The Possible Ecological Consequences of Moa Extinction in New Zealand

Map of New Zealand, showing that its territory is mainly composed of the North and South Islands（Image source：NordNordWest， CC BY 4.0 ）

New Zealand is an island nation composed mainly of two large landmasses, the South Island and the North Island. Because these islands have remained isolated from other continental landmasses for approximately 52 million years, the country developed an exceptionally distinctive ecosystem.

One of the most striking characteristics of this ecosystem is that its large vertebrate fauna historically consisted almost entirely of birds. Apart from humans and the species they later introduced, the only native terrestrial mammals in New Zealand are bats belonging to the family Mystacinidae. As a result, birds have long played a dominant ecological role in the structure and function of New Zealand's ecosystems.

The Colourful Truffle-Like Fungi of New Zealand

Fungi represent one of the major groups of eukaryotic organisms alongside plants and animals. This kingdom includes familiar organisms such as yeasts and moulds, but also many species that produce large fruiting bodies. These larger fungi are commonly referred to as mushrooms, and the edible mushrooms people consume belong to this group.

The brightly coloured endemic truffle-like fungus of New Zealand Gallacea scleroderma（Image source：Neil Birrell， CC BY 4.0 ）

The brightly coloured endemic truffle-like fungus of New Zealand Chamonixia pachydermis（Image source：Rudolph89， CC BY-SA 3.0 ）

New Zealand possesses a remarkably rich fungal diversity. Among them are many species that produce large fruiting bodies with a truffle-like form and often display unusually bright colours.

In general, mushrooms that grow in the familiar umbrella shape disperse their reproductive spores through the air. The spores are released and carried away by wind currents. By contrast, fungi with truffle-like structures typically rely on animals for spore dispersal. Animals consume the fruiting bodies, and the spores later pass through the digestive tract and are deposited elsewhere in faeces. There are a few exceptions, such as puffballs, which release spores through air movement, but most truffle-like fungi depend on animals for dispersal.

However, typical truffles usually grow underground and rely primarily on scent to attract mammals that dig them up and eat them. They also tend to have dull colours. In contrast, many of New Zealand's truffle-like fungi grow above ground and display vivid coloration. Because New Zealand's terrestrial ecosystem historically lacked native land mammals and was instead dominated by birds, scientists have hypothesized that these colourful fungi may have evolved to attract birds capable of seeing bright colours, thereby allowing birds to assist in dispersing their spores.

Unfortunately, direct observations of New Zealand birds consuming truffle-like fungi are extremely rare.

Extinction and the Idea of Evolutionary Anachronism

Statistical studies indicate that since human settlement began in New Zealand during the thirteenth century, approximately 41 percent of the country's native land bird species have gone extinct. This raises the possibility that the primary fungal-eating birds may themselves have disappeared.

This type of situation is not unusual in evolutionary history. A well-known example involves avocados, whose large fruits are believed to have originally been dispersed by giant ground sloths that are now extinct. Such cases are known as evolutionary anachronisms. The concept refers to traits that evolved through interactions between species but later became maladaptive or puzzling after one of the interacting species vanished.

In other words, two species may evolve traits that benefit their mutual relationship, yet once one partner disappears, the traits of the other may appear mismatched to the modern ecosystem.

A New Study

In several locations on New Zealand's South Island, researchers have discovered hundreds of fossilized bird droppings known as coprolites. Analyses have shown that most of these coprolites were produced by five extinct species of moa as well as the endangered kākāpō.

To investigate whether fungal-eating birds might have belonged to extinct species, researchers selected two coprolites identified as belonging to the upland moa, Megalapteryx didinus, for detailed study.

Reconstruction of the upland moa（Image source：George Edward Lodge，CC0 1.0 ）

Fossil skeleton of the upland moa（Image source：Te Papa - Museum of New Zealand， CC BY 4.0 ）

By analyzing fungal DNA preserved within these coprolites and examining the morphology of spores under the microscope, the researchers identified tissues belonging to several species of New Zealand truffle-like fungi. In addition, the spores were present at extremely high concentrations, indicating that the birds that produced these droppings had consumed the fruiting bodies of these fungi.

A previous study had also detected fungal DNA in moa coprolites, but spores were not found in that earlier work. The new study therefore provides crucial additional evidence confirming that moa consumed these fungi.

Because moa species generally had broad and overlapping diets, the researchers suggest that other moa species likely consumed fungi as well. Nevertheless, more coprolites will need to be examined in future studies to confirm this hypothesis.

Ecological Consequences

Beyond revealing an ecological interaction between moa and fungi, the study also points toward deeper ecological implications. It may represent the beginning of a long-term transformation within New Zealand's ecosystems.

Compared with other New Zealand birds, moa likely had much larger home ranges and longer digestive retention times. This means that spores consumed by moa could have been transported and deposited far from the original source.

Researchers have also determined that many of these truffle-like fungi are not decomposers. Instead, they form mutualistic relationships with forest trees such as the New Zealand endemic silver beech, Lophozonia menziesii. These fungi belong to ectomycorrhizal groups that form symbiotic associations with plant roots, helping trees obtain nutrients from the soil. Consequently, these fungi play a crucial role in maintaining the health of native forests.

Silver beech (Lophozonia menziesii)（Image source：Krzysztof Golik， CC BY-SA 4.0 ）

After the extinction of moa, some bird species still consume these fungi and disperse their spores. However, these remaining birds are far less effective dispersers. Their smaller body size, shorter gut retention times, and more limited movement ranges reduce their ability to spread fungal spores across large distances.

Over time, this reduced dispersal may cause native fungal populations to decline, which could in turn weaken the health and regeneration of native forests. Although current forests have not yet shown dramatic declines linked to this process, researchers warn that long-term ecological effects may eventually become visible.

The situation is further complicated by the introduction of foreign mammals and fungi by humans. Many of these mammals preferentially consume introduced fungal species. Even when they eat native fungi, the spores often fail to survive passage through the mammalian digestive system.

As a result, mammals primarily disperse non-native fungi rather than native ones. These introduced fungi may then facilitate the establishment of non-native tree species, potentially paving the way for the gradual replacement of native forests by forests dominated by exotic species.

The End

Although many examples of evolutionary anachronism have previously been documented, most involve plants and animals. This study represents one of the rare cases demonstrating that fungi can also be affected by the loss of their evolutionary partners.

An ecosystem is typically composed of thousands of interconnected species. When one or more species disappear, the consequences can cascade through the entire ecological network. Because human activities have dramatically accelerated species extinctions, evolutionary anachronisms are likely becoming increasingly common.

In some cases, introduced species or human activities may partially replace lost ecological partners. In most situations, however, such replacements are incomplete or ineffective. The long-term ecological effects of species loss are therefore gradually emerging in ecosystems around the world.

For this reason, careful and proactive ecological conservation will become increasingly important in the future.

Author: Bai Leng

Reference:

Boast, A. P., Wood, J. R., Cooper, J., Bolstridge, N., Perry, G. L. W., Wilmshurst, J. M. (2025). DNA and spores from coprolites reveal that colourful truffle-like fungi endemic to New Zealand were consumed by extinct moa (Dinornithiformes). Biology Letters

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