Teeters, Nods, and Bobs 



M ^S+ INTEREST IN THE ACTIONS OF BIRDS 



and mammals is not always proportional to the importance 

 of those actions. Frequently it is based on simple curiosity 

 because the purposes are not easily explained. I suppose that 

 it is really not imperative to know why birds engage in those 

 regular spasmodic or jerky movements known as teetering, 

 nodding, bobbing, or dipping. I suspect that if the move- 

 ments were explainable the solution would be of no direct 

 benefit to mankind, and that if I would mention it to our 

 somewhat blase youths they would merely answer with two 

 pungent words, "So what?" But personally I never see an 

 otherwise normal-appearing bird begin to teeter, bob, dip, 

 or jerk, without wondering why such mechanism should be 

 built into an animal. I have always wanted to know why 

 these apparently useless and nerve-exhausting habits belong 

 to many species of birds and are as much a characteristic of 

 that species as their color, the length of their bills, or their 

 internal structure. 



I have heard many people speculate on the cause of these 

 movements. I suspect that much of the interest is due to the 

 theory that among people such twitches, involuntary move- 



187 



