350 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



season grasshoppers become conspicuous in the diet. The adults 

 dig up both cutworms and earthworms. 



The male shows solicitude for the nest and its contents for the 

 first time after the hatching of the eggs. His solicitude is restricted 

 to calls. The female will leave her brooding in typical concealment 

 by abandoimaent when conditions are appropriate as when incubating ; 

 likewise she will go from the young in distress simulation under con- 

 ditions as noted previously. Proportionately the number of conceal- 

 ments by abandonment decreases and distress simulations increase 

 slightly with young in the nest. Other reactions, which are various 

 primitive expressions of solicitude, or intennediates of the two 

 just mentioned, increase proportionately. Perhaps a return of more 

 primitive instincts indicates a sum total of greater solicitude. Since 

 the female is frequently absent from the nest in food foraging, she 

 will come in, as an intruder approaches, with calls and cries. One 

 or two references in the literature show that the reactions to dogs 

 is the same as to man, but that hens are driven off by entirely differ- 

 ent methods. 



The larks removed all excreta throughout the full extent of nest 

 occupancy. Early in the season much of the excreta was eaten by 

 the adults ; later it was dropped to the ground 50 or more feet away. 

 This seasonal change of habit may have been related to the available 

 food supply. The instinct compelling excreta removal proved itself 

 very powerful, at times overcoming strong solicitude for nestlings 

 and even fear. 



The young showed a psychic development closely related to their 

 rate of growth and not to their age. Young of the same age or but 

 one day younger than their nest mates often presented a psychic 

 development two to four days behind them. This was due to uneven 

 feeding, which occurred frequently early in spring because of uneven 

 hatching or an inadequate food supply. 



Normal nestlings give a food response indiscriminately up to the 

 fifth or sixth day. Just prior to this time their eyes open. Follow- 

 ing this they respond not at all or momentarily only. They withdraw 

 at a touch from the hand on the sixth day and sink back quietly into 

 the nest in crouch-concealment between the seventh and ninth days. 

 Upon being removed from the nest at this age they sit quietly upon 

 any object upon which they are placed ; prior to this time they wriggle 

 about when taken from the nest. They leave the nest on the tenth 

 day and then express fear by hopping and calling wildly when dis- 

 turbed. An expression of this type of fear, prior to the tenth day, 

 would take them from the nest prematurely. 



Weight-growth curves show a gradual increase over the first three 

 days, a very precipitate rise (except for April nestlings) for the next 



