in a semicircle around her head end , turning each time he gets 
on her flan*. This turning I inter ret as a sexual expression 
of preparing to mount. At first the turning doesn’t lead to 
raountWlng but the continued presence of the female in her typical 
pro* cooula tor y posture seems to provoke him sexually more and r.ore 
until it finally overcomes the last obstacle and after turning 
on her fls.nk for the last time he half-flies on to her back. 
Sometimes the male will not mount however much the female 
solicits him and at other times It is the other way round. 
Sometimes one can recognise that the reason that one of the 
partner’ does not proceed with the appropriate copulation oeh&vtou 
is because It experiences too great a tendency to attack or 
escape. Indeed one may see an actual attack on or avoidance of 
***** to be an intention 'iMwement of mounting the female* tut 
be «i so sometimes shows a number of bowing movements of his 
head in which the beak, which i® normally carried horizontal, 
is coin ted downwards and then returned to the horizontal. 1 
tried to discover what this bowing was due to. The movement 
slightly resembled one of the commons* t three t movements with 
which terns react to neighbours and sometimes > their mates. 
But ls movement mawt closely before 9 L w* anting at a time* 
when I did not expect the male to be aggressive. Another possib- 
ility was that it might be an altemv tlon of the intention 
movement of mounting with "imposture in which the m-. le stands on 
the back of 'the female after mounting. In this he looks down* 
wards at h*r head as he also does during the f.ct of copulation 
itself. However it turned out that it w? s more likely the 
aggressive movement, because man 1 looked at the pre-copulation 
behaviour of other specie a moat of them had the looking down 
of the mounted male and might be expected to show the alteration 
of this with the pre -copula lory neck stretohing, but non® o 
them had the bowing before mounting except the common tern, 
which was also the only on® to have aggressive bowing, fuia 
4 4'" W'AJf “ [, A* 4 J w '**• w W •- " , '" r ^ v -p > T^T 4* 
of a male oeoee tonal ly leads it. to attack a fafa^e. n tn^ 
rrey move towards an opponent or away from him or the posturing 
