start its song just as it leaves a tree, and however long its flight may be (it is never of any great length), it maintains throughout it the slower opening phrases of the song, saving up the rapid concluding trill until the moment of its alighting in the second tree.
The most remarkable instance of a bird's singing on the wing that has come under the writer's notice was one furnished by a Chiffchaff. The bird was chasing another, presumably the female, on the outskirts of a wood; the two were flying at an incredible speed close to the ground and near a hedgerow, the pursued making sudden turns and twists, which were followed closely and with perfect precision by the pursuer; and one of them, probably the pursuer, was repeatedly uttering the clear "chip, chop" almost as placidly as though he were singing from his accustomed tree-top. It may be remarked in passing that the powers of flight held in reserve by these smaller Warblers are extraordinary. This fact is occasionally illustrated in a most surprising manner by the Willow-Wren. Just after their arrival in the spring (possibly when only the males are about). Willow- Wrens are exceedingly pugnacious, and one may sometimes be seen to take up a position on a post, or in the lower branches of a tree, and from there to make fierce sallies upon any bird not larger than a Finch that happens to be flying by; it will always take especial pleasure in attacking a Sand-Martin—indeed, the Sand-Martin seems to be a common butt for any small bird's exuberance of spirits; and in every case the Willow-Wren will exhibit on the wing a command both of speed and agility which is in the greatest possible contrast with what one would expect from the everyday deportment of its life. It is a sight that in a measure prepares one's mind for the startling conclusions reached by Gätke, and makes it a little easier to understand how such small and delicate birds as these can conduct with so much speed and success their long migrations overseas.
The slight revival of song that takes place in the autumn has often been remarked upon. The most conspicuous part in it is taken by the Chaffinch, Yellowhammer, Willow-Wren, and Chiffchaff; the Lesser Whitethroat also sings a good deal in early autumn, but omits the string of loud notes that form the ending
