HYPOLAIS PALLIDA OPACA 111 



HYPOLAIS PALLIDA OPACA (Lichtenstein). 

 WESTERN OLIVACEOUS WAEBLER. 



Sylvia opaca, Licht. fide Cab. Mus. Bcin. i, p. 36 (1850). 



Hypolais opaca, Cah. Mas. Hein. i, p. 36 (1830) ; SeeboJim, Cat. Birds 



Brit. Mus. V, p. 83 ; Koeiiig, J. f. 0. 1892, p. 390. 

 Hypolais pallida, Malherhe, Fanne Ornith. de I'Alg. p. 13 (1855) ; 



WJiiial-ci; Ibis, 1895, p. 95. 

 Chloropeta pallida, Lochc, Expl. Sci. AJg. Ois. i, p. 271 (1867). 

 Hypolais pallida opaca, Erlangcr, J. f. 0. 1899, p. 251. 



Description. — Adult male, spriug, from Tunis, Nortli Tunisia. 



Above pale olive-brown, witb a faint yellowisli tinge on the back and 

 rump ; a faint bufTy-wbite stripe running from tbe base of the bill over the 

 eye ; entire underparts dull white, faintly washed witb buff, and grey on 

 the sides and flanks. 



Iris brown; bill yellowish-brown, becoming yellow on tbe lower 

 mandible ; feet pale brown. 



Total length 5-50 inches, wing 2-80, culraen -65, tarsus -90. 



Adult female similar to the male. 



The present species, which was included in my list of Tunisian 

 birds {Ibis, 1895, p. 95) under the name of H. pallida (H. and E.), 

 should no doubt be referred to H. paUida opaca (Licht.), a western 

 form of Hypolais, closely allied to H. pallida, but differing from it 

 sufBcientl}' perhaps to merit subspecific ranli. Tlie chief point of 

 difference between tlie two appears to be that of size, H. p. opaca, 

 the western form, being somewhat larger than H. pallida, the wing 

 measurement of the former averaging 2-80 inches while that of the 

 latter averages only 2'60 inches. The bill of H. p. opaca also is 

 said to be somewhat broader than that of H. pallida, and its 

 bastard primary rather longer than that of the latter species, but 

 I do not find these characters reliable. 



H. p. opaca is very common in Tunisia as a summer migrant, 

 arriving, as a rule, after the middle of April and leaving again in the 

 early autumn. I know of no instance of its wintering anywhere in 

 the Eegency. The species, throughout the spring and summer ' 

 months, is to be met with throughout Tunisia generally, both north 

 and south of the Atlas, wherever the environment happens to be 

 suitable. Well-watered localities are mostly frequented by these 

 birds, and the southern oases and tamarisk-bordered Gueds harbour 



