-30-
than the southern birds.
skin.
This was not the case except for the
The ratios, south to north, of activity for the different
organs and tissues are as follows:
skin
«79
muscle
5.2
bone
lung
6.2
3.9
liver
5.3
kidney
4.8
tleum
6.1
The presence of more than six times as much activity in the in-
testinal tract of the southern island terns as that found in the
same organ of the northern island terns suggests that the southern
birds have access to a supply of food fish containing greater
amounts of radioactive material.
The higher level of activity in
the southern bird intestinal tracts 1s reflected in the greater
concentrations of radioactive material in the other internal
organs of the same animals.
In view of these observations it
probably would be advisable to
dmtain samples from Alinginae
Atoll, located seven and one-half nautical miles southwest of
Rongelap Atoll, since the Rongelap natives collect birds at
Alinginae as part of their food supply.
Tern eggs were collected at Kabelle July 16, December 8,
1954, and January 29, 1955.
The
levels of radioactivity in the
various parts of the eggs were low, with that of the shell epproximating the levels found in the bones of terns collected the same
day.
Radioactivity in the egg yolks varied from 13 to 3 times
that found in the muscles of birds in the same collections.
The
whites of the eggs contained the lowest amounts of radioactive
isotopes of all bird samples examined.
These
Evels were from
1/25 to 1/2 those found in bird muscle collected the same day.
ae
UNG.