CHAPTER V. 



MUTATION, FERTILITY, AND LONGEVITY IN INBRED JAPANESE TURTLE-DOVES.' 

 At the end of the preceding chapter the long and remarkable breeding record 

 of a female Japanese turtle-dove (T. orientalis, 2) was completely presented in 

 the form of tables. That record, together with another closely associated with it, 

 may now be fully discussed. This turtle-dove was kept in captivitj' for more than 

 15 years after her importation from Japan. In the twelfth and fifteenth j'cars of 

 this period she produced no eggs, and in the thirteenth and fourteenth years only 

 4 and 8 eggs respectively. During other years, including mating periods with com- 

 mon pigeons, from 12 to 20 eggs were laid per yea,v. The few eggs of the thirteenth 

 and fourteenth years were fertilized by a son ; one-fourth of these eggs were infertile 

 and 3 of the 9 eggs that hatched gave "mutant" young with whitened plumage. 

 That this bird and her (earlier) mate, both taken wild in Japan, were quite pure 

 T. orientalis is beyond question. They are both shown in pi. 6. Even a slight 

 contamination with any species whatever, except possibly T. turtur of Europe, 

 would have been easily detected in the birds themselves, while a quite uniform 

 and very numerous progeny during many previous years strongly attest the purity 

 of both parents. Finally, the "mutants" themselves are wholly unlike any other 

 species of the genus Turtur, and equally unlike any related genera. These 

 "mutants" are further considered and illustrated in the present chapter. Data 

 tlealing with the successful breeding of one of them is herewith given,- and the 

 fertility and longevity records of inbred, non-inbred, and out-crossed relatives of 

 these "mutants" are also presented. 



THE JAPANESE TURTLE-DOVE MUTANTS OF 1909 AND 19 10. 



It is notable that the three "mutants" under consideration arose from a quite 

 old female when mated with her son, and that two of the three striking variants 

 arose from the very first egg of each year of the two years' duration of the mating. 

 The third arose from the last clutch of eggs which this female ever laid, and this 

 clutch was produced at the extreme end of the season, in September. These 

 "mutants" bear, in order of their production, the numbers 95, 98, and 108. 



The general appearance of these three is shown in a series of illustrations. No. 95 

 is figured in two plates: the live bird, together with plucked, expanded tail 

 feathers (better to show the extent of the "whitening") in pi. 4; alongside a 

 normal T. orientalis (94) of similar age in pi. 4; with its second growth of tail 

 feathers, and expanded at the time of its death in pi. 5. The expanded tail 

 and wing of a normal (94) to compare with the preceding is supplied in pi. G. 

 These illustrations show: (1) the degree of whitening attained in this "mutant"; 

 (2) that a slight advance toward the normal darker color was attained by this 

 bird in the second tail plumage; (3) that the (very) dark centers of the body 



'■ The editor is responsible for the textual statement of this entire chapter and for the tabulated breeding records 

 after 1910. 



^ These data, together with those on fertility and longevity, were supplied almost entirely bv the editor, 1911 

 to 1915. 



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