The current population of the island scrub jay, a rare California bird, is only a fifth of what experts had previously believed, a new study reveals.
The island scrub jay is a brightly colored blue and gray bird that is only found on Santa Cruz Island, about 17 miles off the coast, south of Santa Barbara.
The study was led by the Smithsonian Institution's Migratory Bird Center in Washington, D.C., and published in the journal Ecological Applications. According to its findings, the island scrub jay is one of the rarest birds in the United States, even though its population has increased in recent years.
"The bad news is that we only have about 2,500 of these birds left, a very small number for any species," says Dr. Scott Sillett, lead author of the study and part of the Smithsonian's Migratory Bird Center. "The good news is that we are seeing an increasing population trend. It appears that there has been about a 20 to 30 percent population increase in the last 25 years owing to a series of conservation actions on the island."
The study says that the island scrub jay has a population size similar to or less than that of other species currently listed as threatened or endangered in the United States. As a result of this study, the International Union for the Conservation of Nature has raised the threat level for the species from "near threatened" to "vulnerable to extinction." However, neither the federal government nor the state of California has listed the species as threatened.
Mike Parr, vice president of American Bird Conservancy, one of the nation's leading bird conservation organizations, says he hoped the study would prompt both the federal government and California to consider new protections for the island scrub-jay "in short order."
"Whenever a species only exists in small numbers in a singular location, it is cause for concern," Parr says. "That concern is heightened when the location in question is a relatively small island. Islands are especially vulnerable to introduced predators, severe weather and climate change impacts that could threaten the survival of this bird."
The authors of the study are taking a cautiously optimistic stance toward the future for the island scrub jay, noting that the entire range of the bird is protected in Channel Islands National Park. Nevertheless, researchers say, the population estimates, coupled with the species' restricted range and low diversity underscore the bird's vulnerability to natural disasters and West Nile virus."
The island scrub jay has never been reliably documented anywhere but on Santa Cruz Island.
American Bird Conservancy is a not-for-profit membership organization whose mission is to conserve native birds and their habitats throughout the Americas. The conservancy acts by safeguarding the rarest species, conserving and restoring habitats, and reducing threats, while building capacity in the bird conservation movement.