Jan., 1901 1 THE CONDOR I3

Dichromatismin the Genus Carpodacus

RICH;ZRD C. MCGREGOR.

[Read before the Northern Division of the Cooper Om. Club,1 CCASIONAL, finches, in which birds varying from the normal. Of sev- yellow is present or even pre- enteen males before me, nine, or over 0 dominant over the red, must one-half, are more or less yellow. In come to the notice .of every field or- two of these the rump, head, and breast nithologist of the west; in fact we may are clear lemon yellow, in a third the lcok for some yellow feathers in about feathers are about equally red and yel- one-half the males of this group. Loxia, low, of a pale washed-out look. The PimkoLa and probably other genera remaining six have a few yellow feath- have a yellow phase of regular occur- ers irregularly mixed with the crimson. rence in the immature plumage. It is The proportion of yellow birds which this dichromatism which led me to make really occurs in probably less than the a few remarks before the Club-not above figures would indicate as this with the intention of reporting anything series was selected, somewhat, with a new but with the hope that some mem- view to getting the abnormal examples. bers might take an interest in what has Among mainland birds (C. nz. O~WW- interested me. us), great deviation from the crimson The following notes were made on type is rarer, though even here it is specimens of Carjodaci in my collection surprising how many shades of color and treat of the occurrence of yellow occur. In a series of over fifty males among the North American species. I before me including skins from Col- am unfortunate in having no repre- orado, nearly the whole length of Cali- sentatives of Mexican forms but these fornia, and four from northern Lower would doubtless show the same varia- California there are thirty-three in tions in plumage color. which more or less yellow occurs. How- liellow‘ feathers are rare in Carpoda- ever, four only are strikingly different cm $uq?w~~us caLifoorniczts’ and I have from the normal, three being yellow never seen them in C. cassini. Of the with no red and one almost orange with former race Mr. T. E. Slevin has two very few yellow feathers. Twenty- males in which a few yellow feathers nine possess from one or two to a dozen occur on the breast. They were taken lemon colored feathers mixed among the at Fairfax, CaliTornia, in December. In red. Among the red examples, too, the subgenus Rwrica, including as it there is great variation. Many are a does the so-called house finches, the deep rose pink (young of the year?), yellow phase is common and these others are crimson or near vermilion. plumages will now be described for Birds taken just before or during breed- each race examined. ing season have an indescribable lustre Among the finches from the San Ben- which is only ascribable to intensifica- ito Islands CC. mq~egori). I have never tion or addition of pigment. seen two alike. The colors range from Of six examples from Coronado and bright crimson through orange into San Clemente Islands (C. clemenfis). one lemon yellow with all manner of varia- from each island has a few yellow tions resulting from combinations of feathers; another from Coronado is al- these colors and their shades or tints. most brick red. It is impossible to take any example Even in C. r:~6evrimus frcm San Jose and s3y it is the typical ccloration. de1 Cabo, we find cases of reversion, for The finch of Guadalupe Island (C. although this form is very‘ red ’ as its axplus) shows more stability in its col- name indicates, there are cccasional a ration but even here we often find specimens with yellow feathers. I have I4 THB CONDOR 1 Vol. III managed to get six of these. Two are finches in my collection. He says3 in immature plumage, one shows an in- “It is difficult to say whether the clination to orange, and three have yel- change in color of the caged house low in patches. finch (Carpodacus mexicanus frontalis) Pains have been taken to make this from red to yellow is due principally to list in some detail in order to show how a change in food, or to the confinement frequent is the tendency to yellow; so and general deterioration of the system frequent is it that we are hardly justi- from captivity. Food nevertheless, fied in calling it an abnormal condition. plays some part in this, as well as in The hypothesis that yellow is a more many changes in the color of birds in primitive color than red finds additional the wild state, which, with the present evidence in another genus, Cyanospiza. lack of experimental data, are far too A spring male of C, ciris taken in complex even to be surmised.“6 Georgia has one yellow feather in its I have quoted at length from Keeler breast and five in its throat. Another in order to emphasize the richness of male of this species shows yellow on material ready to our hand. Here is an the flank.= excellent chance for interesting and That these facts point to an ancestral valuable experimentation. A study of bird of yellow plumage seems most the color change in our commonest bird reasonable to answer a question as to would give big returns for the time in- why so many birds are off color. vested. For such work, however, one Mr. Charles A. Keeler has suggested should be permanently located where that yellow is the more primitive color continuous out-of-door work might be and red an intensification of the same done for a year or more. pigment, although he gives no experi- One more extract from Keelers’ work mental data to support his opinion. So may not be out of place. “The most high an authority as Dr. R. W. Shu- significant interrelation of colors, how- feldt wrote me, October IO, 1899, in re- ever, and one which I believe to be of gard to this subject: “I am inclined to wide application in the explanation of agree with Mr. Keeler that yelloze! birds bird colors, is that bet\ceen yellow and preceded red ones in the history of the red. Whether these two colors are pro- group in time, and thus viewed, red may duced by the same or a different pig- be but an intensification of the former ment I am unable to say; but, however color.” Mr. J. Armory Jefferies says: this may be, there is a high degree of “Red feathers as those of the Flamingo, probability that the red is simply an in- Cardinal Bird, and the like, are so col- tensification of the yellow. There is ored by a red pigment similar to the much to show that yellow is a more yellow one.“* primitive stage than red, and that the Keelers has called attention also to latter has always or nearly always been the fact that the House Finch when deve!oped from the former.“7 kept in captivity changes from red to It is to be hoped that someone who yellow, and that 4”many birds appear to has time and facilities will feel enough become more brilliant in color as the interest in this matter to make at least breeding season approaches without a study of the moult and of the effect of either a moult or the wearing away of food supply, varied as to quantity and the tips of the feathers.” This last and quality. point is indicated by the series of

I. NoTrz-Since writing the above I have examined a 2. Bull. Nut. Omith. Club. VII. P. 131. beautiful series of Hawaiian Island species, &e.stiavia‘ core - 3. Evolution of Colors of N. A. Land Bds. P 156. inea, iu the collection of Mr. H. W. Henshaw of Hilo. In 4. 1. c. p. 136. the adult plumage this bird is entirely red. The young. 5. 1. c. p. 229. however, are yellow and Mr. Henshaws’ lot shows the 6. See otl this subject, Birtwell, Auk XVI. p. 313. gradual change from yellow to red. 7. I. c. p. 154.