The triciolored blackbird is legally protected under the Migratory Bird Treaty Act, or MBTA (http://www.fws.gov/migratorybirds/intrnltr/treatlaw.html#mbta); however, the legal status of the tricolored blackbird has changed through time.
Formerly, the tricolored blackbird was exempt from the protections offered to many North American birds by the Migratory Bird Treaty Act, as most blackbirds and relatives ("yellow-headed red-winged, rusty, and Brewer's blackbirds, cowbirds, all grackles, crows, and magpies") are considered potential agricultural pests and exceptions to protection under the MBTA are possible in cases where birds are about to cause depredations "to ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance" (50 CFR 21.43). However, in 1985, the tricolored blackbird was removed from the list of exempted species and now is fully protected under the MBTA (50 CFR Part 10 13708).
Currently, the tricolored blackbird is considered a Species of Conservation Concern (http://www.fws.gov/migratorybirds/reports/BCC2002.pdf). Although this designation is not formally recognized under the Endangered Species Act, listing as a species of conservation concern acknowledges that the U.S. Fish & Wildlife Service is aware of population reductions and is a response to the 1988 amendment to the Fish and Wildlife Conservation Act mandate to the U.S. Fish and Wildlife Service (USFWS) to "identify species, subspecies, and populations of all migratory nongame birds that, without additional conservation actions, are likely to become candidates for listing under the Endangered Species Act of 1973." More information is available here (http://www.fws.gov/migratorybirds/reports/BCC2002.pdf).
Currently, the tricolored blackbird is protected under the California Fish and Game Code (Section 3503.5 and 3800) and is considered a Species of Special Concern (http://www.dfg.ca.gov/wildlife/species/ssc/docs/Table1-BSSC.pdf). Although this designation does not afford specific protections, it has been used to identify those species that are "rare, threatened, or endangered" under the California Environmental Quality Act (CEQA). More information is available here (http://www.dfg.ca.gov/wildlife/species/ssc/birds.html).
The Bureau of Land Management designates the tricolored blackbird a Sensitive Species (BLM 2003; http://www.blm.gov/nhp/efoia/nv/ib/2003/nvib2003-097a.pdf).
Not a regulatory agency, the World Conservation Union, or IUCN (http://www.iucn.org/), maintains lists of threatened and endangered species world-wide. The tricolored blackbird was placed on the IUCN Red List as Endangered in 2006 (http://redlist.org/details/150392).