66 BIRDS OF THE DISTRICT OF GEELONG 
except the Pacific Gull ; which is so much larger than 
the Silver Gull that one could hardly be mistaken 
for the other, apart from great difference in plumage ; 
and the black cap of the Terns will enable the observer 
readily to distinguish a Silver Gull from any of these. 
BLACK-BACKED OR PACIFIC GULL 
Gabianus pacificus pacificus 
See a young bird of this Gull, with uniform dirty- 
brown plumage and horn-coloured bill (he is called 
Mollyhawk " when he is like that), and then look 
at an adult in his beautiful livery of black back and 
wings, spotless white head, neck, and under surface, 
and bright yellow bill : you will find it hard to believe 
that the two birds are not of different species. The 
brown plumage-phase is that more often seen, since 
the birds do not attain their full plumage until at 
least two years after they are hatched, as I learned 
by watching one kept in captivity. And it is quite 
easy to mistake the immature bird at a little distance 
for a hawk, so that one can understand the common 
name. 
In calm weather we do not see these birds very often 
on the Geelong foreshore ; they evidently prefer the 
other side, as it is only a very strong north wind 
that brings them over to hunt along the southern 
shore for such edible debris as may be thrown up 
on the beach. At such times they even pass a mile 
