Itself normally*) In other wo Ha t*o hinds of displace™ at 
0 craping were at led. Scraping •Utah u nst 4^ 
of cemoat aotlvity hardly ever ©eours In S- ns th gfc It 
tE certainly dll so in the ancestor* and a till Ices in the related 
trails as well as la some groups of ttme. This ahovs once again 
how the no tiva tl on of behaviour my change In evolution. 
the a of laying art egg was few tiaes and 
I was specially interested to «•« how the brooding behaviour 
of the parents developed • The wsla at first was vary reluctant 
to sit and concentrated on feeding in* female * I*t®r ooth 
alternated in brooding the eggs. I ntvs not y&t worked 
out fully the proportion of tlmo spent brooding by each cox at 
the different nests* In one pair out of 3?3 Observations sad© 
throughout the lncubat . >S period at Inter? r t lea© than 
10 ©Irmtos the male- w&a sitting In 6*5* , But In the fi^flt tend ays 
sft«r hatching he sat only Vtf (11? observations}. As sent of the 
observation* on which these figures are based vern made between 
g a<rt r? |j it is not posoibie to -ooniude t tn t ■»■*,•> refleete 
th©"rc-l contribution of the ©ale towards brooding. It sight 
t>o the t ny <&&{#$ ct r® tbtc? result of & t# t^ii’Xofioy tov triAl® 
to brood wore in the mornings and tho female up re In the afternoons. 
At any rate it is possible to teat for regularities though. 
this is not yet completed. 
In tn*vt all the nests in a certain area of sand wore 
kept II sr o Ion to see when the clfcteb *%* & nd 
to study the success in rearing young. Some of the nests 
were washed away by a spring tide so there mre a tmuber of 
relayings but these could not 'tlstiiwtlehod from first .uiyings 
H to. lLvfclfcy of aoat of th. 3 «ir* «»• not »"«. oo clutch., 
were con: doted in all and showed the following f l~ tribute on of 
clutch sixes i 
l egg 
1 eggs 
3 egge 
• . 
I 
with & t soon vrlue of i *? o -?■ per clutch, "his figure the 
same ae the one arrived & t the previous y r by * *f ^ ' 
method. The Common tern lays a rather larger clutch o* two 
or three eggs. A few percent of the total number of .<esi© 
the -hole inner Fame ’tern colony contained thro® eggs end gone 
of these were genuine Arctics. I could distinguish them only 
by watching to non the speclos of th© parents* There were oven 
some Arctic nests with four eggs but in no case din * 
history, of the clutch. In none c* the cases I .w v,n... r obsenra tlcn 
could I be cur© tha t sore than on© female had l* s ~l - In n ccr -in 
r,c s te but fron the general laxity of territorial restrictions,, 
af espeelelly after th© spring tide had swept over mtch of t.ie 
boa ch , I should not be surprised if such a thing sore tines 
happened. In 3t nests the incubation period of the ories was 
