New evidence on the origin of the fox, ''Urocyon Littoralis clementae,'' and feral goats on San Clemente Island, California

From Islapedia

New evidence on the origin of the fox, Urocyon Littoralis clementae, and feral goats on San Clemente Island, California by Donald Lee Johnson

The island fox (Urocyon littoralis) of the California Channel Islands has long interested evolutionary biologists, mammalogists, and biogeographers. This interest stems in part because the island fox differs in several morphological characteristics from the mainland gray fox (U. cinereoargenteus), most notably in its much smaller stature. The island fox is also of zoogeographic interest because six endemic races occur on a like number of islands that are scattered across some 240 linear kilometers of ocean, from San Miguel Island on the northwest to San Clemente Island on the southeast. The evolutionary history and zoogeographical relations of the island fox have been discussed by Grinnell et. al (1937), DIckey (in Rogers, (1929:445), Stock (1943), Norris (1951:74), Vedder and Norris (1963), von Bloeker (1967), Savage (1967:265), Orr (1968:42), Remington (1971), and Johnson (1972:157-164).

The feral goats of the Channel Islands are of interest because they are voracious modifiers and destroyers of the indigenous vegetation, some elements of which are insular endemics. Goats occur only on Santa Catalina and San Clemente islands, but Farnham (1840) alleged that in the 1840s they also occurred on Santa Barbara and San Nicolas islands.

This note deals with San Clemente Island, and brings new evidence to the long-standing problem of when and how the foxes and goats originated on it. Except for San Clemente Island, there is no reason to doubt that U. littoralis was present on all the larger Channel Islands in prehistoric time. The problematic history of the foxes and goats on San Clemente Island stems from a published conversation that mammalogist J. S. Dixon had in 1920 with a long time resident of the island, Salvador Ramirez, who claimed to have introduced foxes and goats from Santa Catalina Island in 1875 (Grinnell et al., 1937:464). Light was shed on the matter recently when this writer discovered several unpublished 19th century letters, hand-written by Coast Survey Assistant W. E. Greenwell to his superior, A. D. Bache, then superintendent of the Coast Survey. Greenwell was charged with establishing triangulation stations on San CLemente Island during the early 1860s. In one letter Greenwell (1860b) described the general character of San Clemente Island and states:

“Now with the exception of a small island fox no living animal [mammal] is found...”

This letter is dated 2 September 1860, 15 years before Ramirez claimed to have brought his fox pair and goats to the island in 1875. Greenwell's observation suggests strongly that U. littoralis was present on all of the largest Channel Islands, including San Clemente, in prehistoric time (how the fox came to be on San Clemente Island and the other Channel Islands in late Quaternary time is a matter beyond the scope of this paper).

Although the fox dilemma is resolved, a goat dilemma remains. Where were goats introduced to San Clemente? Were they already present in the 1840s as alleged by Farnham (1849:107) and somehow overlooked by Greenwell later? Or did Ramirez first introduce them in 1875? Or, were goats first introduced early in the 19th century, driven to extinction between the 1840s and 1860, then reintroduced by Ramirez?

Although unequivocal answers to these questions go begging, a cautious sifting of the evidence is instructive. First, Farnham's allegation that Santa Barbara, San Nicolas and San Clemente islands were “densely populated with goats” in the mid 19th century is not verified by other accounts (Ellison, 1937; Hardacre, 1880; Greenwell, 1858a, 1858b, 1858c, 1860a, 1860b, 1862a, Phillips, 1927:108). From 1835 to 1853, for example, the only large land mammals known to have inhabited San Nicolas Island were dogs, foxes, and one Indian woman (Ellison, 1937; Hardacre, 1880). In reading Farnham's account it is clear that he never visited or came within eyesight of the three islands about which he spoke. Therefore, his statement must have been based on information provided by others. Farnham wrote in the 1840s when practically nothing was in print on the subject, and word-of-mouth information about what animal live on which island is of low credibility. I might ass that without reference materials even modern investigators are hard pressed to correctly match present feral animals with the islands on which they occur.

Furthermore, it is clear from Greenwell's letters that he and his assistants intermittently camped on, trod, and surveyed the length of San Clemente over a period spanning at least two years, and had goats or other large mammals been present it seems certain that they or their spoor would have been noticed. In fact, Greenwell (1862a) did note:

“...about 150 head of wild sheep...”

subsequent to when he first noted the fox (when the sheep were first introduced is not known). At any rate, Greenwell made no mention of goats for his reports and letters, and it seems unlikely that he or his assistants would have mistaken goats for sheep, although this remains a possibility.

Finally, if it is assumed that, as with the fox, Ramirez did bring goats to San Clemente in 1875 as he intended, he apparently was motivated in part by his belief that neither animal was then present on the island. In this regard the small indigenous fox and its spoor might conceivably have been somehow overlooked for a short time by Ramirez, who was then presumably a newcomer to the island, but he could hardly have missed goats had they been present. Modern visitors to the island are confronted with abundant evidence of goats in the form of droppings, hair, footprints, and even their smell, not to mention the goats themselves. Had feral goats been present in 1875 or before, even in far fewer numbers than now, such signs surely would have apparent to Ramirez and, especially to Greenwell and company.

I conclude that the fox (U. littoralis clementae) was present on San Clemente Island in prehistoric time and, contrary to one published account, was not originally introduced to the island by western man in 1875. However, a pair of U. littoralis catalinae from Catalina Island may have been brought to San Clemente at this time.

Conclusions about the first introductions of goats to San Clemente cannot be considered definite or unequivocal. Yet, because several early reports omitted mention of goats but listed foxes and feral sheep, and because goats presumably were brought to San Clemente Island in 1875, the latter date probably marks the time of their introduction. Sheep were introduced prior to 1862.