138 BLACK-THROATED DIVER. 
the black on the throat is at first varied with some white 
feathers. 
The female is a little less than the male. 
In the bird’s first year, the head and neck on the back 
are grey; throat, white; back, deep brownish grey, margined 
with lighter grey. 
At the next moult the head and nape become purer grey, 
and some black feathers shew themselves on the hind part of 
the neck. The back becomes darker, and a few black feathers 
become apparent here also. 
The full plumage is not attained till the end of the thud 
year. 
