354 Robbins, Cape Cod Pi-ping Plover. [ Jt j y 



seems to be as complete against a background of bare sand as 

 against one over which stones are thickly strewn. 



Of course it frequently happens that there is no time for con- 

 cealment. Then, the young birds attempt to escape by running, — 

 the tiny legs working with surprising rapidity and carrying them 

 over the ground so swiftly and smoothly that they looked like balls 

 of down blowing before the wind. Also, if their escape up the 

 beach is cut off and they continue to be closely pressed they do not 

 hesitate to take to the water. Even those only a few hours out 

 of the shell swim well and navigate their frail craft if not with 

 intelligence at least in a direction away from the source of danger. 

 Obviously neither of these two modes of escape can afford them 

 much security. 



The earliest concealing actions must be wholly instinctive, but 

 from them (which lead to a merely passive reliance upon conceal- 

 ment) there is a gradual transition to actions which are intelli- 

 gently directed to make the concealment more effective. For 

 instance, the very young when frightened run to a safe distance 

 and simply sit motionless. Birds a week or more older not only 

 run but usually hide; that is, they flatten themselves, head as 

 well as body, on the sand, often (perhaps in the majority of 

 instances) turning so as to face the danger point. Furthermore, 

 the older fledglings will repeat the performance as often as occasion 

 requires; a too near approach starts them running again and again 

 and the concealing actions will be gone through any number of 

 times. With those younger or less experienced there is as likely 

 as not to be no further effort made to escape after the first; and 

 this, as we have just seen, ends with no attempt toward conceal- 

 ment other than the negative one of sitting still. 



One of these newly hatched youngsters that we came upon 

 suffered his bill to be uptilted, his body to be prodded with the 

 finger and even permitted himself without protesting to be picked 

 up and held in the hand. All to no purpose; the machinery of 

 his nervous system seemed to have run down and when he was 

 returned to the ground he almost immediately settled into position 

 again. Evidently concealment, throughout the history of the 

 species, must have been generally successful; otherwise, it is hard 

 to understand why the relation between the concealing actions and 



