The hidden ecological cost of an invasive fruit tree

Nature · Published 19 October 2026 · Updated 20 October 2026 Swipe more like this →

In short: In the forests of Mauritius, a single invasive species is quietly dismantling the island's natural regeneration system. While it may look like a lush woodland, the Strawberry Guava is creating a biological barrier that prevents native birds from performing their vital role as seed dispersers.

Researchers comparing weeded and invaded forests in Mauritius found that the presence of Strawberry Guava (Psidium cattleyanum) significantly weakens bird-plant interactions. In weeded areas—where invasive plants were removed starting in the 1990s—birds attacked fruit models at rates about three times higher than in invaded forests. This suggests that the invasive plant is not just occupying space but actively degrading the habitat quality for native frugivorous birds.

The decline in bird activity is likely driven by two primary mechanisms. First, native fleshy-fruited plants produce fewer fruits in invaded zones. Second, the extremely high stem density of understorey weeds may physically hinder forest penetrability, making it harder for birds to navigate and forage. This disruption is critical because these birds are essential for dispersing seeds and facilitating the natural regeneration of the forest.

The scale of the problem is significant: while 8% of surviving natural habitats have been weeded, the remaining 92% continue to be degraded by invasive species. Conservationists argue that prioritizing in situ control of these plants is more sustainable than costly manual planting. By restoring the carrying capacity for native birds, the ecosystem can regain its resilience and naturally regenerate the native flora.

This ecological struggle mirrors the broader history of Mauritius, which has transitioned from a sugar-dependent economy to a diversified upper-middle-income nation. However, the island's biodiversity remains under pressure, highlighting the need for integrated conservation strategies that protect both the economic and biological integrity of the nation.

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