On the remote Palmyra Atoll in the Pacific Ocean, more than a thousand miles south of Hawaii, scientists have discovered an unexpected link between seabirds and the health of coral reefs.
Birds such as red-footed boobies and white terns feed at sea and return to land. There they leave guano — a nitrogen-rich fertilizer that nourishes the forest and, with the rain, washes into the ocean.
These nutrients stimulate the growth of plankton, sustain fish and even help corals. Reefs near bird colonies turn out to be noticeably healthier.
A study of nearly two hundred atolls showed that birds return more than a hundred thousand pounds of nitrogen to land each year. This is a natural cycle that makes tropical islands and reefs centers of biodiversity.
However, on many islands this link has been broken. Invasive rats and coconut palm plantations have reduced bird populations, and with them the flow of nutrients into the water.
On Palmyra, restoration has been under way for more than ten years: in 2011 the rats were eradicated, and since 2019 more than a million coconut palms have been removed. The forest is returning, and the birds are nesting more actively.
“Guano nourishes the ecosystem from the tropical forest to the reef, and we simply want more guano,” says Katie Franklin of The Nature Conservancy.
Alex Wegmann, the organization's lead scientist, notes that if local threats are removed, ecosystems often recover on their own and adapt better to climate change.
Could the return of the birds become one of the keys to saving reefs in a warming ocean?
Palmyra's experience is already being applied on other atolls, including the Chagos Archipelago in the Indian Ocean. Restoring birds helps not only the reefs but the entire interconnected ecosystem.
