10 



ordinarily complete their development in the same length of time, 

 yet if incubation did not begin till after the second egg was laid 

 the larger number of broods would hatch with no great difference 

 in age. As it is, very seldom do the eggs hatch within a short 

 period of time. This difference often becomes so marked that, 

 at the end of a week 's growth, the first one hatched will outweigh 

 the other by a fourth, or even third, of its own weight. In the 

 case of nests Nos. 29, 38, 43, 50, 61 and 90 (see table), where 

 the difference in age was not over 36 hours, the young weighed, 

 respectively, at the end of a week's growth: 49 and 29, 31 and 

 16, 53 and 29, 44 and 20, 38 and 20, 36 and 17 grms. 28 grms. = 

 1 oz.) These differences are, of course, exceptional, but by no 

 nieans rare. Even up to the third week there remains a notice- 

 able difference in size of birds from the same nest. 



The young are born blind and naked, except for a scant scat- 

 tering of down. Eyes open on the third or fourth day after hatch- 

 ing, yet sometimes development is delayed and they do not open 

 till the sixth or seventh day, and the young do not leave the nest 

 till they are over four weeks old. Examples of these retarded 

 cases Avere found in nests Nos. 17 and 84, w^here the young w^ere 

 in the nest fully four weeks after hatching. At the end of two 

 weeks, the normal young are able to fly a very little, and if forced, 

 to will even pick up food by themselves ; yet they do not leave the 

 nest until about a week later, and continue to be fed for some time 

 after. Just how long they are eared for in the wild state, it 

 Avould be difficult to determine, and may depend upon whether 

 or not the adults are to breed again that season. Unlike the do- 

 mestic pigeon, they do not lay a second time till the first brood 

 is entirely'' out of their way. From the second to the fourth week 

 the young grow and mature qutie rapidly, apparently more so 

 than during the first two weeks. Birds kept in the house gained, 

 respectively, from 31 and 34 grams to 65 and 67 grams during 

 the third week, and up to 95.5 and 96 grams during the next. 



The element of fear is developed early, appearing before the 

 end of the first week, while at the age of ten days, it bcomes so 

 acute as to drive the young bird from the nest when approached 

 too closely. This element of fear in all young birds is an ex- 

 tremely interesting ease of a latent instinct lying dormant till 

 necessity demands the function. The instinct lies undeveloped 

 in the young, tending to keep them in the nest against outside 



