BRITISH WARBLERS
imitated as far as it lay in my power to distinguish them, and the results plainly show a lack of any definite sequence. Two examples will suffice to illustrate my meaning. In the first case the imitations were produced in the following order: Sparrow, Blackbird, Whitethroat, Sedge Warbler, Sparrow, Whitethroat, Green Woodpecker, Blue Titmouse, Redstart, Blackbird, Whitethroat, Greenfinch, Swallow, Whitethroat, Blackbird, Swallow, Chiff-Chaff, Hedge Sparrow, Blue Titmouse, Swallow, Greenfinch, Sparrow, Greenfinch, Green Woodpecker, Blackbird, Sparrow, Whitethroat, Chaffinch, Starling, Thrush, Hedge Sparrow, Blue Titmouse, Whitethroat, Swallow, Sparrow, Thrush, Whitethroat, Hedge Sparrow, Blue Titmouse, Whitethroat, Greenfinch, Willow Warbler, Thrush, Hedge Sparrow, Green Woodpecker. And in the second as follows: Blue Titmouse, Swallow, Sparrow, Swallow, Blue Titmouse, Greenfinch, Blackbird, Willow Warbler, Sedge Warbler, Chaffinch, Pied Wagtail, Nightingale, Starling, Blue Titmouse, Sparrow, Redstart, Starling, Sedge Warbler, Sparrow, Swallow, Chaffinch, Whitethroat, Swallow, Starling, Greenfinch, Willow Warbler. There is nothing in the nature of a uniform sequence here; the most that can be said is that in certain instances imitations of the same two species are to be found in the same sequence. It must not be supposed that the above imitations were produced in a continuous stream unbroken by the true song of the species. Even when the bird is in an imitative vein it would, perhaps, be more correct to speak of imitations being intercalated among phrases of the song, than of phrases of the song being intercalated amongst extraneous imitations. Both the males were, singing in Worcestershire about 2.30 a.m., and whilst the imitations were being produced the majority of the birds copied uttered no sound within hearing; some would probably not have been astir at that hour of the morning. It is evident, therefore, that there is mental retention and revival of some kind; for it must be borne in mind that it is not only an alien note that
58
