BRITISH WARBLERS 
Lesser Whitethroat, which, though having a helpless appeay- 
ance, does not exhibit so marked asign of adisabled limb. And 
if we are thus far agreed, our next step is to enquire whether 
any distinction can be drawn between these activities as 
a whole, and those which characterise the behaviour of a bird 
at other periods of excitement. 
Now I submit that this is an important point to decide, for 
it appears to me that the functional similarity is so marked 
as to warrant the belief that all the activities, occurring at 
different periods of excitement, can be referred to a common 
origin. If the movements of any of the more demonstrative 
species such as the Avocet, Reeve, or Kentish Plover, when 
their young are approached, are analysed, it will be found that 
all the curious ways in which the limbs and feathers are made 
use of, the flapping of the wings, spreading of the tail, raising 
of the back feathers, lying on the ground, &c., have their 
counterpart in the actions of various species during the period 
of sexual activity. ven the alternate expanding of the wings 
of the Kentish Plover, which at once arrests attention on 
account of the peculiar nature of the movement, is not con- 
fined solely to this period of excitement, the female Marsh 
Warbler (Acrocephalus palustris) behaving similarly during 
sexual excitation. No better instance of this striking 
similarity could, I think, be found than in the actions of 
the Reeve when her young are approached on the one hand, 
and those of the male Pied Wagtail during sexual excitation 
on the other. Both these birds, at the respective periods of 
excitement, raise the feathers on their backs, lower their heads, 
lower and spread their tails, and in a crouching attitude with 
drooping wings run about the ground. Anyone, in fact, who 
studies the Grasshopper Warbler, or Savi’s Warbler, or any 
of the more demonstrative species, during the period of sexual 
activity, cannot fail to notice, whenever the excitement reaches 
a certain degree of intensity, how great a similarity the 
resultant activities bear to those which occur amongst many 
species during the period in which the parental instinct is 
uppermost. 
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