Analysis: 85 Percent of Continental U.S. Birds Protected by Endangered Species Act Have Increased or Stabilized Since Being Protected

Eighty-five percent of continental United States birds protected under the Endangered Species Act increased or stabilized their population size since being protected, according to a new report by the Center for Biological Diversity. The average population increase was 624 percent.

A Wild Success: A Systematic Review of Bird Recovery Under the Endangered Species Act is the first-ever study to examine the year-by-year population size of all 120 bird species protected under the Endangered Species Act. Drawing on more than 1,800 scientific population surveys, the analysis concludes that the Act has recovered imperiled birds at the rate and magnitude intended by its congressional creators and administrative overseers.

"The Endangered Species Act has been spectacularly successful for America's most imperiled birds," said Loyal Mehrhoff, the Center's endangered species recovery director. "From plovers on the East Coast, to warblers in the Great Lakes, terns in the Midwest, falcons in Texas, bald eagles in the Rocky Mountains, and towhees in California, the Endangered Species Act has rapidly and dramatically increased bird population sizes and put these birds on the road to full recovery."

Recovering species include California condors in California and Arizona (up 391 percent since 1968), whooping cranes in the central United States (up 923 percent since 1967), wood storks in the Southeast (up 61 percent since 1984), Kirtland's warblers in the Great Lakes (up 1,077 percent since 1971), California least terns (up 1,835 percent since 1970) and Puerto Rican parrots (up 354 percent since 1967).

Key findings of the report:

• 85 percent of continental U.S. birds increased their population size or stabilized since being protected under the Endangered Species Act.
• The average population increase was 624 percent.
• 61 percent of Pacific Island (Hawaii, Guam, Palau and the Commonwealth of the Northern Marianna Islands) birds have increased their population size or stabilized since being protected under the Endangered Species Act. The weaker performance is due to lower funding levels, smaller population sizes at the time of Endangered Species Act listing, and more species being threatened by difficult to manage invasive predators and diseases.
• Few birds were expected to recover by 2015 because they have been protected under the Act for just 36 years on average, while their federal recovery plans estimate 63 years is needed.
• Birds are recovering at the rate expected by federal recovery plans.
• Endangered birds fared much better than unprotected birds, which on average declined 24 percent since 1974. This is because endangered birds are being actively managed, while common birds generally are not.

"The Endangered Species Act not only greatly increased bird population sizes, it benefited thousands of other species, people and entire ecosystems," said Mehrhoff. "In recovering imperiled birds, federal and state wildlife agencies cleaned up America's rivers and lakes, restored millions of acres of forest, kept development away from public beaches and greatly expanded the size of, and access to, public lands."

Among the birds in today's report:

California condor -- America's largest bird, with a wingspan of almost 10 feet, was protected as endangered in 1967 after DDT, lead poisoning and shootings pushed it to the brink of extinction. By 1968 only 55 birds survived in the wild. Due to intensive recovery work, by 2015, 270 birds were living in three wild populations -- two in California and one in the Grand Canyon -- and 167 were safe in captivity.

Whooping crane -- By the time America's tallest bird was protected as endangered in 1967, unregulated hunting and habitat destruction had crashed its population to just 43 individuals in the wild and seven captive birds. Intensive conservation efforts, including the designation and protection of critical habitat areas in Kansas, Nebraska and Oklahoma, helped the population increase to 440 wild and 161 captive birds by 2014.

Wood stork -- The draining and damming of the Southeast's rivers, wetlands and swamps caused this large wading bird to decline from 20,000 pairs in the 1930s to only 29 nesting colonies when it was listed as endangered in1984. Due to habitat restoration and the purchasing of vital wetlands, the wood stork was downlisted to "threatened" status in 2014 and by 2015 had increased to more than 10,000 nesting pairs.

Read more in the report and about other Endangered Species Act successes here.