Rasmussen is a visiting assistant professor of zoology, and assistant museum curator of mammalogy and ornithology, at Michigan State University (MSU), having formerly been a research associate for the eminent American ornithologist S. Dillon Ripley at the Smithsonian Institution in Washington, D.C. She is a member of the American Ornithological Society (AOS) North American Classification Committee (NACC), a scientific associate with the bird group of the British Natural History Museum zoology section at Tring, and an associate editor of "The Ibis", the scientific journal of the British Ornithologists' Union. She is a scientific affiliate for the Field Museum of Natural History and the founder and editor of AVoCet, MSU's avian vocalizations center. In 2020 she replaced the ornithologist Frank Gill as an editor of the "IOC World Bird List", an online list maintained on behalf of the International Ornithologists' Union.