Red-shouldered hawk
The red-shouldered hawk (Buteo lineatus) is a medium-sized raptor native to eastern North America and the Pacific coast of California, distinguished by its reddish shoulder patches, barred reddish-peachy underparts, and strongly banded black-and-white tail.[1][2] Adults measure 17–24 inches (43–61 cm) in length, weigh 1.1–1.7 pounds (486–774 g), and possess a wingspan of 37–44 inches (94–111 cm), with broad, rounded wings suited for maneuvering through forested environments.[2] This species inhabits deciduous woodlands, swamp forests, and wetlands near water bodies, where it perches to hunt small mammals such as mice and voles, amphibians like frogs, reptiles including snakes, and occasionally crayfish or insects.[1][3] Known for its loud, whistled "kee-rah" call that echoes through its woodland territories, the red-shouldered hawk constructs stick nests in large tree crotches and exhibits strong site fidelity, often reusing the same nesting area annually.[2][1] Five subspecies exist, reflecting regional variations in plumage and distribution, with populations generally stable across their range and classified as Least Concern by the IUCN due to their large overall extent and adaptability to wooded suburbs.[4][1]Taxonomy
Classification and phylogeny
The red-shouldered hawk (Buteo lineatus) is classified in the order Accipitriformes, family Accipitridae, and genus Buteo, which encompasses about 28 species of New World and Old World hawks and buzzards.[5] The species was formally described by Johann Friedrich Gmelin in 1788, with the type specimen based on earlier accounts of a "barred-breasted buzzard" from eastern North America.[6] The genus name Buteo derives from Latin for "buzzard" or hawk of prey, while the specific epithet lineatus refers to the bird's lined or streaked plumage pattern.[7] Molecular phylogenetic studies using mitochondrial markers, such as cytochrome b and control region sequences, indicate a Neotropical origin for the genus Buteo, with basal divergences among South American species like B. polyosoma and B. poecilochrous, followed by radiation into North America and the Old World.[8] B. lineatus clusters within a derived New World clade of Buteo, showing close affinities to species such as the roadside hawk (B. magnirostris), though current taxonomy retains monophyly of the genus despite some evidence of paraphyly when including certain tropical forms.[9] Within the Accipitridae, Buteo forms a terminal lineage relative to Old World groups like eagles and vultures, consistent with fossil evidence of buteonine hawks appearing in the Miocene.[10] Population-level phylogeography of B. lineatus reveals deep genetic divergence between eastern and western populations, separated by Pleistocene barriers like the Mississippi River valley, with Bayesian analyses supporting distinct mitochondrial haplotypes and nuclear markers indicating limited gene flow.[11][12] Eastern lineages show further subdivision, including a differentiated South Florida clade (B. l. extimus) with fixed alleles at multiple loci, suggesting isolation during glacial cycles and potential species-level status for up to three taxa within the complex, though hybridization occurs in contact zones.[13][14] These findings challenge lumping under a single species but align with observed morphological and ecological variation across subspecies.[12]Subspecies and variation
The red-shouldered hawk (Buteo lineatus) is divided into five subspecies, differentiated by geography, body size, plumage coloration, and genetic markers, with northern populations generally larger than southern ones.[15] [13] Plumage exhibits clinal variation, with eastern subspecies showing paler underparts in southern ranges and more rufous tones northward, while the western form displays consistently darker markings.[2] [15] Genetic analyses indicate the western subspecies diverged early from eastern lineages, with the south Florida form showing distinct mitochondrial DNA haplotypes despite morphological similarities to other eastern taxa.[16] [13] The subspecies are summarized as follows:| Subspecies | Primary Range | Key Characteristics |
|---|---|---|
| B. l. lineatus (nominate) | Eastern North America, from Great Lakes to Gulf Coast | Dark-streaked rufous underparts; intermediate size; genetically clusters with southeastern forms.[17] [18] |
| B. l. alleni | Southeastern U.S., including coastal plain | Paler underparts than nominate; slightly smaller; overlaps with lineatus but shows subtle plumage gradients.[17] [13] |
| B. l. extimus | Southern Florida and West Indies (e.g., Bahamas, Cayman Islands) | Smallest size; palest plumage with reduced rufous; lower nest success rates (e.g., 0.4 fledglings per pair vs. 1.5 in northern forms); federally listed as endangered in U.S. due to habitat loss.[17] [13] [19] |
| B. l. texanus | Eastern Texas and adjacent Mexico | Intermediate between eastern and western forms in size and markings; genetically aligns with eastern group.[17] [13] |
| B. l. elegans | Western U.S., from California to Baja California | Largest subspecies; darker overall plumage with bold black-and-white wing bands; allopatric from eastern taxa, historically treated as separate species (Red-bellied hawk).[17] [15] [16] |