Figure 3A. Dr. R.J. Hock places Geiger counter near nest of semi- 
palmated plover, whose eggs are camouflagedto resemble pebbles. 
= ee ———— 
SS SS 
Hours elapsed after release at 33 miles. 
Spa 2 
The 
cable is later buried and the 
box containing the recording 
meter is concealed. Figure 
3B shows record obtained 
with this mechanism. Fluc- 
tuating baseline shows natu- 
ral background radiation 
level, and the abrupt rise at 
21 hours and 29 minutes 
shows the precise moment of 
the bird's return. 
