3 
mi/ght be written as "keera-keera . . . " and "korr-korr- . . . " 
respectively. Oh yes, and the food begging call sounds very 
different though it has the same frequency, ^ixsamidaxaiiax 
Each syllable sounds more like "kye" rather than "kee". 
The Roseate's calls are in some cases very similar, 
» chlk" Instead of "jik", and "keeoo" instead of "kliu", but 
there is the addition of the Fish call ("chorik"). This call 
is not uttered in hostile situations, at least I hav^iever 
seen it in a fight. In this respect it seems to resemble what 
I sunoose to be the homologous calls of Sandwich and Caspian. 
The fish call in all these species seems to be uttered typically 
by a bird carrying a fish, perhaps especially (though not 
exclusively) by one who is unmated. It is very striking to 
w&Ach a Sandwich or Roseate hunting and see how when he suddenly 
catches a fish this call is switched on, and stops when he 
surrenders the fish. This call is also used in the 
aerial display byxbiafck (the High Flight) by both partners but 
especially, I believe, by the bent-role one. The call is used 
when bringing fish to the mate on the nest and also to the young, 
indeed when the young moves away from the nest it seems clearly 
to be by means of this cal I that the parent establishes the 
whereabouts of the young. In the Sandwich tern, and perhaps 
in the Roseate as well though I am less sure, the two birds 
who want to establish contact with one another, whether mates 
or parent and chick, call alternately in a very regular rhythm, 
a method which would sem to assist localisation of _ another olrd 
amid the hubuj? of a dense colony such as the Sandwiches form. 
So much for the situations when the fish call happens, 
the motivation I am at a loss and the other tern people 
any suggestions . They all seem agreed (and I too) that 
fish call, doesn't come in fights. By the way It is a 
giving the fish call which you have depicted in your thesis, and 
which you believed to be the homologue of the aggressive upright. 
There are two birds in the picture from which you took your 
As for 
haven' t 
the 
Sandwich 
drawing, the other one is actually calling with the head-tossing 
movement I mentioned in ray repprt on the gull and tern conference. 
I don't believe there is any hostility between these two. In 
my opinion the usefulness of talking about homologies or common 
origins ceases when one is considering postures such as this 
which have such a low degree of improbability. I would agree 
that this posture In the Sandwich might be homologous, in the 
sense that both it and the upright are ritualised 
forms of a stretching upward of the neck and a lifting out of 
the wings. But I have no reason to think that the S. Tern's 
stretching upward off* the neck is derived from an intention movement 
of attacking! In fact this sp. doesn't seem to attack from above 
at all but rather from a gekkering position. The stretching 
uoward of the neck seems to me to be moie likely a general alertness 
in the S.Tern. It Is for this reason that I don t like to 
use pure form in hoaologlsing movements unless the movements are 
■so improbable that they couldn't havearisen by chance convergence. 
It is in fact this reason that makes me search for homologues 
only among closely related species and only when the situations 
