Delisting the Interior Least Tern

PROJECTED 20:1 RETURN ON INVESTMENT OVER THE NEXT 10 YEARS

Interior Least Terns (ILT) are colonial, fish-eating birds that breed and nest on sand bars within active channels of large sand bed rivers of the Great Plains and in the Lower Mississippi River Valley. The species was listed as endangered in 1985. The Corps spends about $240 million annually on the conservation, management and compliance for species protected by the Endangered Species Act (ESA), including nearly $6 million annually since 2005 on conservation and compliance for the ILT population. Through research funded by the Corps’ Dredging Operations and Environmental Research Program, the ILT was removed from ESA protection, which is expected to save approximately $4 million per year over the next 10 years in dredging and placement costs.

PROBLEM: The Corps has spent nearly $6 million annually since 2005 (more than $79 million total) on conservation and compliance for federally endangered Interior population of Least Terns (ILT) that breed and nest on interior river sandbars. The impacts span multiple civil works missions and cover many projects across multiple Corps divisions and districts.

SOLUTION: The Dredging Operations and Environmental Research (DOER) program and ERDC scientists led a 10-year collaboration with American Bird Conservancy, the U.S. Fish and Wildlife Service, and Corps divisions and districts to support ILT recovery and delisting. DOER supported a rangewide survey, developed a range-wide ILT meta-population model to evaluate population persistence across a number of management scenarios, and collaborated on conservation plans and a cost-effective post-listing monitoring plan.

IMPACT: In October 2019, the U.S. Fish and Wildlife Service published a draft rule to remove the ILT from Endangered Species Act protection. With an approximately $2 million research investment from DOER over a 10-year period, delisting will produce lower operational expenditures and increased mission and operational flexibility. The projected return on investment for the $2 million research commitment is expected to be 20:1 over the next 10 years.