Seattle, 5, 1956 
Dept, of Zoology- 
Dear Martin, 
Thanks for your letter of M a y 12. You sure saw something of gull 
behavior! Tell me: do you want your report back, or shall I sendit 
on to Mike and Esther? 
You must by now get a fairly good idea about the taxonomic rela- 
tionships in the group. One thing seems to me obvious: the large 
gulls form a very closely knit group, and the ridibundus-type is 
another one, with ptptoMon, rldibundus and novae-hollandiae very 
close together Indeed. \ 
It seems to me that w4 are approaching a stage in which one can 
see "primitive", original forms of display, one in this species, 
one in another. Thus you say that the alarm call of Belcher’s dull 
may be primitive. Your criterium is, I believe, that it is less 
different from the other calls than it is in most species. I got 
a similar idea as to the trumpeting call in the Glauvous-winged 
Gull: this is the only thing in which it differs from the Herring 
Gull; the single calls are all very much alike, and each is more 
drawn-out, and resembles closely the single keew-call as used 
for "Stlmmfuehlung" , just social contact. In the European Herring 
Gull, there are three phases, one a raw kaw, with in the oblique, 
then the throw-down or bend, with one or two smothered, hish-pitched 
calls, then the throw-back to the oblique with a series of keews 
beginning with a loud and high pithced one, and then the rest with 
diminishing loudness and descending pitch, thehead gradually doming 
forward and down. The Glaucous-winged rarely does phase 1, it does 
the bend with the first call, then throws the head back slowly, and 
gives a very equal, level series of Just rather long-drawn, no 
staccato keews. Because each is so similar to the general keew call 
this gives the impression of being closee to the original form. 
In all other displays and calls I can(t see nor hear any difference. 
Ecologically the species is more of an open sea fisher than our 
H.G., it does much more plunge-diving off shore. It has a dark eye, 
the wing tips are very light, a little darker than the blue mantle, 
and further the bird is a little stouter than our H.G. But after 
having se^n this I begin to wonder how the various HGs behave. I 
think a close study of those very closely related species of the 
HG superspecies may become very interesting indeed. 
I quite agree with your ideas about the redirected attack being 
primary in the grass pulling. I would be careful with the coining 
of the phrase "pseudo-displacement activities"; it Is quite possible 
that all d.a. are in this sense pseudo, the name d.a. ought, I think 
to be kept as a provisional, descriptive term, and its causation 
should be worked out, but as long as we have not done this in more 
cases, I think the coining of a new term would suggest a dichotomy 
which need not be there; the term wouod imply that you know that 
there are real d.a. as distinct from the paeudo, and that we don't 
know yet. But it is extremely interesting that the redirected attack 
which in rldibundus is just that, should develop into either feeding 
drinking or nest building in Belcher's. In our H.G. it certainly 
develops only in grass pulling. It is another example of the posslbi 
lity of finding the origin of a movement by comparative study, and 
then its radiation. One species may have the primitive form of one 
movement and another that of the other. Thus I believe that the 
Kittiwake shows a rather primitive form of choking, in which you 
can recognise the origin as throwing-down of nest material. 
