As a college student, she spent a summer at Aberdeen Proving Grounds, where she released peregrine falcons back into the wild as part of a national recovery effort.

Twenty years later, as the director of the United States Fish and Wildlife Service, she officially removed them from the federal list of endangered species due to the successful recovery efforts,[7] in which she participated.

[14] The Service was involved in many successful efforts to recover imperiled wildlife during her tenure, including the bald eagle,[15] gray wolf[16] and the Aleutian Canada goose.

[20] Under her tenure, Defenders has played a key role in the reintroduction of bison to tribal reservations,[21][22] secured protections for right whales,[23][24] sea turtles and piping plovers[25] and many other species and habitats.

Clark refused to voluntarily recognize the union, Defenders United,[31] triggering an election sponsored by the National Labor Relations Board (NLRB) in 2021.

[32][33] Matters worsened in 2022; according to an article by to Politico, “current and former staff blame Defenders CEO Jamie Rappaport Clark for setting the tone and establishing a ‘culture of fear’ within the organization.

[39][40] In protest of these violations, the staff union held a 3 day rally in front of Defenders HQ in Washington, DC, and issued a public petition in February 2023 calling for Clark to negotiate a fair contract or resign as CEO, which garnered over 500 signatures.