Extinction is a double act

Losing any species is tragic and shameful, but too often we’re not watching closely enough to see the full story.

Illustration by Kallum Best

Illustration by Kallum Best

This is an editorial for Issue 31 of Lateral by Life Science editor Andrew Katsis. Although he studies birds for his PhD research, he will in future show a greater regard for their parasitic sidekicks.

On April 19, 1987, the world’s last wild California condor, a male named AC-9, was captured with a cannon net while roaming the Bitter Creek National Wildlife Refuge in southern California. By happy accident, it was Easter Sunday — perhaps resurrection was in the air, after all, for this critically endangered bird. AC-9 was taken to the San Diego Wild Animal Park, soon to join the other 26 members of his species in captivity at two Californian zoos. According to a press release by the US Fish and Wildlife Service, veterinarians pronounced AC-9 “healthy and in good condition,” and he joined his comrades after a brief quarantine.

What the press release failed to mention was that another species had just quietly gone extinct. As each condor entered captivity, it was dusted with pesticide as a routine quarantine measure. Among the parasites that tumbled to the ground, dead, were perhaps the last members of Colpocephalum californici, a species of chewing louse that exclusively parasitised California condors. As one species was being pulled back from the brink, another was eradicated from the earth.

No doubt few will mourn the California condor louse, but nor should we dismiss its importance. We know extraordinarily little about the condor louse and how it interacted with its only host. When the species was first described, in a 1963 article, the authors wrote: “Since the California condor now is very rare, these 9 lice may well represent all that will ever be found.” Was C. californici just a blood-sucking free-rider, or was their relationship more complex? We will never know. These two species had evolved together for thousands of years, but from here on the condor must go it alone.

Extinction is rarely an isolated incident. One loss kicks off a cascade of tumbling dominoes, rippling across the ecosystem. The long, sad history of bird extinction has an afterglow in the parasite realm: the South Island bush wren, Norfolk Island pigeon and Cuban Red macaw, all now extinct, each took their specialised parasites with them to the grave. New Zealand’s little-spotted kiwi still persists, owing to a successful conservation programme, but its parasite, Rallicola pilgrimi, was probably lost in the process.

Invertebrates such as these are dramatically underrepresented on threatened species lists — not because they are necessarily more secure than vertebrates, but simply because there are so many species, each receiving only a sliver of research attention. Vesk’s plant-louse (Acizzia veski), for instance, is confined to a single wattle species within a square kilometre of Stirling Range National Park, Western Australia, and has been assessed as critically endangered. But this listing is very much the exception, with a long list of threatened lice species — some living in the same restricted area — forgotten on the sidelines.

Whether these parasites are worth saving, given our limited conservation dollars, is an open question, but it’s a question we should at least be asking. Writing to the journal Nature in 1993, entomologists Nigel Stork and Christopher Lyal lamented our general disregard for endangered parasites and urged greater awareness among conservationists. “There may be conflicts in conservation needs,” they wrote, “forcing us to bid farewell to the gorilla louse or the lice of the Californian condor while retaining their hosts. If so, we should do so in the full knowledge of what is being lost.”



Too often, scientists are so dazzled by the headlining act that we forget to notice the quiet, influential forces in the background. And so, in this issue, we momentarily nudge Batman to one side to talk all about Robin. Whether our sidekicks take the guise of an ancient language, a psychological symptom, or a Russian musical companion, we would do well to keep them by our sides.