Tricolored blackbird | |
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A male tricolored blackbird in California, United States | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Passeriformes |
Family: | Icteridae |
Genus: | Agelaius |
Species: | A. tricolor |
Binomial name | |
Agelaius tricolor (Audubon, 1837) | |
range of Tricolored blackbird |
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 red-winged blackbird is a passerine bird of the family Icteridae found in most of North America and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and northwestern Costa Rica. It may winter as far north as Pennsylvania and British Columbia, but northern populations are generally migratory, moving south to Mexico and the Southern United States. Claims have been made that it is the most abundant living land bird in North America, as bird-counting censuses of wintering red-winged blackbirds sometimes show that loose flocks can number in excess of a million birds per flock and the full number of breeding pairs across North and Central America may exceed 250 million in peak years. It also ranks among the best-studied wild bird species in the world. The red-winged blackbird is sexually dimorphic; the male is all black with a red shoulder and yellow wing bar, while the female is a nondescript dark brown. Seeds and insects make up the bulk of the red-winged blackbird's diet.
The American white ibis is a species of bird in the ibis family, Threskiornithidae. It is found from Virginia via the Gulf Coast of the United States south through most of the coastal New World tropics. This particular ibis is a medium-sized bird with an overall white plumage, bright red-orange down-curved bill and long legs, and black wing tips that are usually only visible in flight. Males are larger and have longer bills than females. The breeding range runs along the Gulf and Atlantic Coast, and the coasts of Mexico and Central America. Outside the breeding period, the range extends further inland in North America and also includes the Caribbean. It is also found along the northwestern South American coastline in Colombia and Venezuela. Populations in central Venezuela overlap and interbreed with the scarlet ibis. The two have been classified by some authorities as a single species.
The California condor is a New World vulture and the largest North American land bird. It became extinct in the wild in 1987 when all remaining wild individuals were captured, but has since been reintroduced to northern Arizona and southern Utah, the coastal mountains of California, and northern Baja California in Mexico. It is the only surviving member of the genus Gymnogyps, although four extinct members of the genus are also known. The species is listed by the International Union for the Conservation of Nature as Critically Endangered, and similarly considered Critically Imperiled by NatureServe.
The yellow-headed blackbird is a medium-sized blackbird with a yellow head.
The hooded oriole is a medium-sized New World oriole. The male of this species ranges in color from a bright orange to a paler yellow, with a black back, face, tail and bib, with the wing containing two white bars. The female is more of an olive color with some yellow accents.
The black-capped petrel, also known as the diablotín, is a small seabird native to the West Indies in the genus Pterodroma. It is a long-winged petrel with a grey-brown back and wings, with a white nape and rump. Underparts are mainly white apart from a black cap and some dark underwing markings. It picks food items such as squid from the ocean surface.
Brewer's blackbird is a medium-sized New World blackbird. It is named after the ornithologist Thomas Mayo Brewer.
Forster's tern is a tern in the family Laridae. The genus name Sterna is derived from Old English "stearn", "tern", and forsteri commemorates the naturalist Johann Reinhold Forster.
The lark sparrow is a fairly large New World sparrow. It is the only member of the genus Chondestes.
The spotted owl is a species of true owl. It is a resident species of old-growth forests in western North America, where it nests in tree hollows, old bird of prey nests, or rock crevices. Nests can be between 12 and 60 metres high and usually contain two eggs. It is a nocturnal owl which feeds on small mammals and birds. Three subspecies are recognized, ranging in distribution from British Columbia to Mexico. The spotted owl is under pressure from habitat destruction throughout its range, and is currently classified as a near-threatened species.
The marbled murrelet is a small seabird from the North Pacific. It is a member of the family Alcidae, which includes auklets, guillemots, murres and puffins. It nests in old-growth forests or on the ground at higher latitudes where trees cannot grow. The marbled murrelet has declined in number since humans began logging its nest trees in the latter half of the 19th century. The decline of the marbled murrelet and its association with old-growth forests, at least in the southern part of its range, have made it a flagship species in the forest preservation movement.
Bell's vireo is a songbird that migrates between a breeding range in Western North America and a winter range in Central America. It is dull olive-gray above and whitish below. It has a faint white eye ring and faint wing bars.
The mountain plover is a medium-sized ground bird in the plover family (Charadriidae). It is misnamed, as it lives on level land. Unlike most plovers, it is usually not found near bodies of water or even on wet soil; it prefers dry habitat with short grass and bare ground. Its height is in the range of 5-9 inches, and length in the range of 8-10 inches ; and it weighs around 102 grams.
The Galápagos petrel is one of the six endemic seabirds of the Galápagos. Its scientific name derives from Ancient Greek: Pterodroma originates from pteron and dromos, meaning "wing" and "runner", and phaeopygia comes from phaios and pugios, meaning "dusky" and "rump". Members of Pterodroma genus are also called the gadfly petrels because their erratic twisting and turning in flight resemble that of gadflies.
The least tern is a species of tern that breeds in North America and locally in northern South America. It is closely related to, and was formerly often considered conspecific with, the little tern of the Old World. Other close relatives include the yellow-billed tern and Peruvian tern, both from South America.
The yellow-shouldered blackbird, known in Puerto Rican Spanish as mariquita de Puerto Rico or capitán, is a species of blackbird endemic to Puerto Rico. It has black plumage with a prominent yellow patch on the wing. Adult males and females are of similar appearance. The species is predominantly insectivorous.
The San Luis National Wildlife Refuge Complex is located in the northern San Joaquin Valley, within Merced County and Stanislaus County of California. The complex, with four federal National Wildlife Refuges, is managed by the U.S Fish & Wildlife Service.
The Bitter Creek National Wildlife Refuge is located in the foothills of the southwestern San Joaquin Valley in Kern County, California. The refuge is one of four units of the Hopper Mountain National Wildlife Refuge Complex for California condors.
The San Joaquin River National Wildlife Refuge is a protected area of along the San Joaquin River in the northern San Joaquin Valley, California. It is within San Joaquin County and Stanislaus County.
Canebrake Ecological Reserve is a 6,700-acre (27 km2) nature reserve in the South Fork Valley of Kern County, 20 miles (32 km) east of Lake Isabella, California. It is located in the Southern Sierra Nevada region.