PLATE XVI 
THE USE OF POTHOLES IN TWO DEPTH CLASSES 
TWO SPECIES OF RIVER DUCKS AND TWO 
SPECIES OF DIVING DUCKS 
Mallard and Pintail 
BY 
NUMBER OF BROODS 


DATE 6/18 
WATER 
6/28 /8 T8 7/28 8/7 S/IT 
HEAVY HEAVY 
RAIN RAIN 
LEVEL /+—_——— FALLING —_—_}+-—_+— FALLING ——_ 
BZ 
FALLING 
POTHOLE TYPE A, and B, 
POTHOLE TYPE Ag 
POTHOLE TYPE Az 
ALL OTHER TYPES 
