At issue are 250 or so "candidate species," a designation that offers no legal protections for affected species and is intended to be temporary. But nearly 100 species have been on the ESA waiting list for more than 10 years, and 73 have been waiting more than 25 years, according to the Center for Biological Diversity, an advocacy group.
The group has sued the Interior Department in U.S. District Court for the District of Columbia over its use of the candidate species list, saying the government's failure to promptly decide on listings violates the species law.
The law says Interior must issue a "finding" -- a decision on whether a species deserves a listing -- 12 months from its receipt of a listing petition. But petitions are going unanswered for an average of 11 years, the center says, and often are not addressed until forced by a judicial order.
The Obama administration says it is going to change how candidate species are handled. The Fish and Wildlife Service, the Interior agency responsible for the management of endangered species, is working on an accelerated listing process, said Doug Krofta, the service's listing chief. With new techniques and more funding, Krofta said, the service can trim the candidate list by 25 percent by the end of 2010.
"I think we're getting closer to ... getting that 12-month finding within 12 months," Krofta said. "If you were to give me a petition now ... I'll likely be able to respond within a year. Where we were a couple years ago, it would be four to five to six years."
The service is planning to attack the backlog on two fronts.
First, it plans to focus on sweeping, ecosystem-based listings that would address many species at a time. And second, it is putting more money into the endangered species program. The budget has more than doubled since early in the Bush administration, going from $9 million in 2002 to $19 million in fiscal 2009.
But environmentalists say the funding boost is far from what is needed to clear the candidate species backlog: $153 million over five years.
Noah Greenwald of the Center for Biological Diversity maintains that funding for the program should be doubled again to allow the Fish and Wildlife Service to keep pace with new listing petitions while reducing its backlog.
"I think we've only scratched the surface of the problem," Greenwald said, "and it is going to require more resources as time goes on to save species from extinction."
In part, the service's move toward ecosystem-based listings is an attempt to save money on listings while trying to bolster conservation of several imperiled species at a time.
The idea is to cluster multiple species from an ecosystem into a single ESA listing, instead of going species by species, the traditional approach.
Overall, federal biologists say, the strategy allows for the management of an entire ecosystem, rather than going species by species. It also condenses the listing process for many plants and animals into one proposal.
Sam Hamilton, the Fish and Wildlife Service's new director, said following his Senate confirmation hearing in July that he would "get deeply immersed in" addressing the backlog. Ecosystems-based listings, he added, were among the tools he would use for that job.