1618 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



Clutches of four or more eggs take between 24 and 48 hours to 

 hatch, and may take as long as 72 hours. While I have no definite 

 evidence of longer hatching periods, a few of the nest histories from 

 Cape Thompson suggest that it could have run to a maximum of 

 96 hours. Only one nest with 4 eggs was observed to hatch com- 

 pletely in 24 hours. 



Young. — The most striking single feature in the development of 

 young longspurs is their early departure from the nest, well before 

 the plumage develops enough to permit flight. 



My records from Cape Thompson show that most young leave the 

 next after 8 to 10 days, with an average nest life of 9 days. A few 

 histories show departure as early as the 7th day and as late as the 

 11th. The young left two nests in 6 days, probably because the 

 nests were disturbed. W. J. Maher (1964) reported the nestling 

 period at Barrow, Alaska, averaged 7.4 days with a range of 6 to 8 

 days. This relatively brief time was undoubtedly influenced some- 

 what by nest disturbance. Maher reported that the average weight of 

 longspurs at hatching is 2.3 gm. and increases to 18.8 gm. 7 days later. 

 When the longspur is able to fly on about the 12th day it averages 

 about 21.9 gm. or 80.5 per cent of its adult weight. Maher noted that 

 the gaping response is weak on the day of hatching and grasping with 

 the feet appears on the 2nd day. The fear response of huddling 

 down in the nest appeared on the 5th day and escape was attempted 

 by the 7th day. 



My records show that the young usually leave the nest over a two- 

 day period, although in some instances all young left the nest within 24 

 hours. In one case the departure of sLx young apparently spanned 3 to 

 4 days. It is not uncommon for one young bird to remain in the nest 

 a day or two longer than his nestmates, especially in the larger broods. 

 This might be due to later hatching and/or to difficulty in getting a 

 proportionate share of the food, for disparity in nestling size is com- 

 monplace. 



The sexes share equally in the feeding of the young birds. After 

 leaving the nest the brood is often split and each adult cares for a 

 portion of the young. Maher (1964) inclosed nests with a fence and 

 observed that the young begin to fly on the 12th day. At Cape 

 Thompson fledging success was 1.68 young per pah- of adults in 38 

 nests in 1960 and 1.9 in 53 nests in 1961. 



Density. — The following figures may bear out the belief expressed 

 earlier that the Lapland longspur is very likely the most numerous 

 bird in the north. At Cape Thompson the density per 100 acres was 

 14 pairs in low riparian willows, and up to 59 and 65 pairs in the 

 widespread plant formations of Eriophorum tussocks and Carex 

 meadow. Extrapolating these figures for larger areas of generally 



