70 CONTROLLED NATURAL SELECTION 



carrying her in flight. In other species, the 

 pairs unite end to end ; in these cases, other 

 methods encouraging the taking of the male 

 are utilised, as will be shown later. But 

 although it seems that when thus united, an 

 enemy would chance to take male and female 

 equally, in many cases, owing to the position 

 in space occupied by the copulating pair, this 

 is not so ; for instance, in some cases the male 

 clings to a grass stem or other support, whilst 

 the female dangles below ; a bird taking such 

 a pair will strike first where the insect joins 

 the grass, having learnt by experience that 

 of insects, this, the head end, is the most 

 vulnerable part ; the bird will seize the male, 

 the female becoming unjoined will be likely 

 to escape. In such ways as this, by the 

 assumption of a particular position on the 

 part of the pair, will the taking of males rather 

 than females be encouraged. 



When copulating insects are given to birds, it has been 

 observed that when one has been seized, the other is 

 apparently mistaken by the bird for some foreign object, 

 which the bird endeavours to and does get rid of by 

 rapidly shaking its head : those insects which are firmly 

 joined together and only with difficulty parted will thus 

 be disconnected. 



The copulating habits of the Common 



