An island refuge?

In the 1950s, concern about the extinction of the California condor led to a proposal to move California condors to an island in the Pacific Ocean. Here’s a look at that idea.

In a letter to the editor of the Los Angeles Times published on 4 May 1953, Lewis W Walker wrote:

… America’s largest flying bird is on the way out unless they are artificially fed within the preserve or propagated artificially until such time as a breeding stock could be introduced to an island, such as Guadalupe with its goats, or Socorro with its sheep.

In his letter, Walker describes himself as a conservationist and, as evidence, notes his articles in Natural History, National Geographic Magazine, and Audubon Magazine.

Indeed, Walker had been hired by the San Diego Zoo to capture a pair of California condors for breeding in captivity. Just a week after Walker’s letter was published in the Los Angeles Times, Newsweek magazine reported that:

Walker is confident that if he can capture of California condors, they will breed contentedly in the San Diego Zoo’s huge flying cage, where Andean condors have produced several offspring. Then, perhaps, the big birds can be established safely in their own empire on some rocky island.

Alden Miller, a zoology professor at the University of California, pushed back against the relocation idea in the November-December 1953 issue of Audubon Magazine:

As for planting the species on an oceanic island like Guadalupe, the lack of cruising space and the requisite thermal air conditions for soaring there, such as are found on large varied land masses, together with the uncertainties of climatic suitability for breeding and of sustained food supply through the seasons and over a significant period of years, make the hope for success quite forlorn. Even the much more adaptable and ubiquitous turkey vulture has not been successful in colonizing this island.

While that last point seems sufficient to knock down Walker’s idea, I still had 2 questions:

Is there any evidence of California condors living on the Channel Islands off the coast of southern California?

How suitable are Guadalupe and Socorro Islands for California condors?

I’ll take each question in turn.

A July 1960 piece in Sports Illustrated magazine stated:

The Andean condor (Vultur gryphus) sails effortlessly above flatlands and over the ocean to offshore islands. The California condor is not so versatile. It seldom ventures out over the flat-lands four or five miles from its favored Coast Range and has never made it to the Channel Islands, only 30 miles from Santa Barbara.

However, the article “Late Pleistocene History of West Anacapa Island, California” in volume 75 of the Geological Society of America Bulletin reported fossils of an extinct relative of the California condor, Gymnogyps amplus, on one of California’s Channel Islands. In the 1998 book Contributions to the Geology of the Northern Channel Islands, Southern California, Daniel Guthrie reported the finding of California condor bones on another of these islands.

Guadalupe Island and Socorro Island are located off Mexico’s northwestern coast. Guadalupe is about 250 km from the mainland and Socorro is more than twice as far offshore. Guadalupe has a land area of about 250 square km and the area of Socorro is half that.

To put these numbers in context, California’s Channel Islands are 25-125 km from the mainland and, unlike Guadalupe and Socorro, most are visible from the mainland. Santa Cruz, the largest of the Channel Islands, has about the same land area as Guadalupe.

The area of the Sespe condor sanctuary is almost that of Guadalupe and Santa Cruz. This refuge provides for condor nesting but is nowhere near large enough to meet all the species’ habitat requirements.

It is important to add that the Guadalupe caracara, a member of the falcon family, went extinct about a century ago. This species was found only on Guadalupe Island. Also, Socorro is an active volcano, having erupted 3 times in the 20th century.

Based only on this information, my non-expert view is that Guadalupe and Socorro are hardly suitable refuges for California condors. Expert Alden Miller had it right. I cannot help thinking about condors’ predilection for flying great distances. But a condor could fly across oblong Guadalupe’s longest dimension in just half an hour.

Lastly, I note that the relocation idea did not end in the 1950s. At a 1981 conference, a member of the audience asked about the possibility of conserving California condors by relocating them to the Andes Mountains. For more, see the post Santa Clara Valley Audubon Society’s 1981 conference.

The article from Sports Illustrated magazine that is noted above is featured in the post Sports Illustrated.