Icterid

• 1. Introduction

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  Icterids are a family of birds that carry one of the stranger names in ornithology: "the jaundiced ones." That label, drawn from the Greek word íkteros, was inspired by the blazing yellow feathers many of these birds wear. But yellow is only part of the story. The Icteridae is a family of 108 species spread across 30 genera, and within that single family you find birds that eat fruit pulp, birds that crush seeds, birds that drink nectar, and birds that trick other species into raising their young. What unites a bobolink with an oropendola? What allows a single bird family to span from tiny orioles weighing 18 grams to massive oropendolas tipping the scales at 550 grams? And why did an Irish zoologist in 1825 decide these birds belonged with the starlings? Those are the threads this documentary will follow.

• 2. The Naming Tangle

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  Nicholas Vigors, the Irish zoologist who first formally grouped these birds in 1825, placed them as a subfamily he called Icterina inside the starling family Sturnidae. That assignment has since been overturned, but the name stuck. The term icterid traces back through Latin to the Greek íkteros, meaning jaundiced, a reference to the yellow coloring prominent in so many species. The naming confusion did not end with Vigors. Despite sharing similar-sounding names, icterids are only distantly related to the Old World common blackbird, which is actually a thrush. They are equally distant from the Old World orioles. To make matters more tangled, there is a separate family called the Icteriidae, created in 2017, containing just one species: the yellow-breasted chat, Icteria virens. The Icteridae and the Icteriidae are distinct families, and the similarity in their names reflects etymology, not close kinship. A 2019 phylogenetic analysis by Carl Oliveros and collaborators clarified the picture: Icteridae and Icteriidae are sister families, and together they form a clade that sits alongside the New World warbler family Parulidae.

• 3. A Family of Extremes

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  The male great-tailed grackle is 60% heavier than the female of the same species. That single statistic captures something unusual about icterids: the degree of sexual dimorphism they display by size is uniquely extreme within the passerines, the vast order of perching birds to which they belong. Males typically run larger and brighter than females. At the small end of the family sits the orchard oriole, whose females average 15 centimeters in length and 18 grams in weight. At the large end is the Amazonian oropendola, whose males reach 52 centimeters and weigh around 550 grams. That gap in body size between the smallest and largest species is greater than in any other passerine family, with one possible exception: if the kinglet calyptura belongs with the cotingas, that group would edge ahead. Beyond size, icterid species vary widely in shape, behavior, and coloration, ranging from the deeply colonial to the solitary, from seed-crushers to nectar-drinkers to brood parasites.

• 4. The Gaping Skull

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  One physical feature connects icterids across their diversity: a skull configuration that allows them to open their bills with force rather than simply close them passively. This trait, called gaping, lets birds force open gaps in bark, soil, or fruit skin to reach food hidden inside. Oropendolas and caciques use this motion specifically to split open the skins of fruit and reach the soft flesh within; their long bills are adapted to the task. Other icterids put gaping to entirely different uses. The Jamaican blackbird uses its bill to pry under tree bark and among epiphytes, filling an ecological role that is taken elsewhere in the Neotropics by woodcreepers. Cowbirds and the bobolink, meanwhile, do not gap at all; they have shorter, stubbier bills built for crushing seeds. Orioles drink nectar. The result is a family in which the same underlying jaw adaptation has been bent toward radically different food sources. Icterids also share some structural features: most have rounded tails, lack rictal bristles, and carry nine primary feathers, placing them among the nine-primaried oscines.

• 5. Where Icterids Live

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  Colombia and southern Mexico hold the highest densities of breeding icterid species anywhere in the world. The family is fundamentally a New World group, concentrated in the tropics but extending into temperate North and South America. They occupy scrub, swamp, forest, and savanna. Species like the red-winged blackbird and the long-tailed meadowlark reach into temperate zones. Temperate-dwelling icterids are migratory: many that nest in the United States and Canada move south into Mexico and Central America when seasons shift. Colonial nesting is common in the family, with some colonies reaching 100,000 birds. Oropendolas and orioles build pendulous woven nests. Some cowbird species take a different path entirely, practicing brood parasitism: females lay their eggs in the nests of other species, leaving the host bird to raise the cowbird's chick, a strategy that parallels the behavior of some Old World cuckoos.

• 6. Pests, Threats, and Folklore

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  Red-winged blackbirds in the United States are classified as the worst vertebrate pests on certain crops, particularly rice. The cost of controlling blackbirds in California was recorded at $30 per acre in 1994. Not all icterids have fared so well against human-altered landscapes. The Jamaican blackbird, the yellow-shouldered blackbird, and the St. Lucia oriole are all threatened by habitat loss. The tricolored blackbird of California faces both habitat loss and direct destruction of its nests. In Peru, cacique and oropendola species carry the name paucar or similar terms. Native Americans there have long considered paucares exceptionally intelligent and feed the birds' brains to children in the belief it will make them fast learners. Because the male paucar takes no role in nesting or raising young, the same name is applied as a social label to a man who avoids work. Two prehistoric icterid genera are also known from fossil remains: Pandanaris, recovered from Rancho La Brea, and Pyelorhamphus, found at Shelter Cave.