More than a century after the catastrophic 1883 volcanic eruption stripped the Krakatau islands in the Sunda Strait of nearly all life, dense forests have reclaimed the physical terrain not merely through wind-borne plant regeneration, but largely because fruit bats and birds carried seeds across the water, Suara.com reported.
Historical Research on Plant Colonization From 1883 to 1992
The extent of this animal-driven recovery emerged from historical records and field surveys spanning nearly a hundred years. Robert J. Whittaker and Stephen H. Jones of the University of Oxford published their findings in the Journal of Biogeography in 1994, tracing how vegetation returned after the cataclysmic event. The researchers identified 124 plant species that likely spread after animals ingested and later excreted the seeds. An additional 49 species received similar transport assistance from wildlife.
When accounting for all animal vectors, the total reaches 173 species, representing approximately 42 percent of all flowering plants on Krakatau. Viv.co.id also covered the study, noting that the close proximity of the islands—sitting only about 40 kilometers from Java and Sumatra—allowed birds and bats to bridge the gap from the mainland.
Early Savanna Transition to Forest Canopy by the 1920s
Vegetation looked starkly different during the early decades of the twentieth century. Grasslands and open savannas initially dominated the terrain before individual shrubs and trees began clustering together to form a closed canopy. Botanical records compiled by Docters van Leeuwen and cited in the Oxford study indicate that this forest formation happened rapidly, nearing completion by the end of the 1920s.
Ficus trees, commonly known as figs, proved especially adept at colonizing the harsh environment. Researchers cataloged 24 Ficus species across the islands, with 13 of those varieties known to rely on bats for seed dispersal. Fruit bats drop or evacuate seeds through feces and regurgitation as they forage across different zones. Records show fruit bat species such as Cynopterus sphinx present on Krakatau since 1919. Later, surveys on Sertung Island in 1985 located a large colony of flying foxes, or Pteropus vampyrus, which expanded to more than 600 individuals four years later.
Complementary Seed Dispersal Roles of Bats and Pigeons
Birds shared the workload by transporting larger flora between isolated landmasses. Pigeons and doves, specifically imperial pigeons from the genus Ducula, handled heavier seeds that smaller animals could not lift. Whittaker and Jones concluded that birds and bats performed complementary functions in restoring the ecosystem by targeting different plant traits.
Those insights offer practical blueprints for modern habitat restoration projects on degraded lands. Scientists suggest planting small clusters of fruit-bearing trees and shrubs to draw in bats and birds, which then act as natural agents to spread seeds outward into wider deforested zones. Successful restoration, however, still requires active habitat protection, strict wildfire prevention, and safeguards for the wildlife populations responsible for carrying the seeds.
