PARENTAL BEHAVIOR 



1271 



on her trips when she collects material 

 (great tit, Hinde, 1952; bullfinch, Nicolai, 

 1956) to collecting material, but not build- 

 ing (pied-billed grebe, Glover, 1953; Clark 

 nutcracker, Mewaldt, 1956). Observers of 

 some species have noted that the males show 

 all the elements of the nest-building behav- 

 ior in their courtship or other behavior, 

 without ever integrating them into effective 

 building (great reed warbler, Kluyver, 

 1955). Schantz (1937) observed a nest built 

 by a male song sparrow, a species in which 

 the nest is ordinarily built entirely by the 

 female (Nice, 1943). 



In some species of birds, the male may 

 play an important part in the selection of 

 the site, even when he does not participate 

 in nest-building (Hinde, 1952; Haartman, 

 1957). 



2. Correlations between Nest-building and 

 Other Behavior 



xA.s a first step in gaining some insight into 

 the relationship between nest-building be- 

 havior and the reproductive cycle, let us 

 consider how the occurrence of nest-build- 

 ing is related to other behavioral aspects of 

 the cycle. 



Copulation and nest-building. In a num- 

 ber of species, it has been reported that nest- 

 building begins at about the time when the 

 female becomes sexually receptive. The fe- 

 male snow bunting, after being vigorously 

 courted by the male over a 2 to 3 week 

 period, permits copulation for the first time 

 on the same day on which she first picks up 

 and carries nesting material (Tinbergen, 

 1939b). The female ruffed grouse, too, be- 

 comes sexually receptive the day she begins 

 to build a nest (Allen, 1934) . In both species, 

 the nest is built entirely by the female. Nest- 

 building and copulation may also begin at 

 the same time in species in which both sexes 

 build (house sparrow, Daanje, 1941; cedar 

 waxwing, Putnam, 1949; gulls, Paludan, 

 1951; Brewer's blackbird, Williams, 1952). 



Many observers have noted that, in vari- 

 ous species of birds, copulation is limited to 

 the nest-building period, which comes to an 

 end before the eggs are laid (tricolored red- 

 winged blackbird, Emlen, 1941; purple 

 martin, Allen and Nice, 1952) . This implies 

 that the eggs, some of which may be ovu- 



lated 8 or 10 days after the last copulation, 

 must be fertilized by spermatozoa held in 

 the oviduct for at least that time. Elder and 

 Weller (1954) found that domestic mallard 

 ducks could lay fertile eggs up to 17 days 

 after being isolated from drakes, and Riddle 

 and Behre (1921) report female ring doves 

 laying fertile eggs after up to 8 days of iso- 

 lation. Domestic hens may lay fertile eggs 

 after 20 or more days of isolation (Hart- 

 man, 1939) . 



It will be recalled that the male house 

 wren builds several nests before the arrival 

 of the female in spring, and that the female 

 finishes one of them some time after her 

 arrival. In this species, copulation is limited 

 to the period of female nest-building (Ken- 

 deigh, 1941). In the cliff swallow, another 

 species in which the male does a substantial 

 amount of nest-building before the pair is 

 established in spring, copulation between 

 members of the pair is not seen until the 

 nest is well under way (the mechanics of 

 copulation in this species are such that it 

 cannot be performed at the nest-site vmless 

 there is a partially built nest there) . How- 

 ever, promiscuous copulations not involving 

 the members of the forming pair may be 

 seen earlier, at the places where mud is be- 

 ing gathered for the nests (Emlen, 1954). 



Female white-crowned sparrows seem to 

 start building a few days before the first 

 copulations are observed (Blanchard, 1941). 

 In domestic canaries, the peak of copulatory 

 activity is normally slightly later than 

 that of nest-building activity. However, if 

 the partially built nest is removed each day, 

 so that no nest accumulates in the nest- 

 bowl, the peaks of copulation and of nest- 

 building activity occur at the same time. 

 This indicates that the peak of copulation 

 usually occurs later than that of nest-build- 

 ing behavior only because the presence of 

 the nest inhibits nest-building activity 

 (Hinde, 1958). 



Various elements of the nest-building be- 

 havior, such as the billing or carrying of 

 nesting material, are sometimes observed 

 as part of courtship activity early in the 

 season (Noble, Wurm and Schmidt, 1938; 

 Armstrong, 1947) . 



Most of the correlations discussed in the 

 foregoing paragraphs are derived from field 



