BIRDS 201 



vidual feathers of the spotted regions of both immature and adult birds 

 are pale slaty-gray basally ; toward the tip is an arrow head shaped 

 spot of dark brown with the apex directed toward the distal part of 

 the feather ; beyond this and forming the exposed margin of the feather 

 is a buffy-gray area. The youngest birds, represented by the olive 

 and yellow specimens of G. pallida have no brown spots on the 

 feathers of the lower parts. Our specimen is moulting. Hence, the 

 spotted phunage is obtained by a moult ittvolviftg a change in the 

 color of the feathers. The individual feathei^s of the adults that are 

 plain below and of those that are spotted below are the same in color, 

 but those that are unspotted are new, and show no signs of being 

 worn, while those of the spotted birds are so greatly worn that nearly 

 all the pale marginal part has been lost. Hence this difference in the 

 general coloration of the birds is not one of an actual difference in the 

 color of the feathers, but is a difference of the degree of abrasion of 

 the plumage. 



The immature spotted birds have the plumage very soft and lax, and 

 the tips of all the feathers are rough and ragged as if much worn away. 

 We have no specimens of this age having a fresh plumage, but it is 

 evident that if the feathers of the worn birds were entire the brown 

 spots below would be concealed, and then immature birds would 

 present the same two phases as do the adults. All of our immature 

 spotted birds are moulting so that between this stage and the adults a 

 moult intervenes. 



Hence there is in Geospiza pallida and G. heliobates no real color 

 difference between the males and the females. Immature birds in the 

 second plumage, /. e., in Stage H, differ from the adults only in having 

 the bill paler in coloration — brownish above and yellow below; in 

 the plumage being softer and more lax, and in possessing wider, more 

 distinct and more buffy wing bands formed of the pale edgings of the 

 middle and greater coverts. This latter character distinguishes birds 

 of this stage in all the subgenera and may be regarded, when com- 

 bined with a non-olivaceous plumage, as diagnostic of Stage II. 

 Hence between Stage II and the adults a moult intei-venes, but this 

 moult involves only a slight change in the color of the plumage. 



In its habits Geospiza heliobates is the most interesting species of 

 all the Geospizce. It inhabits exclusively the mangrove swamps and 

 feeds on insects. Whether it occurs on other islands besides Albemarle 

 and Narboro we do not know. These swamps in many places con- 

 sist merely of a narrow fringe of trees bordering shallow lagoons that 

 run inward from the shore; but in other places, such as at Turtle 



