Sowing Wild Oats
Goat Life on San Clemente Island
There's an island 68 miles west of San Diego, controlled by the U.S. Navy. San Clemente Island is approximately 21 miles long. The north tip is 1½2 miles wide, and the island flares to a width of about 4 miles. The total area is around 57 square miles. It shares the temperatures of San Diego, but the precipitation is much lower. San Diego may average 12 or 16 inches of rain per year, but San Clemente Island averages 5½ inches. And it's windy, too.
In 1973, there were at least 15,000 goats there. Even the Navy, which is respected for their accuracy, found it a bit tricky to count feral goats on the hoof. There may have been 18,000. What did the goats do? Eat. Breed. And other 'goaty' things. The island is covered in wild oats. Being goats, they would naturally have been foraging the native and other non-native plants as well.
San Clemente Island is made of volcanic rock. Sure, there's dirt and vegetation on it, but the strata is not the same as is found on the mainland in nearby San Diego. Because it is not a very old island, geologically speaking, the canyons of the island are V-shaped, not U-shaped. But the goats never minded the precipitous sides of the canyonsit was in the canyons that they had their midmorning siestas or cud-chewing breaks. They would sleep on the sides of the canyon rim. The goats that left San Clemente Island had great hooves from all that rock-climbing.
Volcanic rock has its downfalls, though. There are no freshwater streams on San Clemente Island, and no subterranian streams. To get water, the goats relied on watershed seeps and pools that would form in the canyon bottoms. In the summertime, the water would dry up, and the goats then settled down in the shade and waited it out. One canyon had more water than mosta large herd of about 200 goats occupied a knoll in it. The knoll was covered in several inches of "nannyberries." Pretty popular spot!
The San Clemente Island goats would have a few breeding seasons per year, and herds would be mixed and very active. When it wasn't breeding season, the bucks would get together into bachelor herds while the does did the same. Does usually had twins, but often had single or triplet births. The goat population on the island affected the birthrate, so as there became fewer goats, the birthrate increased. When the population was sparse, 10% of births were triplets.
Goats on San Clemente Island came in many colors. The standard black-and-brown "buckskin" pattern by far the most common. But there were also all-brown goats, goats that appeared black, goats with white patches, and goats that were all-white, or at least rosy-white or creamy-white. They were not significantly smaller than the goats we have on the mainland today. It was not uncommon for an older adult doe to be just over 23 inches tall.
The goats were healthy on the island. Their coats and hooves were in excellent condition. The goats were subdivided into many herds of varying size, and lived and bred in what appeared to be a contented state.
For a peek at a summary of goat health on San Clemente Island, you may wish to view a one-page tabulation summary by Dr. Phyllis H. Larsen. Needless to say, her paper goes into greater and fascinating detail, but is not published in entirety on this site.
How's the selenium on San Clemente Island? Just how much kelp were they eating on the shoreline? We're still investigating. . .
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Many thanks to J., Phyllis H. Larsen, and to Dawn Seward for their contributions to the information on this page.