1662 U.S. NATIONAL MUSEUM BULLETIN 23 7 pabt 3 



The many young calling conjointly produce the great noisiness so 

 characteristic of a heavily populated breeding ground. 



Both parents feed the nestlings, the female being at first the more 

 active and persistent. The food consists of various insects and 

 arachnids gathered both on and off territory. The males at this 

 time are somewhat less adamant in defense of their nesting territories, 

 and may forage together amicably in favored nearby areas — a sort 

 of no man's land among territories. Females still beg food, sometimes 

 successfully from males other than their mates, and then give it to 

 the young. Food begging at this time apparently has little or no 

 sexual function. 



The females frequently brood after feeding and during cold periods. 

 At one Baffin Island nest Watson writes: "The female was often seen 

 sitting on the young during the coldest few hours of the night till a 

 time when in one nest the oldest young was 12 days old, and the 

 youngest 8 days old and only three days from finally leaving this nest." 



Both parents tend to nest sanitation by carrying fecal sacs from the 

 nest. Shortly before the young leave the nest, their feces lose the 

 mucous sac and resemble adult feces. At this time the young also 

 develop a new and distinctive food cry which enables the parents to 

 find them more readily after they start to disperse. 



The brood may leave the nest en masse, but more often only part of 

 it leaves, followed by the rest considerably later. Some young may 

 leave the nest and even the nest crevice, and then return to it later. 

 This complex dispersal pattern makes it difficult to determine the dura- 

 tion of the fledging period. Watson found that the interval from 

 hatching until the individual left the nest for the last time varied from 

 10 to 17 days. Generally young buntings leave the nest proper before 

 they can fly well, though they may remain in the nest crevice for 

 another day or so. Some young fly strongly when 13-14 days old. 



Once outside the nest crevice the brood soon scatters, even beyond 

 the male's territorial boundaries. Those advanced young that dis- 

 perse early are largely or entirely cared for by the male parent, who 

 readily locates them through the food call. The remaining siblings 

 are probably tended by the female until parent-offspring relations 

 dissolve, for Tinbergen found fledglings fed by the same parent each 

 time. The young still flutter their wings and call noisily when begging 

 food. 



Territorial defense by the males now declines rapidly, singing be- 

 comes lax, and some males may start their prenuptial molt while 

 still feeding young. The fact that territorial defense declines at 

 fledging, a most critical time in the breeding cycle, has led some in- 

 vestigators to question the food function of the territory, though its 

 sexual function is widely held. 



