Tricolored blackbirds are preyed on by a variety of species. Predators include mammals such as gray foxes (Urocyon cinereoargentus) and skunks (Mephitis mephitis). Larger birds, such as common ravens (Corvus corax), black-crowned night herons (Nycticorax nycticorax), northern harriers (Circus cyaneus) and Cooper’s hawks (Accipiter cooperii) also prey on tricolored blackbirds. In more urban areas, feral cats (Felis catus) prey on nests. Tricolored blackbirds do not fight back against predators and tend to be less aggressive than red-winged blackbirds.
Known Predators:
Tricolored blackbirds exhibit sexual dimorphism. Males are larger than females and possess dark red shoulder patches with white median coverts on the wings, giving the species its name. Males have brown plumage in the fall. Females are shades of gray with a lighter gray throat. One way to distinguish them from female red-winged blackbirds is that they tend to be darker, have more pointed wingtips, and have more slender bills. They are about 22 cm long with a 35.5 cm wingspan. They weigh approximately 59.5 grams.
Average mass: 59.5 g.
Average length: 22.2 cm.
Average wingspan: 35.5 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; male more colorful
Not much is known about the lifespan of tricolored blackbirds due to few banded recoveries. They can live up to 13 years. Predation and harsh weather conditions account for the majority of mortality. Further studies on survivorship need to be conducted.
Range lifespan
Status: wild: 13 (high) years.
Tricolored blackbirds are found in areas near water, such as marshes, grasslands, and wetlands. They require some sort of substrate nearby to build nests. This substrate is often in the form of aquatic vegetation. They also need foraging areas, which can consist of grassland or agricultural pastures such as rice, grain, or alfalfa.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: savanna or grassland
Wetlands: marsh
Other Habitat Features: agricultural
Tricolored blackbirds (Agelaius tricolor) are found in western coastal North America. They are native to California and parts of Oregon, Washington, and Nevada. Highest concentrations are found in the Central and San Joaquin Valleys of California, as well as coastal areas.
Biogeographic Regions: nearctic (Native )
Tricolored blackbirds have a nasal “oo-grreee” call that begins loud and gradually gets softer. They also emit a “drdodrp” call. Their calls have a lower pitch than those of red-winged blackbirds (Agelaius phoeniceus). Females tend to be silent during incubation.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Tricolored blackbirds are federally protected under the Migratory Bird Treaty Act of 1918. They are listed as endangered bu the International Union for Conservation of Nature and Natural Resources (IUCN) Red List. The California Department of Fish and Game lists tricolored blackbirds as Species of Special Concern. Population declines are due to loss of wetland habitat, urban sprawl, and agricultural needs. This has resulted in greatly reduced foraging and breeding areas. Several conservation efforts are underway to preserve this species. Tricolored blackbird habitat development on public land and colony preservation can help stimulate populations. Education and outreach is important for educating landowners on proper ways to coexist with the tricolored blackbirds. Continued tracking is helping researchers understand breeding and migrating behaviors of this species so that more precise conservation plans can be made.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
Tricolored blackbirds are also considered agricultural pests because they often forage in nearby croplands. They can feed on young rice grains, oats, and barley.
Negative Impacts: crop pest
Tricolored blackbirds help manage insect populations that harm crops. They are especially significant during insect outbreak years where insects such as grasshoppers are in high abundance. By feeding on agriculturally harmful insects, higher crop yields can be obtained.
Positive Impacts: controls pest population
Many tricolored blackbirds are dependent on rice-growing fields and duck-hunting areas of central California. Their populations change in response to insect abundances. They are ecologically dependent on insect outbreaks for food. Thus, they help to keep rampant insect populations under control.
Tricolored blackbirds are omnivorous, feeding on both animal and plant matter. Their diet depends on the region they live in and what crops or insects are most abundant. Insect prey includes grasshoppers, beetles, moths, and fly larvae. Their diet also includes grains, seeds, rice, and other crops. Nestlings are fed primarily insects.
Animal Foods: insects
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: omnivore
Males attract females by singing and displaying courtship behaviors. The species exhibits polygyny, one male may breed with 1 to 4 females.
Mating System: polygynous
Tricolored blackbirds breed in both the spring and fall. Tricolored blackbirds exhibit itinerant breeding, meaning that they breed twice a year in two separate locations. Spring breeding takes place in mid-March through late April. Breeding colonies consisting of up to 200,000 nests. Clutch sizes in both breeding seasons ranged between one and four. The most common clutch size is three. Incubation lasts between 11 and 14 days. Females build nests and lay their eggs in approximately one week. Females also take part in incubating the young. Fledging occurs approximately 9 days after the chicks are born. An additional 15 days or so are required for the young to live away from their parents. Males begin to breed when they are two years of age. Females are able to breed when they are one year of age.
Breeding interval: Breeding intervals are not reported.
Breeding season: Breeding can occur in spring and in fall.
Range eggs per season: 1 to 4.
Average eggs per season: 3.
Range time to hatching: 11 to 14 days.
Average fledging age: 9 days.
Average time to independence: 14 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Males and females care for the young. Females remain at nests during the daytime to incubate the eggs. Males care for the young after they hatch. They range up to 6.5 km to acquire food for nestlings.
Parental Investment: altricial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Protecting: Male, Female)
The tricolored blackbird (Agelaius tricolor) is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific coast of North America, from Northern California in the U.S. (with occasional strays into Oregon), to upper Baja California in Mexico.
This highly social and gregarious bird forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds.
The common name is taken from the male bird's distinctive white stripes underneath their red shoulder patches, or "epaulets", which are visible when the bird is flying or displaying.
Despite the similar names, this bird is not related to the Old World common blackbird, which is a thrush (Turdidae).
The species' call sounds slightly more nasal than that of the red-wing's - a nasal kip and a sharp check. The male's song is a garbled on-ke-kaaangh. The bird migrates south during the colder seasons to Mexico and back to northern California during the warmer seasons.
The tricolored blackbird does not have any officially recognized subspecies, although there is a population in southern California that may require genetic evaluation.[2]
The tricolored blackbird nests in colonies, but scholars disagree on whether the costs outweigh the benefits of these breeding habits.[3] Nonetheless, nesting in colonies makes the tricolor susceptible to environmental changes. Although the tricolor has been able to adapt to some of the landscape changes, habitat loss played a major role in the reduction of its population.[4]
The tricolor originally could be found in the marshes of California, nesting in wetland cattails and bulrushes. Scholars have noted a reduction in freshwater marshes as breeding grounds for the tricolored blackbird.[5][6][7][4] Largely, this is due to human activity, and it’s estimated that between the 1930s and 1980s alone, over 95% of wetlands were disappeared.[8] Also in this period, the observed tricolor population saw an 89% reduction, while the average colony size saw a 63% reduction.[6][9] Altogether, the tricolor population dropped from several million to only a few hundred thousand during the twentieth century.[10] Nevertheless, the tricolor was able to adapt in response to these severe landscape reductions. It began to use both native and non-native vegetation as well as agricultural fields as their breeding and foraging grounds.[4]
In the 1930s, over 93% of the tricolor’s colonies were nested in freshwater marshes,[11] but by the early twenty-first century, only 35% of colonies could be found in wetlands.[12] In 2008, over a fourth of colonies were using non-native vegetation to nest, most notably Himalayan blackberry brambles. Although population decline was a consequence of agricultural intensification over the twentieth century, the birds were able to use these environmental changes to their advantage. The 2008 tricolored blackbird census found that nearly half of the total population nested in colonies inside of the grain fields of dairy farms.[4][12]
As the twentieth century progressed, the tricolor began to increase in concentration within certain colonies. Specifically, in 2000, 59% birds were housed in one of California’s ten largest colonies, and this number increased to 81% by 2011. Mega-colonies of the tricolor have begun to form in the San Joaquin Valley’s numerous agricultural fields.[12][4] Although the tricolor population consistently decreased during the twentieth century and into the twenty-first century, the population nested in San Joaquin Valley grew exponentially during this time. The number of tricolors in California’s San Joaquin Valley in 1994 was 230% of what it was in 1937.[13][11] By 2008, over 86% of California’s population were located here.[12]
Conservation efforts by the National Audubon Society in collaboration with the U.S. Fish and Wildlife Service have seen an impact on population numbers. The California population of tricolors saw an increase in the 2017 state survey from previous years. Nonetheless, most of this population gain was within the San Joaquin Valley or in San Benito County. Other regions of California saw a reduction in population in the 2017 census, including Sacramento Valley, with observations down by about 33% from the prior census in 2014. There has been a steady decline of the tricolors observed in this region over the twentieth and twenty-first centuries, with a greater proportion of birds moving to the San Joaquin Valley.[4][12] There has also been an overall population decline in Southern California as well, following the dairy industry’s move out of Southern California in the 1980s, in favor of the San Joaquin Valley.[14] The other California region that saw a population increase in 2017 was the Central Coast. Historically, the Central Coast and Central Valley housed millions of tricolors before the population decline associated with human agricultural activity.[11][4] Still, the population increase seen in 2017—from 627 to 17,576 birds—likely was not due to a growing number of tricolors coming to the Central Coast. Instead, this drastic population increase likely was a result of better survey efforts. Three large new colonies were observed in 2017, two of which were in previously unknown or un-surveyed locations. Expanded knowledge of the tricolor’s breeding habits led researchers to increase their survey efforts in locations they suspected housed bird colonies.[4]
Although most regions of California either remained constant or saw a decrease in the tricolor population in 2017, there was an increase in the state overall. The 2017 census, however, did prove that human conservation efforts can be successful. In Southern California, the population remained relatively constant from 2014 to 2017, but the distribution in this region changed. Riverside County saw a significant increase in population, and 57% of the tricolors observed in Southern California were in one single colony. The San Jacinto Wildlife Area in Riverside County had been the site of successful conservation efforts to provide the tricolor with nesting and foraging habitats.[4]
In 1990 the Department of Fish and Game (DFG) of California, based on significant decline in population numbers documented in the 1980s, added the tricolored blackbird to the published list of "Bird Species of Special Concern". This classification is an "administrative designation intended to alert biologists, land managers and others to a species declining status and encourages them to provide additional management considerations". At this time the tricolored was added to the U.S. Fish and Wildlife Service (USFWS) list of Birds of Conservation Concern.
By 1991, the tricolor blackbird's breeding population had fallen to approximately thirty-five thousand adults. This prompted a petition submitted by the Yolo chapter of the National Audubon Society to the California Fish and Game Commission. The petition brought the tricolored blackbird under consideration for endangered classification. The classification was granted until the breeding season in 1992. It was then that researchers discovered a population exceeding three hundred thousand adults. A petition to withdraw the endangered classification was submitted and accepted. Conservation measures were supposed to be developed and implemented to avoid a future decline as seen before. These measures were developed, but only very limited progress was made in preventing the future decline of the tricolored blackbird. Interested groups started reconvening shortly after the year 2000. Managing groups found startling results when conducting population research.[15]
In 2006 the tricolored blackbird was classified as Endangered by BirdLife International. Like the extinct passenger pigeon, the colonial nature of the tricolored blackbird makes it particularly vulnerable to extinction. Native grasslands once used for nesting and feeding have been lost to urban and agricultural development. Birds adapted to nesting in agricultural fields have been disturbed by harvesting during the breeding season. Once the tricolored blackbird was placed on the BirdLife Endangered Species list, it officially became a concern both regionally and nationally.
The U.S. Fish and Wildlife Service maintained the following "Primary conservation priorities for Tricolor habitat conservation and management" (The Tricolored Blackbird Working Group, 2007):
In 2018, the tricolored blackbird was listed as a threatened species under the California Endangered Species Act, years after petitioning by the Center for Biological Diversity.[16]
The tricolored blackbird (Agelaius tricolor) is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific coast of North America, from Northern California in the U.S. (with occasional strays into Oregon), to upper Baja California in Mexico.
This highly social and gregarious bird forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds.
The common name is taken from the male bird's distinctive white stripes underneath their red shoulder patches, or "epaulets", which are visible when the bird is flying or displaying.
Despite the similar names, this bird is not related to the Old World common blackbird, which is a thrush (Turdidae).
The species' call sounds slightly more nasal than that of the red-wing's - a nasal kip and a sharp check. The male's song is a garbled on-ke-kaaangh. The bird migrates south during the colder seasons to Mexico and back to northern California during the warmer seasons.
