B 
YERTEBRATA. 
YOUNG BAEN-OWL. (See page 6.) 
and rivers and continents for thousands of miles. The various modes in which these migra- 
tions are performed by different species are exceedingly curious. Some of them, as owls, butcher- 
birds, kingfishers, thrushes, fly-catchers, night-hawks, whippoorwills, &c., fly only at night, and 
others, as crows, wrens, pies, creepers, cross-bills, larks, bluebirds, swallows, &c., only in the day. 
Many move near the earth, while others soar beyond the reach of vision ; some go noiseless as 
the shadows; others proceed with all the noisy parade of a military march. Some — as our blue- 
bird, robin, blackbird, meadow-lark, cedar-bird, pewee, &c. — do not generally pass beyond the 
boundaries of our North American continent; they go only so far as may be necessary to find 
food, and consequently are the first to return with spring ; others — as the herons, plovers, swans, 
cranes, wild geese, &c. — are so impelled by the migratory instinct that they stop neither day 
nor night till they have reached their far southern homes. While most proceed wholly on their 
wings, there are some, as the coots and rails, that make a part of their long journey on foot, and 
others, as the guillemots, divers, and penguins, that make their voyage chiefly by dint of swim- 
ming! The young loons, bred in inland lakes and ponds, without the use of their wings, pursue 
their route by floundering from pond to pond at night until they reach some creek connected 
with the sea; upon this they fearlessly launch themselves, and finally work their way through 
storm and calm to the milder zone which they seek. These migrations, it may be observed, are 
chiefly confined to birds that are bred in temperate climates; but it appears that those which are 
natives of warm regions have a similar movement, though of less extent. 
In considering the senses of birds, we shall observe that Smell is generally less acute in them 
