The likely extinction of two South Florida butterflies never declared endangered points up the importance of protecting rare species, conservationists say. Florida Zestos and rockland grass skippers were declared officially extinct by the U.S. Fish and Wildlife Service this week -- but they might not have been had they been granted protection under the Endangered Species Act, the Center for Biodiversity said Friday in a release. \"We didn\'t have to lose these two butterflies,\" said Jaclyn Lopez, a Florida-based attorney with the Center for Biological Diversity. \"Their extinction is a stark reminder that the ability of the Endangered Species Act to save species is limited only by our choice to use it.\" The Fish and Wildlife Service indicated the butterflies likely went extinct because of habitat loss caused when coastal development prevents species\' landward retreat from rising sea levels resulting from climate change, the center said. Fish and Wildlife recently proposed Endangered Species Act protection for other Florida species -- three Florida plants and the Florida bonneted bat, which are threatened by rising sea levels, the center said. The proposal to protect the species was part of a settlement between the FWS and the Center for Biological Diversity requiring expedited decisions on protection for 757 species nationwide. \"The important thing about our agreement with the service is that [it] requires the agency to follow the law and make decisions about protecting imperiled species before it\'s too late for those species,\" Lopez said. \"The loss of these two butterflies drives home the point: Once these animals are lost, they\'re lost forever.\"