Is Vostok Island a black hole in the Pacific Ocean? No, but for some migratory birds, it might as well be — there is no escape.
One Redditor instigated a partial internet breakage when he posted a Google Earth screenshot of the island in 2021. The 22-hectare speck, which is part of the property of Kiribati, appears on Google Maps as virtually black.
But it’s not an underworld portal or a secret military base. The black appearance has been widely reported as an optical illusion, caused by Vostok’s dense forest when photographed from low orbit.
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Still, the uninhabited outcrop isn’t your everyday coral dot in the south Pacific. That’s because it’s home to a certain type of forest that can fatally trap birds like a huge, sticky net.
Black noddy terns nesting in pisonia trees on Australia’s Lady Musgrove Island. Photo: Shutterstock
The pisonia tree grows in close copses at heights up to 30 meters. According to JSTOR, it’s not uncommon for groves of pisonias to outcompete everything else trying to grow around and under it.
Canopy of pisonias. Photo: USFWS via Flickr
None of this would be a particular problem for tree-dwelling birds if pisonias didn’t also produce long, velcro-like seeds that secrete a gooey membrane.
For nesting colonies of seabirds like white terns, lesser noddies, and red-footed boobies, outcomes can be grim. If even a few pisonia seeds stick to a bird, they can ground it. Restricted from flight, the bird can starve to death. Birds can even get “mummified” in the canopy if they run into an especially thick spot.
A pisonia seed. Photo: Scott Zona via Flickr
Researchers look at the grisly situation as a zero-sum evolutionary game. The pisonias need to spread to other islands to expand their range. The birds need somewhere to nest. Birds don’t eat pisonia seeds, and seeds attached to carcasses in studies didn’t germinate any better than normally-planted ones.
At the same time, the trees apparently don’t kill the birds at a high enough rate to trigger an adaptation.
Vostok Island may not be a black hole — but it certainly is a standoff.
