48 BIRDS OF SOUTH DAKOTA 
mon Crow. It has a black cap, white neck and belly, and gray 
wings and back. The dull orange bill changes to red during the 
mating season. No doubt this bird is rather rare and migratory 
in South Dakota, yet since most Terns and Gulls are similar in 
color and size one may sometimes be mistaken for the other. 
They may be distinguished in flight by the fact that the Tern 
usually carries its bill pointed downward while the Gull carries 
its bill pointed ahead in line with the body. Another distinguish- 
ing mark is that the Terns usually seen in our State have forked 
tails. 
Terns are not scavengers like the Gulls. Their food con- 
sists almost wholly of aquatic forms taken alive, part being larvae 
of insects injurious to the farmer, and the bulk of the rest small 
fish not useful to man. 
69. Forster’s TERN (Sterna forsteri.) 
This graceful bird is smaller than the Caspian Tern 
though similar in color, the tail feathers being darker. The tip of 
the orange bill is also dark. 
It comes to us in migration, when it may be seen sailing 
over lakes and rivers and darting into the water after small fish 
or insects. 
70. CoMMon TERN (Sterna hirundo.) 
This bird is rare even in migration in South Dakota. It 
is about the size of the last, except that the tail is shorter. Under 
parts dusky; back gray; crown black; bill orange tipped with 
black. 
74. Least Tern (Sterna antillarum.) 
As the name implies, this is the smallest of our Terns. 
It is reported as breeding in South Dakota. Forehead white 
with black crown; gray back, and white below. 
77. Brack TERN (Hydrochelidon nigra surinamensis.) 
This is preeminently our Tern. A common summer resi- 
dent, nesting in marshy places in the eastern part of the State, 
where it may be seen sailing gracefully over water and reeds, 
feeding on land and water insects, or frequently resting on wire 
fences that run through ponds and marshes. 
