CHAPTER X. 



ZENAIDURA AND ITS CROSSES WITH ZENAIDA AND HYBRIDS. 



The results of crossing mourning-doves {Zenaidura carolinensis) with a species of 

 the related genus Zenaida are here presented in a series of tabulated breeding 

 ic'cords. The data for fertility, sex, and longevity, though not complete, are as nearly 

 so as it has been possible to make them. The records for the breeding of pure 

 mourning-doves and pure zenaidas are also given. Of chief interest, however, is the 

 appearance of a "mutant" from Zenaida vinaceo-ruja and the behavior in inheritance 

 of the new character in crosses with Zenaidura and its hybrids. The full consider- 

 ation of this "mutation," together with a large group of illustrations, is given in 

 Chapter IX of Volume I, where the nature and phylogenetic relations of the "new" 

 character are treated (by the author) in connection with the broader subject of the 

 direction of evolution of the color-pattern of pigeons in general. Much of the 

 l^resent textual statement and a tabulated summary have been supplied by the 

 editor; the author's statements are here given the form of quotations. 



The records for 6 pairs of mourning-doves^ (tables 89 and 90) show that these 

 l)irds breed in captivity with nearly full fertility. In reciprocal crosses with the 

 closely related genus Zenaida they are about equally fertile (tables 91 and 93). 

 This is a result parallel to that already found (Chapter VII) in crosses of two other 

 genera which are not distantly related to each other, Turtur and Streptopelia. Even 

 inter se matings of these hybrids (tables 94, 95, 97, 98) are almost fully fertile; 

 when back-crossed to the parent species they are, with Zenaida at least (table 96), 

 quite fertile. This maintenance of high fertility by the mourning-doves in their 

 crosses with Zenaida is, however, in marked contrast with the very low fertility of 

 mourning-doves when crossed with the much more distantly related forms {Strep- 

 topelia) to be described in Chapter XL 



The inbreeding of 3 pairs of hybrids supplies a group of offsi)ring of shorter 

 life-term than is elsewhere fovmd in these records. Th(^ data are fully given in 

 table 97. 



A short consideration only will be given here to the "mutation" which arose 

 in the breeding of Zenaida vinaceo-ruja Ridgway. A statement concerning its 

 character and origin, and another touching upon its behavior and permanence in a 

 long line of the breeding tests, must suffice.- The various tabulations present most 

 of the data specially germane to the present volume. 



In this "mutation" we have to do with (1) a "mutational" color-character — a 

 white triangular mark at the tip of all of the feathers of several parts of the body; 

 (2) the "mutational" character exists only in the juvenal plumage, the adult plu- 

 mage of mutant and normal being alike; (3) the new character is clearly a strong 

 modification of a region of the feather which is already differentiated slightly in 

 the direction of the much-strengthened "new" character; (4) the mutational 

 character exists as a specific character in Columba guinea, in some other pigeons, 



' See plate 19. 



2 As noted above, most features of this mutation are fully treated in Chapter IX, in Volume I. Only the breeding 

 data may appropriately be consitlcred here. — Editor. 

 114 



