漂流者 22

Almost all animal castaways would have died of exposure, hunger or thirst

long before reaching French Polynesia in the eastern Pacific

Reaching land here was a matter of extraordinary luck

Unlike Fiji,

there are no bats in French Polynesia,no frogs and only a handful of lizards

The most successful travellers were the long-haul fliers - sooty terns

Incredibly,

they can stay in the air for four years without landing

But to breed, they must return to nesting sites on remote islands

And when they do,

they introduce new life

Sticky or barbed seeds fasten on to their feathers

and hitch rides across oceans

On some islands, 75% of plants arrived with the birds

Seeds are even carried in the stomachs of some birds

As if getting a lift wasn't enough for these seeds,

seabirds also provide them with something else

The seafood these birds bring back to the islands

is turned into nutrient-rich guano - plant fertiliser

And there's enough of it to transform barren coral atolls into fertile groves