80 USEFUL BIRDS. 
small Owls I have almost invariably found that the food 
consisted very largely of field mice and wood mice, with a 
few shrews, and rarely a bird or two. Several species of 
Hawks seem to feed almost entirely on field mice, small 
reptiles, batrachians, and insects. 
The young of Hawks and Owls remain a long time in the 
nest, and require a great quantity of food. They probably 
tax the resources of the parent birds excessively in the etfort 
to find enough food for them ; hence some species are forced 
to commit depredations on the poultry yard, while a few kill 
birds and poultry from choice. But most of these birds are, 
on the whole, useful to the farmer. Dr. Fisher, having ex- 
amined the contents of two thousand six hundred and ninety 
stomachs of Hawks and Owls from various parts of the United 
States, and collected the evidence of many observers, con- 
cludes that Owls are among the most beneficial of all birds ; 
and that Hawks, with possibly one or two exceptions, are in 
some degree beneficial to the farmer. 
THE VALUE OF WATER-BIRDS AND SHORE BIRDS. 
Many shore birds are to some extent insectivorous. Many 
Gulls and Terns might be reckoned among the friends of the 
farmer, were they fully protected by law and public senti- 
ment, as they now are in some countries and in some west- 
ern localities in our own country. But here they have been 
so persecuted that they usually keep well away from the 
vicinity of field and farm. Even as it is, however, they ren- 
der some service to man. Certain water-birds are useful to 
navigators, fishermen, and pilots. In thick summer weather 
the appearance of Terns or Gulls in numbers, or the sound 
of their clamorous voices, gives warning to the mariner that 
he is nearing the rocks on which they breed. Shore fisher- 
men enshrouded in fog can tell the direction of the islands 
on which the birds live by watching their undeviating flight 
homeward with food for their young. The keen senses of 
sea birds enable them to head direct for their nests, even in 
dense mist. Fishermen often discover schools of fish by 
watching the sea birds, that, like the larger fish, pursue the 
sinall fry. 
