COMMON LAPLAND LONGSPUR 1603 



The length of the incubation period appears to be generally the same 

 throughout the range, 10 to 13 days (Drury, 1961), 12 days (Wynne- 

 Edwards, 1952), 12 days (Sutton and Parmelee, 1955), 13 to 14 days 

 (Sutton, 1932). 



Young. — Nearly every author has commented on the early de- 

 parture of the longspur young from the nest: 9 days (Drury, 1961), 

 9 to 10 days (Wynne-Edwards, 1952), and 9 to 10 days (Sutton and 

 Parmelee, 1955). Watson's (1957) observations on Baffin Island 

 are generally appropriate for the species. He states that nestlings 

 showed a marked gradation in size, at some nests so great as to sug- 

 gest periods of hatching in excess of 2 days. This gradation was 

 evident in 8- to 10-day-old broods at the time of leaving the nest. 

 In at least four nests the smallest individual was left behind in the 

 nest and was apparently deserted and no longer fed for up to a day 

 after the others had gone. Two such young died, one in the nest and 

 one outside. Another that fluttered from the nest after most of a 

 day alone was not more than 7 days old and had all retrices and pri- 

 maries ensheathed. Most of the young left when 8 or 9 days of age, 

 when the retrices and primaries were just beginning to appear. About 

 the third week of July most of the young being fed by the adults were 

 unable to flutter more than a few yards and their tails scarcely showed. 

 Many seemed to have been deserted and dead young were often found. 



Wynne-Edwards (1952) suggests that the habit of leaving the nest 

 early may in part be directly correlated with increasing the clutch 

 size without increasing the size of the nest. 



Certainly towards the end the impression was given, both by the redpolls and 

 the longspurs, that the nest was ready to burst and I was prepared at once to 

 assume that dead chicks found in redpolls' nests had been suffocated. There is 

 moreover the growing danger of attracting the arctic weasel as the young become 

 daily noisier and as the odor of feces mounts. (The latter probably also attracts 

 the blowflies, whose larvae were found in all the examined nests of longspurs, snow 

 huntings, redpolls, and wheatears.) It is not difficult therefore to see advantages 

 in scattering the brood as early as possible, since it reduces the danger both from 

 predators and from overcrowding in the nest. But the parents are probably pre- 

 sented with a more difficult task in providing enough food for each of the young 

 after they are scattered, and the young are also deprived of the protection from 

 cold and wet, and in general the uniform environment which they have previously 

 enjoyed in the nest. It may be presumed that the advantages outweigh the 

 dangers, and that once the young have acquired sufficient control of body-tem- 

 perature their chances of survival are increased by dispersal. 



Two additional important points must not be overlooked: that the 

 frequent marked disparity in size of the nestlings can result in one or 

 more remaining in the nest only to be abandoned as Watson noted, 

 and that the chief predators of fledged longspurs are avian ones, 

 mainly jaegers, to which dispersed young are certainly more vul- 

 nerable than those in nests. 



