BIRDS 



321 



black by the beginning of the breeding season, but the plumage does 

 not. The species nests at Tagus Cove in March. Several pairs of 

 mated birds were secured at this time, and many others observed, of 

 which the males were in immature plumage, some scarcely distin- 

 guishable from the females. In fact, the number of mated black billed 

 males in immature plumage nearly equalled the number of mated 

 males in black plumage. 



Adult Females. — We have three adult females taken in January, 

 one taken in February and three taken in March. The bills are not 

 as dark as in the males. The upper mandible is dusky or brownish- 

 black, while the lower is generally still paler. One of these females 

 is moulting; it is a March bird with entirely dark bill and was taken 

 mated with an adult male. 



Immature Females. — There are eight immatui'e females in the 

 collection, all taken in January. They have yellow or partly yellow 

 bills. The plumage in some is the same as that of the adult females, 

 but it varies from this to much paler, where the brown is not nearly 

 so conspicuous. Since no yellow-billed specimens were taken in 

 March, it appears that they acquire the dusky bill before this month, 

 probably in February. Nearly all of the young females are moulting, 

 but the new feathers are most numerous and conspicuous in the paler 

 plumaged birds. The absolute amount of brown color on the feathers 

 of the adult females and the darker immature ones is much greater 

 than on the feathers of the paler younger birds, so that the moult must 

 be accompanied by a change in the color of the feathers. 



Specimens from Narboro do not differ in the form of the bill from 

 those taken at Tagus Cove on Albemarle. The collection contains 

 four adult males in black plumage with black bills, taken in April 

 on the east side of the island. There are four males in black plu- 

 mage, taken in January on the north side of the island, that present 

 the following very unusual coloration of the bill for birds in black 

 plumage in January : the upper mandible in all four is brownish- 

 horn, in two the lower mandible is light horn-yellow with dusky tip ; 

 in the other two the lower mandible is mostly the color of the upper, 

 but is yellow at the base. These birds must either have been very late 

 in acquiring the black bills, or else precocious in attaining the black 

 plumage. One of these black, yellow-billed birds is moulting. 



There are seven specimens taken on Seymour and the adjoining 

 part of Indefatigable, during the last of April and the first of May. 

 One specimen is an adult male in purely black plumage and with a 

 black bill. Two are brown-backed males with much pale color on 



