TERNS 
235 
One has only to watch a flock of terns feeding to recognize the appro- 
priateness of the popular term Sea Swallow. Their active grace and 
dainty, pearl-like colours are a joy to the nature lover. Terns are, on the 
whole, less maritime in their habits than gulls and are not so often seen far 
from land. They haunt harbours, shores, and beaches, and live largely 
upon small fish caught near the surface by quick, sudden dives from the 
wing, but they are not scavengers. In these dives the birds plunge in 
head first with a splash of white spray in which for a moment they dis- 
appear, but they never go far under water. 
03. Gull-billed Tern. 
Figure 345 
Gull-billed Tern; scale, 
la sterne hansel. Geochelidon nilolica. L, 14. About 
the same size and coloration as the Common Tern, 
but with a heavier and more gull-like black bill 
(Figure 345). 
Distinctions. East coast. Characteristic tern- 
like coloration but moderately forked tail. Com- 
paratively stout, gull-like bill and large legs and 
feet. Tarsus well over instead of under 1 inch. 
Hind toe well developed and half the length of the 
inner one instead of nearer a third as long. 
Distribution. Nearly cosmopolitan on warm 
temperate waters. There is one old record for the 
southern New Brunswick coast. 
69. Forster’s Tern, la sterne de forster. Sterna forsteri. L, 15 (Forking of 
tail 4- 1). 1 Plate XXVIII B. 
Distinctions. Central provinces. Forster’s Tern so nearly resembles both the Common 
and Arctic Terns as to require close attention to small details to differentiate it from them. 
The most determinative characteristic by 
which it may be separated from any 
other species is the coloration of the long 
outer tail feathers, which are shaded 
with dark on the inner instead of the 
outer web (Figure 346). The underparts 
are also pure white instead of being 
delicately shaded with pearly grey. In 
juvenility and autumn or winter plum- 
ages, the face markings are quite 
characteristic. In Forster’s Tern the 
dark face patch is sharply defined and 
does not overspread the nape to meet 
its fellow from the other side (Compare 
with Figure 347). In juvenile and 
winter plumages the bill is largely or 
completely black. 
Field Marks. In mixed flocks of 
Common and Forster’s Terns the latter 
can sometimes be distinguished by the 
superior silvery whiteness of the under- 
parts. The juvenile and autumn plumages are separable by the face mark being confined 
to the cheeks and not spreading across the back of the neck to make a dark nape band. 
The best criterion of the species in any plumage, however, is its call-note which is very 
different from that of the Common. Instead of a sharp “ Tearrrr ” it is a wooden and lower 
pitched “Churrrr. ,> When this difference is once heard and marked it affords the most 
reliable field guide that can be given. 
Nesting. On slight elevations in grassy marshes, in nests built of waste vegetation. 
Figure 346 
Specific details of Forster’s Tern; tail and head 
of juvenile or winter plumage; 
scale, \. 
1 This measurement shows the difference in length between the middle and outer tail feathers. A great part 
of the total length of these birds is in the greatly elongated outer tail feathery and these do not reach their maximum 
in juvenile birds. Hence this figure is given to correct the oftentimes greatly misleading nature of the usual length 
measurement. 
