History of Research

Although the tricolored blackbird is mentioned in several articles and books dating to the mid-19th Century, the first field work focussed on tricolored blackbirds was that conducted by Johnson Neff. Johnson Neff was a biologist who worked for the Bureau of Biological Survey, the forerunner of today's U.S. Fish & Wildlife Service. Neff conducted six years of field surveys (from 1931-1936), and additional banding of nestlings until 1940, to determine the status of the birds in the Central Valley after widespread reports of the birds' disappearance from coastal locations and a sense of concern for the future of the species. Neff's work was primarily focused on the Sacramento Valley, but he also worked, in conjunction with other state and federal biologists and volunteers, at sites in the San Joaquin Valley and in southern California.

After 1940, perhaps in response to Neff's finding of fairly large numbers of remaining birds (e.g., 282,000 nests at one site in Glenn County in 1934), there followed a 20+ year period of relatively little research into tricolored blackbird status and biology.

In the 1960's, two then-graduate students from U.C. Berkeley, Gordon Orians and Robert Payne, conducted seminal research on blackbirds, including tricolors, that focused on behavior and adaptations for marsh nesting (Orians) and reproductive physiology (Payne) and helped to provide an ecological and evolutionary context for tricolor breeding, food preferences, and habitat selection and compared and contrasted tricolors with other blackbird species.

In the late 1960's, Frederick Crase, a Bureau of Reclamation biologist, and Richard DeHaven, who worked for the U.S. Fish & Wildlife Service, began working on the tricolored blackbird and studied food habits, habitat relationships, population status, and movement patterns. This work was described in a number of publications from the mid-1970's until the late 1980's (see Bibliography). This work confirmed the continuing decline in the number of tricolored blackbirds and highlighted the dependence of food supplies, especially insect abundance, on colony productivity, and suggested that otherwise apparently suitable nesting sites might be abandoned if surrounding foraging habitats were not sufficiently productive or extensive.

In the 1980's Edward C. (Ted) Beedy began field investigations of tricolors with an emphasis on both the estimation of the abundance of the species and on the factors responsible for the observed nesting failures of colonies in the Central Valley. Shortly thereafter, William J. (Bill) Hamilton III began his field investigations. Bill Hamilton's work was to continue uninterrupted for 13 field seasons, through 2005, and covered a wide range of topics, including population estimation (Beedy and Hamilton suggested using volunteers to conduct a statewide survey in a 3-day interval in April to best estimate the global population of the species), productivity estimation, foraging ecology, and the phenomenon known as "itinerant breeding", whereby individuals breed once in one location and then fly northward to a different location to breed again. Beedy and Hamilton wrote the Birds of North America treatment of the tricolored blackbird (Beedy and Hamilton 1999).