Ancient bird droppings reveal massive parasite extinction

In the story of conservation, certain characters steal the spotlight. We celebrate the survival of endangered animals, restore their habitats, and marvel at their recovery.

But hidden beneath these victories is a quieter, almost invisible loss – one that rarely earns public attention or sympathy. This is the story of the kākāpō and the silent extinction of the parasites that once lived alongside it.

Vanishing kākāpō parasites

Researchers from the University of Adelaide, Manaaki Whenua-Landcare Research, and the University of Auckland have uncovered a surprising shift in the lives of New Zealand’s kākāpō parrots. Over 80 percent of the parasites found in their droppings before the 1990s have disappeared.

Using ancient DNA and microscopic analysis, the team studied feces dating back more than 1,500 years.

The researchers discovered that nine of the 16 parasite types vanished before the 1990s, the same period when the birds began full-population management. Another four species disappeared after this conservation work began.

Parasites disappear with their hosts

“Despite their sometimes negative portrayal, parasites are increasingly appreciated for their ecological importance,” said the University of Adelaide‘s Dr. Jamie Wood. These organisms are among the most successful and widespread lifeforms on Earth.

Parasites are not always harmful invaders. Many play subtle yet vital roles in ecosystems. They help train host immune systems, regulate disease, and sometimes outcompete more dangerous parasites.

Almost every free-living animal harbors parasites, making them one of the most widespread life forms. Yet this close connection creates a risk.

Parasites depend heavily on specific host species to survive and reproduce. If the host population declines – due to disease, habitat loss, or conservation interference – the parasites may also disappear.

These losses often go unnoticed, yet they could have lasting effects on host health and ecological balance. When parasites vanish, we may lose not just pests, but essential contributors to the natural world.

Parasites may vanish before their hosts

This study focuses on the concept of co-extinction, a process where one species disappears because it depends entirely on another species that is going extinct.

In this case, the dependent species is a parasite, and the host is the species it lives on. If the host population declines or dies out, the parasite often can’t survive. But the key point here is that parasites may vanish even before the host does.

“Predictive models indicate that parasites may go extinct before their hosts during the coextinction process as opportunities to transmit between host individuals diminish,” said Dr. Wood.

Even if the host species is saved later through conservation efforts, its lost parasites might never come back. This has unknown consequences.

Parasites are hard to study, because they’re rarely recorded before they disappear. By the time scientists realize they’re gone, it’s too late to learn about what role they played.

Wider implications for biodiversity

The study highlights that parasite extinctions might happen more often than previously thought.

“Our new research indicates that parasite extinctions may be far more prevalent than previous estimates suggest, with unknown impacts on their hosts and their ecosystems,” noted Dr. Wood.

Study lead author Alexander Boast from Manaaki Whenua–Landcare Research was taken aback by the findings.

“The level of parasite loss in kākāpō was greater than we had expected, and very few parasite species were found in both ancient and modern kākāpō populations,” said Boast.

“Thus, it seems that endangered species everywhere may possess fractions of their original parasite communities.”

Protecting kākāpō parasites from extinction

As biodiversity declines, the loss of less visible species like parasites may also increase.

“Global rates of climate change, ecosystem modification, and biodiversity decline continue to rise, which means there is an increasingly urgent need to recognize and understand the downstream impacts on dependent species, such as parasites, mutualists, or predators,” said Dr. Wood.

“Documenting parasite extinction, how quickly it can unfold, and estimating the number of presently threatened parasites are key first steps toward a ‘global parasite conservation plan’ and supporting informed predictions for past, present, and future parasite losses.”

The study is published in the journal Current Biology.

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