2nd California Islands Multidisciplinary Symposiumhttp://hdl.handle.net/10139/9502024-03-29T07:06:16Z2024-03-29T07:06:16ZBreeding Land Birds of the Channel IslandsDiamond, Jared M.Jones, H. Leehttp://hdl.handle.net/10139/41272013-08-08T23:01:50Z1980-01-01T00:00:00ZBreeding Land Birds of the Channel Islands
Diamond, Jared M.; Jones, H. Lee
Biologists are familiar with the thought that islands have unique scientific value as natural laboratories where the mainland species pool is reshuffled by differential immigration, extinction, and evolution to form new communities of fewer species. As material for studying these natural experiments, birds of the Channel Islands are of special interest. The reason for this interest is not that the birds themselves are unique: Channel Islands birds are far less distinct than those of the Galapagos (e.g., see Power 1980), and they are also less distinct than the Channel Islands plants that Philbrick (1980) has discussed. But birds are the most easily observed, best-studied organisms on the Channel Islands, and hence they are the organisms for which we have the most detailed information on ecological topics such as population dynamics, niche shifts, and competition.
1980-01-01T00:00:00ZThe Present Status of the Garter Snake on Santa Catalina Island, CaliforniaBrown, Timothy W.http://hdl.handle.net/10139/41262013-08-08T23:01:49Z1980-01-01T00:00:00ZThe Present Status of the Garter Snake on Santa Catalina Island, California
Brown, Timothy W.
For 33 years, only two specimens of the garter snake (Thamnophis couchi hammondi) were recorded for Santa Catalina Island and the status of this species remained unknown. In August 1974, a small population was discovered in the stream and reservoir in Cottonwood Canyon. The species apparently occurs nowhere else on the island.
Unlike most two-striped mainland specimens, garter snakes on Santa Catalina lack any pattern, being a uniform olive-brown with pale buff lips and chins. In this respect they most closely resemble a different species from central Baja California and a conspecific population near Lompoc on the California mainland.
The ecology of Cottonwood and other stream canyons on Santa Catalina is discussed, as are human impacts on garter snakes, and recommendations for conservation measures.
Finally, rafting is proposed as a mechanism by which garter snakes from the Lompoc region might have founded the population on Santa Catalina Island.
1980-01-01T00:00:00ZDistribution of Bats of the California Channel IslandsBrown, Patricia E.http://hdl.handle.net/10139/41252013-08-08T23:01:49Z1980-01-01T00:00:00ZDistribution of Bats of the California Channel Islands
Brown, Patricia E.
The power of flight has preadapted bats for island colonization. This accounts for their disproportionately high representation in the terrestrial mammalian fauna of the California Islands. Of the eighteen species of native mammals found on the islands (excluding man and marine mammals), eleven, or 61 per cent, are bats. Some bat species are better dispersers than others, but not only must a bat be capable of crossing the water barrier, it must find suitable food and habitat upon its arrival. Bats have voracious appetites and may consume up to 25 percent of their body weight in insects daily. Some are specific in their food requirements, while others are generalists and opportunists, snatching up any insect within a certain size class. Needless to say, generalists are better island colonizers since the specialist may not find its favorite food item present on the island. Bats with specific roost preferences, such as trees or rock crevices, may find a barren sandy island a difficult place on which to live and reproduce. In this paper, I will attempt to summarize what is known about the distribution of bats on the islands and provide new data resulting from my own field work.
1980-01-01T00:00:00ZDivergence in the Island Night Lizard Xantusia riversiana (Sauria: Xantusiidae)Bezy, R. L.Gorman, G. C.Adest, G. A.Kim, Y. J.http://hdl.handle.net/10139/41242013-08-08T23:01:46Z1980-01-01T00:00:00ZDivergence in the Island Night Lizard Xantusia riversiana (Sauria: Xantusiidae)
Bezy, R. L.; Gorman, G. C.; Adest, G. A.; Kim, Y. J.
The island night lizard, Xantusia riversiana Cope (Fig. 1), is found only on Santa Barbara, San Clemente, and San Nicolas Islands off southern California (Fig. 2). The species is sufficiently divergent in morphology from its mainland relatives, X. vigilis Baird and X. henshawi Stejneger (Fig. 1), that it has been placed in the monotypic genus Klauberina by Savage (1957, 1963). Regardless of whether it is accorded generic (Savage 1957) or subgeneric (Bezy 1972) rank, X. riversiana is clearly more divergent than the other living vertebrates of the California Channel Islands, suggesting that it may have been present longer than other species on one or more of the islands. Moreover, casual observations indicate that there may be greater morphological differences between the island populations of X. riversiana than were documented by earlier work (Savage 1951, Smith 1946). In an effort to further clarify the evolutionary history of the species, we have compared electrophoretically determined genetic-distances and divergence time estimates between the island populations with those between the species of Xantusia, and have reappraised inter-island differences in karyotypes, scalation, coloration, body size, clutch size, and variability.
1980-01-01T00:00:00Z