Sievert Rohwer is one of the most productive, insightful, and influential researchers in ornithology. His work has been a model blend of field, museum, and laboratory studies integrated in a theoretical context. Dr. Rohwer’s research contributions fall into four major areas. Perhaps the most widely recognized of these, particularly beyond ornithology, is the role he has played in the analysis of variation in avian plumages, including status signaling, delayed plumage maturation, and color variation in raptors. His work on the behavioral correlates of variation in amount of black on the head and breast of Harris’s Sparrow (Zonotrichia querula) launched the research area usually referred to as “status signaling.” His paper on the social significance of avian winter plumage variability (Rohwer 1975), and subsequent experimental studies, catalyzed an avalanche of critical research on the significance of individual variation in plumage as well as parallel work in other animals. Together with Eivin Røskaft, Rohwer undertook the logistically challenging task of dyeing male Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) black. The surprising consequence, that blackened males often acquired better territories after their experimental treatment, spawned his “arbitrary identity badge” hypothesis, which provides a mechanism by which novel color patches may serve aggressive competition and account for the rapid color divergence in allopatry.

Dr. Rohwer’s interest in bird plumage is also reflected in his longtime interest in molt and its integration into the annual cycle (starting with his M.S. thesis at the University of Kansas). He has maintained one of the few active, question- driven research programs on avian molt. He is the unquestioned leader in the field of ecology and evolution of molt cycles, and any paper in the field cites many of his papers, or those of his students. This interest in plumage cycles inspired his often-cited papers on delayed plumage maturation. Much of Rohwer’s recent field work has targeted the documentation of what is likely a novel strategy in passerine birds, namely postbreeding migration to a resource-rich area for molting before continuing on to the wintering range.

In the late 1980s, the adoption of unrelated young by replacement mates in birds seemed especially puzzling in the face of major papers appearing on sexually selected infanticide in mammals. Rohwer solved this puzzle by showing that tolerance, and even care, of unrelated young offered future mating opportunities when dispersal was constrained (e.g., Rohwer 1986, Rohwer et al. 1999). This interest led to an elegant field experiment showing that male Yellow-headed Blackbirds recognize young they did not sire but tolerate them for their courtship value, just as egg-guarding male fishes do. As an aside, probably few ornithologists are aware of his work on human behavioral ecology (e.g., Hayward and Rohwer 2004).

Dr. Rohwer has also made outstanding contributions to the study of speciation and hybridization, starting with his heavily cited dissertation studies of meadowlarks (Sturnella spp.) and more recently with Townsend’s Warblers (Dendroica townsendi) and Hermit Warblers (D. occidentalis). In collaboration with R. M. Zink and others, he has extended this interest into several trans- Beringean and Old World groups (e.g., Zink et al. 1995), concentrating on phylogeographic patterns and species limits. This collaboration has provided the first glimpses of the evolutionary genetic history of the birds of this region. He deserves much praise for fostering multiple Russian-American collaborations and organizing a massive collecting program for birds of the for- mer Soviet Union (Rohwer et al. 2001).

Dr. Rohwer has excelled at using museum specimens to ask innovative and novel questions. He has spearheaded a major effort at the Burke Museum, and it has blossomed into a powerhouse in the world of specimen-based research. The bird collection at the Burke is probably the most rapidly growing in the world, and the wealth of data-rich traditional specimens, combined with the world’s largest spread-wing collection and one of the largest tissue (DNA) collections, makes it one of the planet’s most valuable bird collections. This all has occurred because of his leadership and vision.

For his spectacular combination of intellectual energy and empirical field- and specimen- based inquiry, the American Ornithologists’ Union is pleased to award Sievert A. Rohwer the Elliott Coues Award for 2006.