinctly reddish. 



The Grasshopper Warbler (Locustella ncevia). 



The sexes are extremely similar, and no colour differences have 

 been noted. 



Savi's Warbler (Locustella luscinioides). 



No difference of plumage has been recorded in the sexes of this 

 bird. 



From the preceding observations it will be seen how important a 

 structural character is for discriminating between males and females 

 of the Warblers ; as a rule, the differences in plumage are so slight 

 that even the best observers have failed to recognise them. Then, 

 again, the summer and winter plumages and the colouring of adults 

 and nestlings differ more or less markedly from one another, so that 

 only by securing birds of the same age, and comparing them at the 

 same time of year, would it be possible to ascertain whether any 

 reliable difference actually existed. The best way to attain definite 

 results would be to accumulate skins of birds which have lived over 

 a year in captivity, the sex of which had been ascertained by careful 

 dissection after death, the date of the bird's decease being also 

 recorded on a label attached to it. 



The Accentors.* 



In my account of the Hedge Accentor in British Birds ivith their 

 Nests and Eggs, vol. i. p. 132, I have stated that the female has 

 the bill -slightly broader than the male. Recently, after examining 

 various Warblers at the Natural History Museum, I found that I 

 had no time left to look up the Accentors ; I therefore wrote to 

 Mr C. Chubb asking him if he could spare time to look into this 

 matter for me. He replied most kindly, as follows : — 



"I have compared seventeen females and twelve males of Accentor 

 modularis, and have come to the conclusion that the bill of the 

 female is slightly the longer, but the differences are so slight as to 

 be scarcely perceptible in measurement ; however, I found that the 

 length of the bill in the female varied from 5 to 07 inch, and in 

 the male from - 55 to 065. I also measured the width of the bill 

 at the nostrils, but could not distinguish any difference, 0"2 to 0-25 

 inch." 



* It is probable, if we could compare expanded wings, both of the Warblers and 

 Accentors, that they would afford more stable characters for separating the sexes 

 than the bills : I hope this may eventually be possible. 



