What’s a Native Species Worth?

By Dan Moskovitz (he/him)

What is the value of a native species? And is every species of equal value?

Ultimately, the answer to these questions comes down to your values. How many people would truly value a native parasite equally to a kākāpō, kiwi, or takahē? 

Alex Boast probably would. He’s a scientist at the Bioeconomy Science Institute who recently authored a paper showing how the kākāpō’s decline has likely led to the extinction of several of their native parasites. 

Parasites may be unpopular, but there’s the distinctive buzz of an ecologist talking about their special interest in Boast’s voice when asked why he studies them. 

“We think of parasites being kind of icky, and debilitating for species, but they have a role to play in ecosystems,” said Boast. “They shape biodiversity. They prevent one species from becoming overabundant.

“Often, their effect is minimal. But if you remove them, the host becomes a vacant space for potentially more harmful parasites.”

Therefore, the results of parasite extinction could result in worse parasites moving in.

Boast and his team examined coprolite samples—a fancy name for fossilized kākāpō poo—across a timescale stretching from before humans arrived in Aotearoa to the present day. Of those, they found 16 parasite species. Two of those only show up in the modern records. 

Which means either these two species just weren’t found in the historic record, or kākāpō are now dealing with invasive parasites, though Boast is quick to caution that there’s no way to be sure.

13 species of parasite were found only in the ancient coprolites—and were absent from contemporary samples. It seems likely the decline in Kākāpō to around 250 birds could have resulted in the extinctions of their parasites, though Boast is again cautious. Not finding a parasite isn’t necessarily proof it isn’t there. 

“When you have fewer and fewer host individuals, it becomes harder and harder for parasites to cross-transmit because there aren’t enough individuals interacting,” said Boast. 

“If the decline keeps happening, you will inevitably lead to parasite extinction. But, we can’t be sure that’s what happened here.”

One potential cause of extinction is in fact conservation efforts. Boast cites the case of the California condor—an American bird the entire population of which was taken into captivity and treated for pests. Said treatment likely resulted in the extinction of a native louse which parasitized the condors. 

Similarly, the kākāpō population is under the Department of Conservation’s management, who treat the birds for parasites when they are at high levels. Given these parasites could be native, we come back to the question; are all native species of equal value? 

“There's an ethical dilemma now,” says Boast. “Traditional conservation would say we take these individuals and we want to make sure they're healthy. We deworm them, and get rid of all the parasites.”  

“But there’s a lot more to consider. Deparasitizing these birds could leave them vacant for worse parasites. And then there’s ethical questions of what conservation should be about? 

“Is it just about conserving cute, cuddly things? Is it really ethically right to potentially be making parasites extinct based on some kind of prejudice we might have against them?”