“The Kirtland’s warbler has required protections for as long as there has been an Endangered Species Act (ESA), but that’s about to change.”
“In 1971, two years before enactment of the ESA, the Kirtland’s warbler population declined to approximately 201 singing males and was restricted to six counties in the northern part of Michigan’s Lower Peninsula.”
“By 2015, the year of the last full census, the population reached a record high of 2,383 singing males and had spread geographically. FWS noted that the “frequent, loud, and persistent singing of territorial males during the breeding season” made counting possible.”
View the whole story here: https://www.sciencemag.org/news/2019/10/after-50-year-conservation-effort-songbird-flies-us-endangered-species-list