tralia and the United States than in Europe, because they left behind them their native enemies and their new enemies (crows, jays, shrikes, etc.) have not yet developed, to a sufficient extent, the habit of preying upon them. Nature will, perhaps, after a long time, restore the equilibrium destroyed by presumptuous man.
Protection of Birds.—1. Leave as many trees and bushes standing as possible. Plant trees, encourage bushes.
2. Do not keep a cat. A mouse trap is more useful than a cat. A tax should be imposed upon owners of cats.
3. Make a bird house and place on a pole; remove bark from pole that cats may not climb it, or put a broad band of tin around the pole.
4. Scatter food in winter. In dry regions and in hot weather keep a shallow tin vessel containing water on the roof of an outhouse, or out-of-the-way place for shy birds.
5. Do not wear feathers obtained by the killing of birds. What feathers are not so obtained?
6. Report all violators of laws for protection of birds.
7. Destroy English sparrows.
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Fig. 315.—Great Blue Heron. In flight, balancing with legs.
Migration.—Many birds, in fact most birds, migrate to warmer climates to spend the winter. Naturalists were once content to speak of the migration of birds as a wonderful instinct, and made no attempt to explain it. As birds have the warmest covering of all animals, the winter migration is not for the purpose of escaping the cold; it is probably to escape starvation, because in cold countries food is largely hidden by snow in winter. On the other hand, if the birds remained
