PARENTAL BEHAVIOR 



1281 



Whitman (1919) found that various spe- 

 cies of doves and pigeons would not ovu- 

 hite unless nesting material and nesting lo- 

 cations were provided. Lehrman, Brody 

 and Wortis (1961) found that the presence 

 of nesting material plays a significant role 

 in the stinmlation of ovulation. Female 

 ring doves kept with males in cages not 

 sui)plied with a nest bowl or nesting ma- 

 terial will not ovulate as soon or in as high 

 a percentage of the cases as will such fe- 

 males kept in cages with males and an ade- 

 (luate supply of nesting material (the inci- 

 dence of ovulations after 6 days in the cage 

 is 55 per cent without nesting material, 95 

 l)er cent with nesting material) . Differences 

 in oviduct weight (and in frequency of ovu- 

 lation) between the groups of birds with 

 and without nesting material in the cage do 

 not become apparent until some 5 or 6 days 

 after the birds are placed in the cages, al- 

 though, as reported above, increases in ovi- 

 duct weight as a result of association or 

 nonassociation with a male are to be seen 

 within less than 48 hours. Since male doves 

 collect most of the nesting material, while 

 the females build most of it into the nest, 

 and since no oviduct development is stimu- 

 lated by nesting material in the absence of 

 the male, it seems likely that the courtship 

 behavior of the male ring dove which is not 

 yet interested in nesting material causes 

 estrogen secretion {i.e., FSH secretion by 

 the pituitary gland of the female), whereas 

 nesting material (or the behavior of the 

 male which has nesting material available) 

 later facilitates the secretion of progesterone 

 (I.e., LH secretion by the female's pituitary 

 gland). We may recall that progesterone 

 induces both the final ovulatory pulse of 

 LH from the hypophysis, and the histologic 

 changes in the oviduct which occur after the 

 albumen-secreting glands have been formed 

 under the influence of estrogen. 



From the above data, it is clear that in 

 some species in which the male participates 

 in nest-building, the presence of nesting ma- 

 terial and/or the change in behavior of the 

 male which is made possible by the presence 

 of nesting material, helps to stimulate ovu- 

 lation in the female. There is some evidence 

 that, in those cases in which the female does 

 most or all of the building, ovulation may 



also depend to some extent on stimuli pro- 

 vided by the nesting material and/or by 

 participation in nest-building. Polikarpova 

 (1940) starting on January 1st kept 11 fe- 

 male house sparrows in cages supplied with 

 a nest box and nesting material, while 10 

 females were kept in cages with neither nest 

 box nor nesting material. On April 28th, 

 when birds caught in the wild had fully de- 

 veloped oviducts and eggs ready to ovulate, 

 10 of the 11 birds with nesting material had 

 enlarged oviducts with a fully formed shell 

 gland, whereas none of the 10 birds without 

 nesting material had advanced beyond the 

 first stage of oviduct enlargement. Vaugien 

 (1948) removed the nest from the cage of 

 female serins while it was being built or 

 just after it was built, and reported that this 

 prevented the birds from laying eggs. When 

 he later replaced nests in the cage, eggs were 

 laid within a few days. Berry (1943, 1944) 

 found that geese of several different species 

 could be induced to lay eggs by the pro- 

 vision of artificial nests, although some of 

 these birds had been in the park for years 

 without laying. Hinde and Warren (1959) 

 found that the absence of nesting material 

 and a nest bowl delay ovulation in domesti- 

 cated canaries. 



The presence of a nest and/or nesting ma- 

 terial clearly facilitates ovulation, at least 

 in some species of birds. Further, the effect 

 of the presence of nesting material is, at 

 least in some cases, quantitatively or quali- 

 tatively different from the effects of stimuli 

 provided by the courtship of the male. 



(d) A special, and most interesting prob- 

 lem is posed by the egg-laying of brood 

 parasites such as the cuckoos and cowbirds. 

 How is the egg-laying behavior of such 

 birds synchronized with the availability of 

 host nests? Although there are some excep- 

 tions (Kabat, Buss and Meyer, 1948; Davis, 

 1958), most birds do not normally lay eggs 

 unless they have first built a nest. Although, 

 as we shall see later, the laying of eggs in- 

 volves hormonal changes which facilitate 

 the subsequent occurrence of incubation be- 

 havior, the brood parasites lay eggs without 

 having built a nest, and without incubating 

 the eggs afterwards. 



Hann (1937, 1941) states that the female 

 cowbird first finds the nest by seeing the 



