198 THE STORY OF THE BIRDS 



always, save in the season of reproduction. 

 Some of the most solitary of these are the 

 Eagles and other Raptorial Birds. It is also 

 worthy of remark in connection with this pecu- 

 liar instinct, that some birds allow their broods 

 to keep in company with them almost up to 

 the time of the next breeding season ; but 

 others invariably disperse their family as soon 

 as the nestlings are able to forage for them- 

 selves. In a great many cases the brood and 

 parents migrate in company; in fact, grega- 

 rious and social tendencies are exceptionally 

 characteristic of migratory species. A plausible 

 explanation of these social and gregarious in- 

 stincts in birds may be that a greater amount 

 of safety is ensured by flocking together ; and 

 this seems confirmed by the fact that the most 

 solitary birds are either of large size or preda- 

 ceous habits birds well able to take care of 

 themselves. 



We will now pass on to a brief considera- 

 tion of Mimicry, Protective Colours, and Re- 

 semblances amongst Birds. These are subjects 

 which an entire volume would not be sufficient 

 to exhaust ; all that we can do is to give a few 

 of the most interesting facts. Take the subject 

 of Mimicry first, a fascinating study truly, and 



