As the decade draws to a close, one little reptile is going out on a high. After 37 years as an endangered species, the Monito gecko has finally received a new, official distinction: recovered.
The inch-and-a-half-long gecko, endemic to a single tiny island in Puerto Rico, is one of three formerly endangered species to hit that milestone this year. The others—the Kirtland’s warbler, a petite, chartreuse-bellied songbird, and the Foskett’s speckled dace, a spotted minnow native to two springs in Oregon—join the gecko to become the 25th, 26th and 27th U.S. animal species in history to make it successfully off the Endangered Species Act’s list.
The list of 27 (plus specific recovered populations of an additional five animal species) is modest when put into context. Since the Endangered Species Act took effect in 1973, 719 animal species native to the U.S. have been declared threatened or endangered under the law. Of those, some, such as the Caribbean monk seal, have subsequently been declared extinct. The rest remain on the list—federally protected, but still imperiled. (See a different endangered animal in every U.S. state in this interactive map.)
The process of taking a species off the list, called delisting, is complex. Recovery can be lengthy in the best of circumstances and impossible in the worst. But when it happens, sometimes through decades of effort, it signals conservation triumph manifesting the full intent of the Endangered Species Act: the ability not just to protect animals, but to actually bring them back from the brink.
The Monito gecko had a few things going for it: Scientists knew exactly why it was endangered (invasive predatory rats), they had a pretty good guess of how to help it (get rid of the rats), and the entire species was contained to a single, 40-acre rock.
Between 1992 and 1999, the U.S. Fish and Wildlife Service’s Caribbean field office led two separate rat eradication campaigns, using poison that attracted the rats but not the geckos. It worked. By 2014, experts found Monito island to be rat-free, and the gecko population seemed to have rebounded. In 2016, they did a formal population assessment, estimating that about 7,600 geckos lived on the island.
“The Monito gecko is a pretty good example of the [recovery] process going well,” says Noah Greenwald, the endangered species director at the Center for Biological Diversity, a nonprofit conservatio