SANTA CRUZ RUFOUS-CROWNED SPARROW 941 



In addition to the disappearance of rufous-crowned sparrows some- 

 time after 1863 from Santa Catalina Island, where song sparrows 

 (Melospiza melodia) are also unexpectedly absent as breeding birds, 

 there seems to be considerable question as to the presence of rufous- 

 crowned sparrows on Santa Rosa Island, separated from the still 

 larger Santa Cruz Island by only about 6 miles. A. H. MiUer (1951b) 

 gives a thorough comparison of the avifaunas of these two neighboring 

 islands, both of which "have grassland, chaparral (both tall and 

 open, and low and wind-cropped), oak woodland, and an artemisia- 

 opuntia(cactus)-grass association. * * * [The last] is perhaps 

 roughly of equal amount on the two." These and the neighboring 

 islands to the east and west, Anacapa and San Miguel, A. H. Miller 

 points out, "almost certainly * * * have been connected with the 

 mamland at periods in the Pleistocene time." Aliller's own visit to 

 Santa Cruz and Santa Rosa extended from Mar. 5 to 13, 1950, and 

 included extensive collecting of specimens in various parts of each 

 island. Of the rufous-crowned sparrow he \mtes: 



With respect to resident sparrows, it was at once evident that the artemisia- 

 opuntia-grass association on Santa Cruz was well and exclusively populated by 

 the Rufous-crown (Aimophila ruficeps) whereas across the channel in identical 

 vegetation and on the same type of sloping terrain on Santa Rosa nothing but 

 Song Sparrows {Melospiza melodia) occurred. This habitat is a normal one, in 

 terms of mainland conditions, for Rufous-crowned Sparrows. But, the island 

 population of the endemic race A. r, obscura is, I think, somewhat more dense in 

 it than is the population of the southern Californian coast. On Santa Rosa the 

 Song Sparrows of the race M. m. clementae occupy this cover without limitation 

 to stream courses or canyon bottoms in a way not done by the mainland race of 

 southern California even on slopes facing the ocean. Song Sparrows have spread 

 out ecologically, so to speak, to occupy the habitat of Aimophila and at times 

 situations remindful of that of the resident White-crowned Sparrows {Zonotrichia 

 leucophrys nuttalli) of the coast of San Luis Obispo County. It is rather clear 

 that with lack of competition from somewhat similar kinds of sparrows and with 

 a range of adaptability, quite possibly enhanced by inherent adaptive changes, 

 Melospiza has come to dominate an unusual range of vegetative conditions on 

 Santa Rosa. The foggy climate of the island doubtless is an aiding factor, en- 

 abling the moisture-seeking Song Sparrows to occupy brushlands near the sea 

 as do other races much farther north in an even more humid belt. Yet it should 

 not be forgotten that on the adjoining point of Santa Cruz Island in equally fog- 

 swept cover Song Sparrows are absent. 



After reviewing the few records of song span-ows on Santa Cruz 

 Island, A. H. Miller concludes that they "make it clear that the 

 Song Sparrow is not a dominant species on the island and indeed is 

 apparently lacking in the artemisia-opuntia-grass and chaparral 

 habitats." He then continues: 



Concerning the presence of Aimophila ruficeps on Santa Rosa Island, we have 

 only the report by Pemberton (Condor, 30, 1928:148) that O. W. Howard noted a 

 pair on April 2, 1927. No record specimen was taken and there is a chance of 



