Immediately after their arrival in April the males begin their curious vocal performance, at first with a feeble and broken strain; but in a little while the voice gains in strength and shrillness, and the utterance becomes more sustained, lasting sometimes without a break for thirty or forty seconds, and even longer. This is renewed again and again at short intervals throughout the day, and continued far into the night. Indeed, the song may be heard all night long in fine summer weather. The sound is recognised by few of those who hear it as coming from a bird. It is usually attributed to an insect, and if the hearer grows curious, and tries to find the exact spot from which it issues, he finds this a somewhat difficult task. The sound seems now on this side, now on that, now far away, and anon close at hand; it is here, there, and everywhere. A good plan is to put the open hands behind the ear, then to turn slowly round until the exact spot is discovered. When the bush from which it proceeds has been found, the listener should advance cautiously to within a few yards of it, and sit down and wait until the hidden bird, recovering from his alarm, comes up to the summit and resumes his singing. It is then most interesting to observe him. The bird sits motionless, turning its head from side to side, and so long as the strain continues the yellow mouth is wide open, like the gaping mouth of a fledgeling waiting to receive food, the slender body trembling with the sound, as if an electric current were passing through it. The sound produced has been compared by different writers to the song of a grasshopper, only more sustained; to the cicada; to the whirring of a wool-spinner’s reel, and to that of a well-oiled fisherman’s reel made to run at a very rapid rate; and, finally, to the sharp, vibrating sound of the rattlesnake, and to an electric bell; but it is not so sharp as these last two. The grasshopper warbler builds on the ground, and so well concealed is the nest that it is only possible to find it by watching the birds when carrying nesting materials into the bush. The nest is formed of dry grass and moss, and lined with fine fibres. Five to seven eggs are laid, white or pale pink, spotted with reddish brown over the entire egg; and sometimes fine hair-like lines are mixed with the spots. * * * * * A small warbler, closely resembling the grasshopper warbler in its language and habits, and once an indigenous British species, is _Locustella luscinioïdes_, locally known as the reelbird, red night-reeler, and red craking night-wren, and in books as Savi’s warbler, after its discoverer. It bred regularly in the Norfolk Broads and the fen districts in Lincolnshire down to about 1849, when it became extinct. Hedge-Sparrow. Accentor modularis. [Illustration: FIG. 31.--HEDGE-SPARROW. ⅓ natural size.]