How long recovery takes depends on how much a species has declined, how much natural habitat remains, whether the causes of the species' decline are understood and can be controlled easily, how long that species takes to mature and reproduce, and other factors. More than half of listed species are plants. The current population trend of about 23 percent of listed species is uncertain. As funding permits the Fish and Wildlife Service is conducting surveys to determine the status of species whose current population trend is uncertain. Beattie said critics of the Endangered Species Act often cite the difficulty and cost of recovering species.
Recovery is like emergency room medicine.
It costs more than seeing your regular doctor for preventive care. And it costs more than seeing your regular doctor for preventive care. And it costs more to recover endangered species than it would have cost to prevent their decline in the first place. Nevertheless, I doubt a single American would say that saving the bald eagle wasn't worth the time or money. That's about the cost of building one mile of urban highway.