Concerns are being raised about the declining population of the Marianas Crow birds on Rota, which if continues, would see the bird disappear for good.
The crow is found only on Rota and Guam.
Past surveys by the US Pacific Islands Fish and Wildlife, found just over one thousand crows on Rota in 1982, but that dropped to just under 600 crows by the mid nineties.
Wildlife biologist, Suzanne Medina, says now there are under 200 crows left on Rota.
She says the brown tree snake is largely to blame for bird's demise on Guam, with only two male crows left now.
But Birdlife International's senior technical adviser for Pacific, Mark O'Brien, says more research is needed.
"It is, yes it is critically endangered. It's not entirely clear exactly why its declining on Rota, could be to do with habitat change, it could be to do with other things. But it's certainly different as to why it's declined on Guam, there's no real evidence of snakes having any real impact on Rota."
Birdlife International Pacific's, Mark O'Brien.