Page:The British Warblers A History with Problems of Their Lives - 7 of 9.djvu/19

 by various species, and seeing a male highly excited whilst following in the wake of a female, we carefully note the extent of its territory with the intention of re-visiting the spot at a later date. A month passes by and in that same territory we find a nest containing well developed young. By removing one of them and allowing it to flutter about on the ground, we find that we thereby produce in the parent birds an excitement approaching in intensity that which we noted a few weeks previously. Now such uniformity of response can be observed with little difficulty. If a male behaves consistently in an extravagant manner in the presence of a female, we may look with some confidence for extravagance in its behaviour at the excited assemblies of the males, or in the behaviour of both sexes, when the nest or young are intruded upon. The Blackcap and the two Whitethroats are extravagant in their actions during sexual activity, whilst under the influence of parental emotion, or when excited at the presence of a neighbouring individual of the same species, and they may be said to represent the one extreme, i.e., the highest type of such behaviour; whilst the Reed and Sedge Warblers represent the other, the visible response being much less marked in their case. Between these two extremes ranges the motor expression of other members of the group. Approaching most nearly the degree of extravagance attained by the Blackcap or Whitethroat is the behaviour of the Grasshopper and Savi's Warbler, and perhaps on a level by itself is that of the Garden Warbler. Next in order we might place the reactions of the Chiff-chaff, Wood and Willow Warblers, leaving those of the Marsh Warbler midway between these three latter species and the comparatively unresponsive behaviour of the Reed Warbler. But in studying so elusive a subject as the emotions we have many difficulties to contend with, and the advisability of even attempting to allot a definite position in a hypothetical scale to this or to that species may be quite rightly called in question. The foregoing scale must consequently be regarded as an initial attempt