The sea-eagle also builds on high rocks, according to Audubon, though Wilson describes the nest of one which he saw near Great Egg Harbor, in the top of a large yellow pine.  It was a vast pile of sticks, sods, sedge, grass, reeds, etc., five or six feet high by four broad, and with little or no concavity.  It had been used for many years, and he was told that the eagles made it a sort of home or lodging-place in all seasons.  This agrees with the description which Audubon gives of the nest of the bald eagle.  There is evidently a little confusion on both sides.

The eagle in all cases uses one nest, with more or less repair, for several years.  Many of our common birds do the same.  The birds may be divided, with respect to this and kindred points, into five general classes.  First, those that repair and appropriate the last year’s nest, as the wren, swallow, blue-bird, great-crested flycatcher, owls, eagles, fish-hawk, and a few others.  Secondly, those that build anew each season, though frequently rearing more than one brood in the same nest.  Of these, the phoebe-bird is a well-known example.  Thirdly, those that build a new nest for each brood, which includes by far the greatest number of species.  Fourthly, a limited number that make no nest of their own, but appropriate the abandoned nests of other birds.  Finally, those who use no nest at all, but deposit their eggs in the sand, which is the case with a large number of aquatic fowls.  Thus the common gull breeds in vast numbers on the sand bars or sand islands off the south coast of Long Island.  A little dent is made in the sand, the eggs are dropped, and the old birds go their way.  In due time the eggs are hatched by the warmth of the sun, and the little creatures shift for themselves.  In July countless numbers of them, of different ages and sizes, swarm upon these sandy wastes.  As the waves roll out, they rush down the beach, picking up a kind of sea gluten, and then hasten back to avoid the next breaker.

[Illustration]

BIRDS IN THEIR RELATION TO AGRICULTURE

(FROM THE PROCEEDINGS OF THE NEBRASKA ORNITHOLOGISTS’ UNION JANUARY, 1901.)[4]

BY LAURENCE BRUNER.

[4] By permission.

[Illustration]

When civilized man takes possession of new regions and begins cultivating the soil and establishes his sovereignty there, the equilibrium as it existed upon his arrival is very quickly disturbed.  One or more of the many forms of life—­plant and animal—­that were previously held within certain limits gain ascendency.  The introduction of new crops that furnish an abundance of the proper food for some insect, enables this form to increase out of all proportions and harm soon results.  The killing off of certain other forms of life that naturally keep still others in check also assists in disturbing the equilibrium further.  The cutting down and clearing away of forests removes the shelter