How lizards help keep Madagascar's forests alive

In the forests of Madagascar, small lizards do more than sunbathe on rocks or snap at insects. In fact, they may be shaping the future of Madagascar’s forests, one seed at a time.

Madagascar has long fascinated scientists, naturalists, and explorers alike. This large Indian Ocean island is home to some of the world’s rarest species. More than 80% of its wildlife can’t be found anywhere else. Lemurs leap through treetops. Baobabs rise like ancient towers. Orchids bloom in forests untouched for centuries. The island is a living archive of evolution’s creativity.

Its uniqueness stems from a deep, ancient break. Around 88 million years ago, Madagascar drifted away from India. Once separated, its ecosystems evolved in isolation. As generations passed, this seclusion led to extraordinary biodiversity. But amid all the celebrated species and stories, silent helpers have gone unnoticed for too long: the lizards.

How lizards spread seeds in forests

Many plants don’t just drop seeds nearby. They depend on animals to move them across the land. This natural process, called endozoochory, involves an animal eating fruit or seeds. Later, those seeds get expelled in the animal’s droppings. Carried far from the parent plant, the seeds land in fresh ground, ready to sprout.

Most of what we know about endozoochory comes from studying mammals and birds. Lemurs, for example, are known for their role in this cycle in Madagascar. Birds also help, flying great distances and spreading seeds with every flight. But reptiles, particularly lizards, haven’t received the same attention.

That’s a mistake, say researchers at Kyoto University. They argue that lizards have an important part to play too. These animals may not be classic fruit-lovers, but a few species do consume fruits and other plant parts. Their habits, movement, and resilience may allow them to serve as crucial seed dispersers in ways we’ve only just begun to understand.

Why lizards matter in forest ecosystems

Unlike lemurs or fruit bats, most lizards don’t depend on fruit. Less than 10% of lizard species are considered frugivores. Yet those that do eat fruit may influence plant life in ways researchers are only now beginning to measure. Some species even serve as primary seed dispersers for specific plants, especially in areas where larger animals have disappeared.

“Lizards are under-appreciated as seed dispersers in many forest ecosystems, but we hypothesized that they may play a more important role across a broader range of regions than previously recognized,” said corresponding author Ryobu Fukuyama.

To test this idea, Fukuyama and his colleagues designed a study focused on three lizard species in Madagascar. These were the Malagasy Giant Chameleon, Cuvier’s Madagascar Swift, and the Western Girdled Lizard.

All three species are omnivorous and known to eat fruit occasionally. However, their potential as seed spreaders had never been seriously evaluated.

Observing lizard behavior

The team set up camp in a tropical dry forest in Madagascar. They watched the lizards carefully, recorded their feeding behavior, and collected fecal samples.

They also ran germination tests to see if the seeds could still grow after passing through a lizard’s gut. This detailed approach helped them track not just what lizards eat, but what they contribute to the ecosystem.

Their findings surprised them. The lizards consumed fruits from more than 20 different plant species. Even more interesting, these plants were often not the same ones favored by lemurs. This suggested that lizards might not just support the same trees as other animals. They might help expand the forest’s botanical diversity.

Fecal analyses confirmed that many seeds remained viable. The lizards were not just accidental consumers. They acted as functioning carriers in the seed cycle, allowing new plants to take root away from their original source.

How lizards help forests recover

Madagascar’s forests face serious threats. Logging, slash-and-burn farming, and habitat destruction have left scars across the landscape. As forests shrink, large fruit-eaters like lemurs lose their homes. When they vanish, the trees that rely on them struggle to reproduce.

But lizards are survivors. They adapt to disturbed environments. Where lemurs falter, these reptiles often continue to thrive. That adaptability may give them a vital role in the regrowth of damaged forests. As long as they keep consuming fruit and dispersing seeds, they could help heal the land.

Their contributions might not replace larger animals completely. But they offer hope for certain plant species that would otherwise vanish. In places where biodiversity is already under pressure, every small helper matters.

What we still don’t know

The Kyoto University team views this study as only the beginning. They’ve revealed that lizards do eat fruit and spread seeds. But many questions remain. How far do these lizards travel? Do they prefer certain plants over others? Can they truly support forest restoration over time?

“Although lizards in Madagascar consume fruits from many plant species, other aspects of their role as seed dispersers, such as dispersal distances, remain poorly understood,” commented Fukuyama.

Future research will explore these unknowns. Understanding dispersal distance, for instance, will help determine how effective lizards really are in forest regeneration. Scientists also want to study whether lizard seed dispersal supports tree diversity, or whether it favors only a few resilient species.

A new way to look at old forests

Madagascar’s ecological story is still unfolding. Its forests, once dense and vibrant, now face an uncertain future. Conservation efforts often focus on charismatic animals, the ones we notice first. Lemurs, chameleons, and rare orchids get headlines. But the lizards, often silent and unnoticed, may be doing more than we imagined.

They offer us a chance to rethink how forests work. Even in the most unexpected corners of nature, there are creatures playing vital roles. By understanding them better, we can protect not only individual species but the living systems that keep our planet healthy.

The study is published in the journal Biotropica.

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