4 BIRD LIFE ON ISLAND AND SHORE 
to reach the sea, it is often forced, like many 
another New Zealand river, for some consider- 
able distance to flow parallel to a banked beach, 
through whose loose shingle it percolates and 
filters. Not infrequently during heavy storms 
from the east, with even this escape blocked by 
high seas, the river waters are dammed back, 
and stored in a sort of reservoir or lagoon created 
by sand bar in front and dry land behind, such 
lagoon, however, always in the end breaking out, 
and the river again opening a fairly straight tem- 
porary gap. Normally the lagoon is daily filled 
and emptied by tides that pass up and down the 
tortuous, indefinite, ever-shifting, shallow course 
of the stream. On either side of the river mouth 
extend for miles narrow coast lines of sand and 
shingle. 
Southwards there is no possibility of danger 
from floods and heavy seas, southwards there is 
no paucity of stony steppes, southwards there are 
no drifting dunes to harm the sitting birds. The 
southern side of the river is, however—and this 
outweighs all these beatitudes,—easy oi access 
from the village and native pah. On the northern 
side, contrarywise, conditions are dangerous to 
avian life from occasional floodings of the lagoon, 
and from occasional over-toppings of the beach 
by heavy seas. It is nevertheless the north side 
of the river that has been chosen for nidification, 
