102 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



COLOR IN OWL X ROCK CROSSES. 



Three .separate matings of African owls {Coliimba turhata dom. var.) with 

 domestic rock-pigeons''' {C. livia dom.) seem to show that color is here sex-limited 

 in its inheritance. The editor finds no comment on the data, which are presented 

 in full (tables 82 to 83a). The reader will readily see, however, that young of two 

 colors are produced and that all of the known females were of the light "owl" 

 color, and that all known males were of dark color. 



Two pairs of owl x rock hybrids were inbred. From pair 1, 3 red offsjiring 

 were obtained in late season and "out of sea-son" (table 84). This case further 

 illustrates the point, elsewhere mentioned by the author, that a commingling of 

 colors quite often produces red, though neither parent nor grandparent exhibited 

 this color. The second pair was composed of the male of the preceding pair 

 mated to his half-sister. Though this female showed traces of "brown" in the 

 chequered parts of her wing, neither of the resulting G offspring was red. In this 

 case also, however, the last clutch of the season produced two birds of the lightest 

 color present in the series. It may be pointed out that there are three obvious 

 reasons why one should expect fewer red offspring from pair 2 than from pair 1 : 

 (1) the degree of inbreeding is less; (2) the eggs were produced from a better 

 part of the season; and (3) the mother of the female of pair 2 was darker than the 

 mother of the dam used in pair 1. Females of dark and of light color appear in 

 the Fj generation. 



FERTILITY AND SEASON IN CROSSES OF COMMON PIGEONS WITH FERAL COLUMB/E. 



A few data are available on the crosses of the stock-dove {Columba oenas) and 

 the wood-pigeon (Columba palumbus) with domestic pigeons. In the single record 

 for the stock x domestic cross a complete failure of fertility is found in the late 

 autumn (table 85). The young produced from the stronger germs of the season 

 nearly all died early, but this was the result of their feeding and is probably not 

 otherwise significant. One of the male hybrids was fully fertile with C. livia dom., 

 and the author notes, of the last young of the season (table 86), that "color here 

 seems to be that of the earlier hatched young." 



A cross of C. admista dom. x C. -palumbus proved remarkably infertile (table 87) ; but 

 since only a single female was tested , this cross may be more fertile than is here indicated. 



Two common pigeons obtained in the autumn of 1910 from a fancier yielded, 

 during the autumn, but two clutches of eggs. Developmental power was then at a 

 very low point, as is shown by the complete failure of the last clutch (October 7 

 and 9) to develop, and by the production from both eggs of the earlier clutch (Sep- 

 tember 17 and 19) of "two young with much white. "'^ The male was a brunette — 

 quite black. The dam was red with white primaries and with the so-called "guinea- 

 mark," i.e. a small triangular white tip to many of the feathers (G 9). The dates 

 of the death of the parents, the male Ijefore February 15, 1911, and the female on 

 August 18, 1911, is a further evidence of weakness in these birds at the time they 

 gave rise to the "whitened" young. 



" It will at some time be of interest to note the order of the sexes from eggs of C. livia dom. Within the individual 

 clutches of these birds the order of sexes from the eggs varies greatly from the order known for most pure wild species ; 

 the first egg here often gives rise to a female, the second often to a male; and studies by the editor have further shown 

 that the size relations of the yolks of the two eggs of the C. livia dom. clutch are similarly variable. 



'* These birds were photographed October 14, 1910, but copies or plates are not .available to the editor. 



