(e) Young.—Look for the newly-hatched young about the last week in June, and describe their appearance. How soon after hatching do they leave the nest? Do they at once feed themselves, or are they fed by the parents? Keep the nest under observation after the young birds have left it, and notice whether the old birds rear another brood the same summer. In September look for the annual congregation of swallows which precedes their departure for Africa. 2. The house-martin.—Distinguish the house-martin from the swallow by the patch of white on the upper tail-coverts (Fig. 179), and by the feathered toes. Make notes of the dates of arrival and departure of the birds. Do house-martins occupy old nests or build fresh ones? What are the position, material, shape, and size of the nest? How does it differ from the swallow’s nest? Is the martin of sociable or solitary habits? Watch the birds building new nests or repairing old ones, and describe the process. Examine and count the pure-white eggs. What are the newly-hatched young like? How many broods have you known one pair of martins to rear in one season? Have you ever known martins to be turned out of their nests by sparrows? Watch for the autumn congregation. 3. The sand-martin.—Notice the small size of the bird, the mouse-colour of the upper parts, and the black feathers of the wings and tail. Note the dates of arrival and departure. Is the bird often seen near houses? Look for the nesting-holes in cliffs, banks, etc. Examine the holes, and notice that they lead into tunnels which slope slightly upwards. What is the use of the slope? If possible examine the nest at the end of the tunnel, and compare it and the eggs with those of the swallow and house-martin. Observe the peculiar jerky flight. Does the bird sing? Describe its voice. 4. The skylark.—Does the skylark frequent woods or open ground? Describe the appearance, size, and colouration of the bird, and try to see the long toes. Especially notice the long claw of the hind-toe. Have you ever seen the bird perching on trees or bushes? Are the feet [Pg 312] well adapted for perching? Does the skylark run or hop? In what month does it begin to sing? In March look for larks’ nests in hollows and ruts of fields. What are the materials of the nest? Describe the number and appearance of the eggs. Listen to the song, and try to say in what respects it differs from that of other birds. Does the bird sing only when flying, or also when on the ground? Describe the skylark’s flight, and study its method of soaring (p. 278). Observe that the birds collect into flocks in autumn. Do they leave the country for the winter? How do they spend the winter? Do they sing in winter? If possible examine the beak; for what kind of food do you think it best adapted?