Rare Crow Faces Extinction in 75 Years
Photo credit: Wikimedia Commons
The Mariana crow, native to Rota Island in the western Pacific Ocean, could become extinct in 75 years—nearly twice as fast as conservationists had previously estimated. The problem, a new study suggests, is that the mortality rate among juvenile birds—recently estimated at nearly 40 percent—is much higher than earlier estimates.
As dire as this new estimate seems, it is not entirely a death sentence for the species. Indeed, the new insight may provide a clue that could help save the crow from extinction.READ MORE: 7 Weird and Wacky Endangered Birds
James Ha, a research associate professor at the University of Washington, explained:
It's the first year of survival that's the most crucial...if only 40 percent of fledglings survive their first year, then we predict the species will go extinct in 75 years.
The estimate uses a model based on the current population of the Mariana crow—330 individuals—and the 40 percent first-year survival rate. It also incorporates the average number of fledglings per nest and data on the fertility of female birds.
Using this model, Ha estimates a population of 90 birds in 20 years and completely extinct within 75 years.
At the same time, the model was able to predict the threshold the birds would have to achieve to survive. By increasing the first-year survival rate, the shrinking of the population slows and eventually stabilizes.
"According to the population model," Ha said, "if we can boost fledgling survival from 40 percent to 70 percent, the Mariana crows will be fine."
Now it is up to conservationists to figure out how this crucial number can be increased.