As conservationists race to protect endangered species like New Zealand’s beloved kākāpō, a new study reveals a startling consequence: the silent extinction of their parasites.
Researchers analyzing 800 years of kākāpō droppings found that more than 80 percent of parasite species detected before the 1990s are now gone. The findings, published in Current Biology, suggest that even as kākāpō populations recover under intensive management, the microscopic life they once carried may be vanishing forever — with unknown consequences for ecosystems.
Centuries of Loss, Hidden in Feces
The kākāpō, a critically endangered flightless parrot, once roamed New Zealand in abundance. Today, only about 250 individuals remain, each carefully tracked and monitored by conservation teams. To understand how the bird’s parasite communities have changed over time, an international team of scientists from the University of Adelaide, Manaaki Whenua–Landcare Research, and the University of Auckland analyzed over 200 ancient and modern kākāpō scats, some more than 1,500 years old.
They found that of 16 distinct parasite taxa identified in pre-1990 samples, only three remain in today’s population. Nine disappeared before the kākāpō came under full conservation management in the 1990s, and four more have vanished since.
Why Parasites Matter
It may sound like good news to lose a few parasites, but researchers urge caution. “Despite their sometimes negative portrayal, parasites are increasingly appreciated for their ecological importance,” said Dr Jamie Wood of the University of Adelaide, a coauthor of the study.
“Parasites are among the planet’s most ubiquitous, successful, and species-rich groups of organisms, and nearly all free-living species harbor some parasites,” he explained. “They may help with immune system development and compete to exclude foreign parasites that may be more harmful to their hosts.”
When a parasite goes extinct alongside its host, it’s known as coextinction. And as Dr. Wood noted, these losses often happen faster than host declines. “Predictive models indicate that parasites may go extinct before their hosts during the coextinction process as opportunities to transmit between host individuals diminish.”
Key Findings
- Over 800 years of parasite data were collected from kākāpō droppings
- 13 of 16 parasite taxa seen before 1990 are absent in current populations
- Four parasite species likely went extinct even after conservation efforts began
- Host-specific parasites appear especially vulnerable
- Parasite loss may reflect habitat changes, low transmission rates, and veterinary interventions
Ripple Effects Through Ecosystems
The researchers believe these findings highlight a broader, overlooked threat within conservation biology. “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,” said Dr. Wood.
Lead author Alexander Boast from Manaaki Whenua–Landcare Research was struck by the scale of loss: “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. Thus, it seems that endangered species everywhere may possess fractions of their original parasite communities.”
Time for Parasite Conservation?
Although parasites are rarely part of conservation planning, the study calls for a shift in thinking. “Global rates of climate change, ecosystem modification, and biodiversity decline continue to rise, which means there is an increasingly urgent need to recognise 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.”
Journal Reference
Journal: Current Biology
Title: Long-term parasite decline associated with near extinction and conservation of the critically endangered kākāpō parrot
Authors: Alexander P. Boast, Jamie R. Wood, Nicola Bolstridge, George L.W. Perry, Janet M. Wilmshurst
DOI: 10.1016/j.cub.2025.07.029
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