Tricoloured blackbird  (Agelaius tricolor)

Historically, the tricoloured blackbird’s population underwent a serious decline, primarily due to habitat loss as a result of urbanisation, conversion of land for agriculture and the draining of wetlands. In addition, hunting of this species for sale at markets and deliberate poisoning to safeguard crops, were both extensively practiced up until their ban in 1970s and 1980s (4). Despite losing a great deal of its native habitat, the tricoloured blackbird has adapted, and today large numbers breed in silage and in upland regions (3). Unfortunately, in these environments this species faces new threats, as many colonies are being decimated by herbicide poisoning, predation and, in particular, silage harvesting. The silage harvest takes place while the tricoloured blackbird is laying eggs and brooding chicks, and may therefore destroy an entire colony’s breeding efforts. With some silage colonies comprising tens of thousands of birds, these losses represent a significant portion of this species’ global population (3) (4).

Efforts to conserve the tricoloured blackbird have been made by the US Fish and Wildlife Service by either purchasing whole areas of silage from private landowners, or by paying them to delay the silage harvest long enough to allow the tricoloured blackbird to successfully breed (4). While this has been extremely beneficial for the survival of tricoloured blackbird colonies, the US Fish and Wildlife Service do not consider it to be a long-term solution for the management of this species. Other proposed measures to conserve this species, include delaying herbicide application until the tricoloured blackbird has completed its breeding cycle, and the creation of areas of marshland and blackberries within key silage nesting regions, offering a safe, alternative breeding habitat (2).

The tricoloured blackbird is listed in California as a Species of Special Concern and a Migratory Bird of Management Concern, categories which help to highlight this species’ decline, but do not provide the same levels of legal protection as being listed as Endangered under the Endangered Species Act (2). Hence in 2004, the non-governmental conservation organisation, The Center for Biological Diversity, petitioned the US Fish and Wildlife Service to list the tricoloured blackbird as Endangered, but was, unfortunately, unsuccessful (7). Nevertheless, in 2007, the Tricolored Blackbird Working Group, a collaboration of various conservation organisations, produced a comprehensive conservation plan for this species. With adequate funding, the actions proposed by the plan should help to ensure the survival of this fascinating species (6).