The Fish and Wildlife Service warned that climate change, combined with other environmental pressures, could make such disappearances more common. As an example, it said nearly 3 billion birds have been lost in North America since 1970. 鱼类和野生动植物局警告说，气候变化与其他环境压力相结合，可能会使这种失踪更为普遍。 例如，它说自1970年以来，北美已经丢失了近30亿只鸟。

“These extinctions highlight the need to take action to prevent further losses,” the agency said in a statement. 该机构在一份声明中说：“这些灭绝强调了采取行动以防止进一步损失的必要性。” 

Around the world, about 900 species have been documented as extinct. The actual number, however, is thought to be much higher because some are never officially identified. Many scientists have warned that the planet is in an “extinction crisis,” with plants and animals disappearing at 1,000 times the historical rate. 在世界范围内，大约有900种被记录为灭绝。 但是，实际数字被认为要高得多，因为有些人从未正式识别出来。 许多科学家警告说，地球正处于“灭绝危机”，动植物的消失是历史速度的1000倍。 

Several scientists said it was possible that one or more of the 23 species included could reappear in the future. 几位科学家说，未来包含的23种物种中有一个或多个可能会重新出现。 

Cornell University bird biologist John Fitzpatrick is a leading figure in the hunt for the ivory-billed woodpecker. He told The Associated Press he thinks it was too early to declare the birds extinct. “Little is gained and much is lost” he said of the declaration process. 康奈尔大学鸟类生物学家约翰·菲茨帕特里克（John Fitzpatrick）是寻找象牙嘴啄木鸟的领先人物。 他告诉美联社，他认为宣布鸟类灭绝还为时过早。 他谈到宣言过程时说：“几乎没有收获，损失了很多。

”Fitzpatrick led a 2005 study that claimed the woodpecker had been rediscovered in eastern Arkansas. He said removing a species from the ESA reduces public attention that is needed to help continue environmental protection efforts. 菲茨帕特里克（Fitzpatrick）领导了一项2005年的研究，该研究声称啄木鸟在阿肯色州东部重新发现。 他说，从ESA中取出一种物种可以减少公众的关注，以帮助继续环境保护工作。 

Officials said the extinction declarations were driven by a desire to clear a backlog of suggested changes for species that had not been acted upon for years. They hope this will free up resources for more protection efforts for species that still have a chance for recovery. 官员们说，灭绝声明是出于渴望清除积压的对物种的积压，这些变化多年来一直没有采取任何行动。 他们希望这将为仍然有恢复机会的物种提供更多保护的资源。