CHAPTER XI. 



BLOND AND WHITE RING DOVES CROSSED WITH MOURNING-DOVES, 

 COMMON PIGEONS, AND THE EUROPEAN TURTLE-DOVE. 



The three groups of crosses presented here afford an additional o})portunity to 

 observe the following facts or situations: (1) the reduced fertility which follows 

 from the mating of forms more and more separated phylogenetically; (2) the 

 appearance of males exclusively in the progeny resulting from the most distantly 

 related crosses; (3) the effects of season and hybridism on fertility and sex, and in 

 isolated instances of the effect of season on the dominance of color.' 



The same forms — ^blond and white ring-doves — were mated to mourning-doves, 

 which are classed in a different subfamily, with common pigeons, which belong to a 

 different family, and with the European turtle-dove, which belongs to a related 

 genus. The generic and subfamily crosses were more fertile than those of family 

 difference, and from the crosses of genera both male and female young were obtained 

 The crosses involving birds of different families gave only male offspring, except in 

 two isolated instances in which hybrid rnales were used with a female (homer?, 

 stray bird) of uncertain (hybrid?) origin. From these pairs 3 birds were obtained 

 which were classed as females, but this classification was probably based solely 

 upon their behavior in copulation ; no sex data, obtained at the time of death, can be 

 found for either of these three offspring. The subfamily crosses gave also only male 

 offspring. The generic cross described here is apparently perhaps less fertile than the 

 subfamily cross, due chiefly to the high degree of hybridism involved in the birds 

 used as parents, and to more extensive inbreeding in this series of generic crosses. 



Complex hybrids were formed in the various groups, and these afforded oppor- 

 tunity for a study of the possibility of the "splitting" of the very distinct characters 

 of the very distinct parental forms. This particular aspect of the results is, however, 

 separately considered in Chapter XVII. In the crosses of the ring-doves with the 

 turtle-dove there is found a limitation of the inheritance of color by sex. In the 

 first group of crosses a number of birds were used as parents whose exact origin 

 may be obtained from the breeding data which is tabulated in connection with the 

 preceding chapter. 



BLOND AND WHITE RINGS CROSSED WITH THE MOURNING-DOVE AND ITS HYBRIDS. 



In crosses of the mourning-dove, and of several grades of its hybrids, with the 

 closely related genus Zenaida, all were found (in the preceding chapter) to be almost 

 or quite completely fertile. 12 matings of these forms with other doves which are 

 commonly classed in a different subfamily are here recorded, and a low or an 

 extremely low fertility is found in every case; 5 of these pairs (tables 100 to 102) 

 involve the primary cross — Zenaidura carolinensis x St. risoria; 4 pairs (tables 

 103 and 104) are pure carolinensis x risoria-alba hybrids (F. of reciprocal crosses) ; 

 2 pairs (tables 105 and 106) are F, male Zenaida x Zenaidura hybrids mated with 

 female pure St. risoria in one case and with pure St. alba in the other. A twelfth 



' It has been found necessary for the editor to write this and other introductory matter for most of the sub- 

 divisions of the present chapter. 



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