How to Study Birds 57
only infrequent, but the observations themselves are apt to be inconclu- sive or susceptible of more than one interpretation.
As an excellent species on which to conduct a series of observations during the mating season, the student is commended to the English Spar- row. What significance have its battles. struttings and general vociferous- ness when it is mating?
THE NEST
Probably less than twenty. possibly not more than ten, per cent of the eggs laid by birds bring forth chicks which reach maturity. So great, therefore, is the mortality among birds during nesting time that the continued existence of a species depends largely upon the degree of success with which it encounters the enemies of the young bird in the egg or in the nest.
It will add to our appreciation of birds' resources. and most assuredly to our sympathy with bird—life, if, before studying the nest and nesting habits of birds, we merely mention some of the enemies and dangers which threaten birds at this season. They are of two kinds: First. the elements; second, preda» tory animals, including parasites.
High winds, heavy rains. floods, hail-storms. excessive heat, are among the weather phenomena often fatal to the life of the nest: while. in this region, chief among the animals that prey upon birds” eggs. or young birds, are Crows. Jays, cats, squirrels, opossuins. minks. weasels, skunks. snakes, and man, who either directly. as an egg collector for the table or cabinet, or indirectly, in mowing fields or otherwise altering birds' nest- ing haunts, has more than won a prominent place among the enemies of the nest.
With such an array of adverse conditions and relentless foes the bird who lives to acquire the powers of adults of his kind may be said to have escaped ninevtenths of the dangers to which bird-flesh is heir. ()ne realizes. therefore, how important it is for birds to select a site. build a nest, and care for their young in a way which has proved to he most desirable for their species: and how readily lack of instinct or inability to conform to new conditions may mean failure to rear a brood and, in the end. extinction of their race.
The nature of a bird's nesting site appears to be determined by (i) the necessity for protection; (2) habit, whether arboreal. terrestrial or , . aquatic: (3) haunt, whether in woodland, field, marsh. etc.: belertmn . . . .
0/ a Site (4) temperament, whether social or solitary: (5) conditions of the young at birth.
Protection may be secured by hidingr the nest, by placing it in more
Mortalin 0f the N tasting Semen
Eliemiu 0f N erting Birth
Imparimire of Instinrt:
