The note of the Hoopoe is very remarkable, and not to be mistaken for that of any other bird with which I am acquainted. It sounds like the syllables “hoop-hoop,” “hoop-hoop,” frequently repeated, and in the quality of its tone approximates to the call of the Cuckoo, but the second note is a repetition of the first instead of being, as in the case of the Cuckoo, a third below it. Old authors affirmed that this peculiar sound was produced by the bird distending its cheeks with air, and tapping its bill upon the ground, thereby causing the notes to escape as it were spasmodically. This curious statement has received some confirmation from the observations of Mr. Swinhoe.[109] He says: “To produce these notes, the bird draws the air into its trachea, which puffs out on either side of the neck, and the end of the bill is tapped perpendicularly against a stone or the trunk of a tree, when the breath being forced down the tubular bill produces the correct sound.” He adds, however, that he has observed a Hoopoe perched upon a hanging rope, and uttering its well-known cry without any tapping of the bill. I cannot help thinking that a bird observed in the act of calling _whilst picking up food_, as many species do, has given rise to the notion that the sound is _produced_ by tapping, whereas in truth it precedes and follows the movement. The only motion that I could ever detect in a Hoopoe whilst calling was a nodding of the head, and a depression of the crest-feathers. From the accounts which have been handed down to us by old authors, and the numerous specimens which may be seen preserved in old collections, it would appear that the Hoopoe was formerly much more plentiful in England than it is at the present day. The decrease in its numbers probably arises from two causes, viz., the clearance of forest land, entailing the destruction of many old trees which were once attractive as nesting places,[110] and the increased use of fire-arms which unfortunately results in the destruction of many of these beautiful birds, at a time when they are just about to pair and commence nidification. The period of its migration into Europe in the spring sets in early in April. The late Commander Sperling, when stationed with his vessel in the Mediterranean, frequently met with Hoopoes at sea during their passage. In the English Channel on the 15th April, 1854, a Hoopoe after flying two or three times round a steamer entered one of the windows of the saloon and was taken, apparently exhausted with fatigue. Another, on the 21st April, alighted on a mackerel-boat between the Eddystone Lighthouse and Plymouth Breakwater, in an exhausted state, and allowed itself to be taken.