COURTSHIP ACTIVITIES IN THE EED-THKOATED DIVER, 257 
2. A very remarkable ceremony, unfortunately only observed clearly on 
■one or two occasions, was the dive followed by vertical eniergence|(figs. 3 & 4). 
In the best-observed case two birds out of a party o£ three were close 
together. Suddenly one — almost certainly a female — dived (with a s[)lash). 
The other — almost certainly a male — immediately spread its wings and half 
flew, half sputtered along the surface of the water for 5 or 6 yards. The bird 
which had dived then came up out of the water close to the other, in an 
almost vertical position (fig. 3). The neck was held so as to continue the line 
of the body ; the head bent down so that the bill made a small angle with the 
breast. The emergence was fairly slow. It stayed in this position for perhaps 
5 seconds, then settled down on the water. Here we have a ceremony which 
is extremely similar to one which I have described in the Crested Grebe, 
although not quite so elaborate. Its chief feature of interest is that, although 
both birds play active parts in it (the flying-off and waiting of the non-diving 
bird is an active part, which culminates in the Grebe with a special dis[ila)'), 
yet the parts are different. If we may judge from the Grebe, either part 
Fig 4. 
Eed-thi'oated Diver : another sketch of an emergence ceremony. , 
may at different times be played by a bird of either sex. This is rendered 
more probable by the fact that the more active role on this occasion was 
apparently taken by a female. 
3. A ceremony in many ways resembling the Plesiosaurus race is also 
common, but apparently only among birds which have mated up. It is 
always accompanied by a cry which is the same as, or extremely similar to, 
the "roll-growl" already described. The two birds swim, one leading, for 
some distance with their necks arched so that the tip of the bill is submerged. 
The bill is also held open, in order to give the cry. The bodies, however, are 
not submerged posteriorly, but kept in normal swimming position, and there 
is not a marked wave thrown off the breast, nor does motion appear to be at 
all violent. As in the Plesiosaur race, the birds maj' turn, and the former 
leader become the second. This ceremony might be performed on the small 
nesting-pools or on the lagoon. Owing to the snaky look of the neck when 
in this attitude, I shall call this the snake-ceremony (fig. 2). 
There remain peculiar actions associated with coition ; these, however, may 
best be described later, in connection with the account of a particular pair. 
