5 
and the Arfctic s "keeyair" . Same situation, same form. 
As I have, told you in the conference report the food-begging 
of the terns xelbks a different form in the different species. 
Common and Arctic feaxaxfch® repeat the single syllable in 
a series while Roseate and Sandwich and Caspian utter single 
syllables at a time in a more gull-like manner. Incidentally 
this seems to be correlated with the amount of black on the 
face of the downy chicks. In the Arctic chicks where the 
bill is held open for several seconds at a time the black 
down frames the pink mouth. In the o 
fond begging calls are single there is less black. The black 
tern also haxx a sserles of food begging calls like the 
Arctic and Common. In my table I have linked together all 
food begging calls as homologous. Here my reasons are 
r&ther from the situation than from the form of the xxxixxxHfcH calls 
which show considerable variation not only in the amount of 
reduplication bit even in the form of each syllable. 
Some of the homologues in the Sandwich are not sure and 
in the Caspian even less so. I may have been rather Procrustean 
(to use your famous epithet) in building up my table but it may 
be some help to you. 
Note by the way that I have havered as to whether the 
ky2 call of the Arctic and Common should be considered as 
homologous with the Fish call of the other species or not. 
Because of the elaboration of this call the form is very different 
in the different species and ^because the situation of this 
call is wider in the A and C.^than in the others I -have not 
liked to use the other argument for equating it with the 
Fish call. 
I am not sure whether the information I have given so 
far will satis^ryour questions, so I will give you another list 
of the calls and displays provoked by intruders 
Away from colony Arctic terns may fly around and call keeyalr 
as they do to a human in colony, though less firecely. The 
same thing seems to happen in the Caspian tern (Bergman p.9). 
I n colony Human intruder provokes mainly "keeyair"as they 
bIMs hang overhead, also" jik" . Also towards hatching time 
especially the " ti^i tik-kyow" swooping attack. 
G-'ulls flying near colony provoke "kliu" calling, flying up and 
"tiki tik-kyow" attagk. Pigeons, which are much more feared than 
any other"preda tor"I have seen, evoke Panics accompanied 
sometimes by Jik calls, but for the main part silent. However 
some braver soul$ may dare to attack pigeons with" tiki tik-kyow" 
and these call frequent "jik" as they fly or perch nearby 
between attacks. Less powerful opponents, such as rabbits, 
often provoke" tiki tlk-kyow"a ttacks . Other terns may also, 
but usually they get the aggressive call ky2 if the bird is 
likely to attack, or the jik or keeyair if it isn't. Attacks 
may of course be perfectly silent. 
