106 CORMORANTS AND THE GIPPSLAND LAKES FISHERY 
It is possible that the fifth species, the Black^faced Pied 
(Phalacrocorax fuscescens (Vieill.)) occurs as an occasional 
visitor, but so far no specimen has been taken. 
It was obvious from the beginning that only the Large 
Black and Small Pied were likely to be of any importance 
to the work in hand, the other two being too few in numbers 
to warrant consideration. Soon after the examination of 
stomach contents was commenced it became apparent that 
the Small Pied also was of no consequence in so far as edible 
or marketed fishes were concerned. Thus the collecting and 
examination of the Large Black Cormorant received most 
attention and no other species is included in the results that 
follow. 
It is necessary to make clear that the Cormorant popula- 
tions on the lakes are not permanent throughout the year. 
The first record of any species nesting in the area was made 
in 1939 when, I am informed, a small rookery of Yellow-faced 
Pied was discovered. All other species apparently leave the 
lakes for breeding, and therefore are present in considerable 
numbers during only a part of the year. 
For the purpose of this investigation I should like to have 
obtained about 25-30 specimens of the Large Black Cormorant 
per month throughout the year. This number would have 
given a very good cross-section of the food, and it is what 
was aimed at but not quite attained. However, more than 
200 stomachs of the Large Black alone were examined, and 
practically all were collected during the six months when the 
birds are most numerous on the lakes. During the three months 
November, December, January, when no specimens were 
obtained, the number of these birds on the lakes must be 
negligible. 
The volumetric or percentage by bulk method is employed 
here to record the stomach contents. This involves the 
deterruination and sorting out into separate masses of the 
different species of organisms present in any one stomach. 
This completed, the smallest mass is taken as a unit and from 
it the volume percentage of each species of organism is 
determined. It is the method adopted by the majority of 
workers, and has been used consistently by the Bureau of 
Biological Survey of the United States Department of Agri- 
culture, the work of which, both in amount and execution, is 
outstanding. 
A few workers, including D. L. Serventy in a recent paper 
(The Emu, xxxviii, 1938, pp. 293-316) use the numerical 
