Birds from Coahuila, Mexico Informative Summary

Overview:

This detailed report, published in 1959, provides a comprehensive overview of the avian diversity found in Coahuila, Mexico. The state’s diverse topography and climate result in a unique blend of species, encompassing those associated with eastern North America, western North America, and those endemic to Mexico. The text highlights the influence of geography and climate on bird distribution, including the isolation of certain populations in the arid western regions and the presence of boreal species in the higher mountain ranges.

The author explores the historical origins of the avifauna, suggesting that the cooling climate during the late Pliocene and Pleistocene periods led to the southward migration of many North American birds, some of which ultimately settled in Coahuila. The arid conditions that followed drove many tropical species out, leaving a fauna adapted to the harsh desert environment. The paper also considers the origins of bird families, revealing a significant influence from the Old World, South America, and North America, mirroring similar analyses conducted in other regions.

Key findings:

Geographic Isolation and Speciation: The arid western regions of Coahuila act as barriers to movement for some bird species, leading to isolation of certain populations and unique ecological adaptations.
Diversity of Bird Origins: The breeding avifauna of Coahuila reflects a complex historical tapestry, with significant contributions from both North and South America, as well as the Old World.
Adaptations to Aridity: The presence of species well-suited to desert environments underscores the influence of the state’s arid climate on bird diversity.

Learning:

Bird Distribution and Ecology: The text provides a fascinating illustration of how topography, climate, and historical events shape bird distribution and ecological adaptations.
Biotic Provinces: You’ll learn about the concept of biotic provinces, which are regions characterized by distinct ecological communities, and how these influence bird diversity.
Subspecies Variation: The paper demonstrates how geographic isolation can lead to subspecific variation within bird species, resulting in distinct populations with unique physical and behavioral traits.

Historical Context:

The publication was written in 1959, a period of significant scientific inquiry into bird distribution and ecology. This context is evident in the meticulous documentation of specimen measurements and the discussion of taxonomic debates surrounding various species. The report reflects the evolving understanding of bird populations and the impact of environmental factors.

Facts:

Coahuila’s Diverse Habitats: The state’s landscape includes mountains, deserts, and a coastal plain, creating a variety of habitats that support a wide range of bird species.
Aridity’s Influence: Western Coahuila’s aridity restricts the diversity of breeding populations compared to the more humid eastern regions.
Boreal Species in High Mountains: Boreal forests in southeastern Coahuila provide habitat for certain northern bird species, such as Goshawks and Pine Siskins.
Disjunct Distribution: Some bird species associated with western North America are found only in southeastern Coahuila, likely due to past climate shifts and the formation of deserts.
Local Adaptation: The isolation of populations in the Sierra del Carmen has led to local adaptations, such as the expansion of the Ladder-backed Woodpecker’s ecological niche.
Migration Patterns: Both eastern and western flyway migrants pass through Coahuila, contributing to the state’s avian diversity.
Southern Influence: Birds from central and southern Mexico have reached southeastern and southwestern Coahuila.
Historical Climate Change: The cooling climate during the late Pliocene and Pleistocene periods drove many birds southward, contributing to the present avifauna of Coahuila.
Family Origins: The families of birds breeding in Coahuila have roots in the Old World, South America, and North America, demonstrating the global origins of the state’s avian heritage.
Black Vulture Distribution: While common in eastern Coahuila, the Black Vulture is uncommon in the western part of the state, potentially due to the lack of suitable carrion sources in the desert.
Sharp-shinned Hawk Subspecies: Two subspecies of the Sharp-shinned Hawk, velox and suttoni, occur in Coahuila, with suttoni being more prominent in the southeastern region.
Turkey Population: The Turkey in Coahuila is restricted to the northern section of the state, likely due to the limited availability of suitable habitat in the arid south.
Swainson’s Hawk Breeding: The presence of a Swainson’s Hawk with enlarged testes in June indicates that this species breeds in Coahuila.
Gray Hawk Occurrence: The Gray Hawk, while not recorded frequently, is likely present in Coahuila based on its distribution in neighboring states.
Harris’ Hawk Prevalence: Harris’ Hawk is particularly common in southern Coahuila, where it benefits from the abundance of prey in the desert.
Prairie Falcon Wintering: The Prairie Falcon, a winter visitant, is uncommon in Coahuila, with its presence likely tied to the availability of prey during the colder months.
Pigeon Hawk Occurrence: The Pigeon Hawk is uncommon in Coahuila, with its presence likely related to migration patterns and the availability of suitable hunting grounds.
Sparrow Hawk Breeding: The presence of a Sparrow Hawk with enlarged testes in April suggests that this species breeds in Coahuila.
Bobwhite Distribution: The Bobwhite’s range extends further west in Coahuila than previously documented, potentially due to the availability of suitable habitat.
Scaled Quail Subspecies: Three subspecies of the Scaled Quail, pallida, castanogastris, and squamata, occur in Coahuila, with pallida dominating the northwestern region, castanogastris being found in the northeastern section, and squamata in the southern region.
Harlequin Quail Subspecies: Two subspecies of the Harlequin Quail, mearnsi and montezumae, are present in Coahuila, with mearnsi being found in the northwestern region and montezumae in the southeastern part of the state.
Thick-billed Parrot Breeding: The presence of Thick-billed Parrots in a spruce-fir-pine-aspen association in southeastern Coahuila indicates breeding in the region.
Yellow-billed Cuckoo Breeding: The presence of Yellow-billed Cuckoos with enlarged testes in June suggests breeding in northeastern Coahuila.
Roadrunner Breeding: The presence of a female Roadrunner with a large ovum in June indicates that this species breeds in Coahuila.

Statistics:

Bird Species Count: At least 312 named kinds of 249 species of birds have been recorded in Coahuila, with an estimated 100 more species yet to be documented.
Breeding Species: At least 154 of the species listed in the paper probably breed in Coahuila.
Percentage of Breeding Birds: 43% of the breeding birds in Coahuila are associated with western North America, 6% with eastern North America, 30% with both, 20% with Mexico and the southwestern United States, and 1% are endemic to Mexico.
Family Origins: The breeding bird families of Coahuila can be traced back to: Old World (24.7%), South America (24%), North America (37%), and an unanalyzed group (14.3%).
Turkey Weight: Female Turkeys in Coahuila can weigh up to 9 pounds, while males can reach 11.5 pounds.
Harlequin Quail Breeding: A male Harlequin Quail collected in the Sierra del Carmen on September 7 was in breeding condition.
Flammulated Owl Abundance: Seven Flammulated Owls were collected in the pines and oaks at 7000 feet in Carboneras Canyon, indicating a significant population in the region.
Acorn Woodpecker Abundance: The Acorn Woodpecker is abundant in the oak and pine-oak belts of Coahuila, ranging from 4950 to 8000 feet in elevation.
Red-shafted Flicker Distribution: The Red-shafted Flicker, subspecies C. c. nanus, is common throughout Coahuila, with a few individuals showing signs of intergradation with C. c. collaris.
Golden-fronted Woodpecker Intergradation: Golden-fronted Woodpeckers in Coahuila exhibit varying degrees of intergradation between the subspecies aurifrons and incanescens.
Violet-green Swallow Intergradation: The two subspecies of the Violet-green Swallow, thalassina and lepida, intergrade in Coahuila, with those from the north being closer to lepida and those from the south closer to thalassina.
Black-eared Bushtit Intergradation: The Black-eared Bushtit subspecies, lloydi and iulus, also show signs of intergradation in Coahuila.
Mexican Jay Abundance: The Mexican Jay is the most abundant bird species in the Sierra del Carmen.
White-necked Raven Breeding: The presence of White-necked Ravens with enlarged testes in May and June indicates that this species breeds in Coahuila.
Black-crested Titmouse Subspecies: Two subspecies of the Black-crested Titmouse, dysleptus and atricristatus, are present in Coahuila, with dysleptus found in the northwestern region and atricristatus in the southeastern part.
Verdin Population: The Verdin, found up to about 5000 feet in Coahuila, has been recorded breeding in the state.
Black-eared Bushtit Breeding: A male Black-eared Bushtit with enlarged testes in March suggests breeding in the region.
White-breasted Nuthatch Subspecies: Two subspecies of the White-breasted Nuthatch, nelsoni and mexicana, occur in Coahuila, with nelsoni being found in the northern region and mexicana in the south.
Pigmy Nuthatch Breeding: The Pigmy Nuthatch has been observed breeding in the Sierra del Carmen.
Brown Creeper Subspecies: Three subspecies of the Brown Creeper, americana, montana, and albescens, are recorded in Coahuila, with albescens being more prevalent in the southeastern part of the state.
Brown-throated Wren Subspecies: Two subspecies of the Brown-throated Wren, cahooni and compositus, are present in Coahuila, with cahooni being found in the northern region and compositus in the southeastern part.
Cactus Wren Subspecies: Two subspecies of the Cactus Wren, couesi and guttatus, are present in Coahuila, with couesi being more prevalent in the northwestern region and guttatus in the southeastern part.
Cañon Wren Breeding: The Cañon Wren has been observed breeding in the Sierra del Carmen.
Rock Wren Breeding: The Rock Wren has been observed breeding in the state.
Mockingbird Breeding: The Mockingbird is sparsely distributed throughout Coahuila, but evidence suggests that this species breeds in the state.
Long-billed Thrasher Breeding: The Long-billed Thrasher, subspecies T. l. sennetti, is uncommon in Coahuila, but breeding has been observed in the northeastern part of the state.
Curve-billed Thrasher Subspecies: Two subspecies of the Curve-billed Thrasher, celsum and oberholseri, are present in Coahuila, with celsum being found in the northwestern region and oberholseri in the eastern and southern portions.
Crissal Thrasher Subspecies: Two subspecies of the Crissal Thrasher, dorsale and dumosum, are present in Coahuila, with dorsale being found in the northern region and dumosum in the southeastern part.
Aztec Thrush Occurrence: The Aztec Thrush is rare in Coahuila, with its presence representing a significant range extension.
Hermit Thrush Subspecies: Three subspecies of the Hermit Thrush, guttata, sequoiensis, and auduboni, have been recorded in Coahuila.
Western Bluebird Breeding: The Western Bluebird, subspecies S. m. mexicana, breeds in the southern mountains of Coahuila.
Black-capped Vireo Breeding: The Black-capped Vireo has been observed breeding in central Coahuila.
White-eyed Vireo Subspecies: Two subspecies of the White-eyed Vireo, noveboracensis and micrus, are present in Coahuila, with micrus being a breeding resident in the state.
Hutton’s Vireo Subspecies: Two subspecies of Hutton’s Vireo, stephensi and carolinae, occur in Coahuila, with carolinae being a breeding resident in the state.
Bell’s Vireo Breeding: Bell’s Vireo has been observed breeding in Coahuila.
Yellow-throated Vireo Breeding: The Yellow-throated Vireo has been observed breeding in Coahuila, potentially representing a southward range expansion.
Solitary Vireo Subspecies: Two subspecies of the Solitary Vireo, solitarius and cassinii, are present in Coahuila.
Red-eyed Vireo Breeding: The Red-eyed Vireo, while uncommon in Coahuila, has been observed breeding in the northeastern part of the state.
Painted Redstart Breeding: The Painted Redstart, subspecies S. p. picta, has been observed breeding in both the Sierra del Carmen and the Sierra Guadalupe.
Brown-headed Cowbird Subspecies: Three subspecies of the Brown-headed Cowbird, ater, artemisiae, and obscurus, are present in Coahuila.
Western Tanager Migration: The Western Tanager is a common migrant in Coahuila, but it does not breed in the state.
Hepatic Tanager Subspecies: Two subspecies of the Hepatic Tanager, dextra and hepatica, are present in Coahuila, with hepatica being more prevalent in the highlands west of the Sierra Madre Oriental.
Summer Tanager Subspecies: Two subspecies of the Summer Tanager, rubra and cooperi, occur in Coahuila, with rubra found in the northeastern region and cooperi in the other regions of the state.
Cardinal Breeding: The Cardinal, subspecies R. c. canicaudus, is common in Coahuila, with breeding observed in the northeastern part of the state.
Pyrrhuloxia Breeding: The Pyrrhuloxia, subspecies P. s. sinuata, is common in Coahuila, with breeding observed in the state.
Black-headed Grosbeak Breeding: The Black-headed Grosbeak, subspecies P. m. melanocephalus, has been observed breeding in Coahuila.
Blue Grosbeak Subspecies: Three subspecies of the Blue Grosbeak, interfusa, caerulea, and eurhyncha, are present in Coahuila.
Indigo Bunting Breeding: The Indigo Bunting, a rare occurrence in Coahuila, has been observed in breeding behavior.
Varied Bunting Breeding: The Varied Bunting, subspecies P. v. versicolor, has been observed breeding in northwestern Coahuila.
Painted Bunting Breeding: The Painted Bunting, subspecies P. c. pallidior, is a common breeding resident in Coahuila.
House Finch Breeding: The House Finch, subspecies C. m. potosinus, is common in Coahuila, with breeding observed in the state.
American Goldfinch Occurrence: The American Goldfinch, subspecies S. t. pallidus, is an uncommon migrant or winter visitant to Coahuila.
Lesser Goldfinch Breeding: The Lesser Goldfinch, subspecies S. p. psaltria, is common in Coahuila, with breeding observed in the state.
Rufous-capped Atlapetes Breeding: The Rufous-capped Atlapetes, subspecies A. p. dilutus, is uncommon in southeastern Coahuila, with breeding observed in the state.
Olive Sparrow Breeding: The Olive Sparrow, subspecies A. r. rufivirgata, is uncommon in Coahuila, with breeding observed in the state.
Green-tailed Towhee Migration: The Green-tailed Towhee is a common migrant and winter visitant in Coahuila.
Rufous-sided Towhee Subspecies: Two subspecies of the Rufous-sided Towhee, gaigei and orientalis, are present in Coahuila.
Brown Towhee Subspecies: Two subspecies of the Brown Towhee, potosinus and texanus, are present in Coahuila.
Lark Bunting Wintering: The Lark Bunting is an uncommon winter visitant to Coahuila.
Savannah Sparrow Subspecies: Several subspecies of the Savannah Sparrow, oblitus, brooksi, anthinus, and nevadensis, are present in Coahuila.
Grasshopper Sparrow Migration: The Grasshopper Sparrow, subspecies A. s. perpallidus, is an uncommon spring and possibly fall migrant in Coahuila.
Vesper Sparrow Wintering: The Vesper Sparrow, subspecies P. g. confinis, is an uncommon winter visitant to Coahuila.
Lark Sparrow Breeding: The Lark Sparrow, subspecies C. g. strigatus, is uncommon in Coahuila, with breeding observed in the state.
Rufous-crowned Sparrow Subspecies: Two subspecies of the Rufous-crowned Sparrow, tenuirostris and boucardi, are present in Coahuila.
Cassin’s Sparrow Breeding: Cassin’s Sparrow is common in Coahuila, with breeding observed in the state.
Black-throated Sparrow Subspecies: Three subspecies of the Black-throated Sparrow, bilineata, opuntia, and grisea, are present in Coahuila.
Mexican Junco Breeding: The Mexican Junco, subspecies J. p. palliatus, is common in Coahuila, with breeding observed in the state.
Chipping Sparrow Migration: The Chipping Sparrow, subspecies S. p. arizonae, is a common spring and possibly fall migrant in Coahuila.
Clay-colored Sparrow Migration: The Clay-colored Sparrow is a migrant or winter visitant to Coahuila.
Brewer’s Sparrow Wintering: Brewer’s Sparrow, subspecies S. b. breweri, is likely a winter resident in much of Coahuila.
Field Sparrow Migration: The Field Sparrow, subspecies S. p. arenacea, is an uncommon spring and probably fall migrant in Coahuila.
White-crowned Sparrow Migration: The White-crowned Sparrow, subspecies Z. l. leucophrys, is a fairly common migrant or winter visitant to Coahuila.
Lincoln’s Sparrow Migration: Lincoln’s Sparrow, subspecies M. l. lincolnii, is a fairly common migrant or winter visitant to Coahuila.
Swamp Sparrow Migration: The Swamp Sparrow, subspecies M. g. ericrypta, is a migrant or winter visitant to Coahuila.

Terms:

Biotic Province: A region with a distinct set of ecological communities, characterized by specific climate, topography, and vegetation.
Disjunct Distribution: A pattern of species distribution where populations are separated by significant distances.
Cline: A gradual change in a trait over a geographic range.
Niche: The specific role or function of a species within an ecosystem.
Life Zone: A region with similar climate and vegetation, resulting in a distinct array of species.
Flyway: A migration route used by birds during seasonal movements.
Boreal: Referring to the northern regions of the world, characterized by cold climates and coniferous forests.
Xeric: Characterized by arid conditions.
Insularity: The state of being geographically isolated, such as an island.
Interspecific Hybrid: An offspring resulting from the breeding of two different species.

Examples:

Sierra del Carmen Isolation: The Sierra del Carmen, a mountainous region in northwestern Coahuila, is separated from other similar areas by vast stretches of desert, leading to the isolation of bird populations.
Ladder-backed Woodpecker Niche Expansion: In the absence of Hairy Woodpeckers in the Sierra del Carmen, the Ladder-backed Woodpecker has expanded its ecological niche, potentially contributing to subspecific variation.
Phainopepla Breeding: The observation of a male Phainopepla with enlarged testes in April suggests breeding in Coahuila.
Golden-fronted Woodpecker Intergradation: The presence of Golden-fronted Woodpeckers with characteristics of both aurifrons and incanescens highlights the intergradation between these subspecies in Coahuila.
Black-eared Bushtit Intergradation: The Black-eared Bushtit subspecies, lloydi and iulus, are known to intergrade in Coahuila, with specimens from the Sierra Guadalupe exhibiting characteristics of both subspecies.
Mexican Jay Abundance: The Mexican Jay is exceptionally common in the Sierra del Carmen, with its abundance reflecting the suitability of the region’s oak and pine-oak habitats.
White-necked Raven Breeding: The collection of White-necked Ravens with enlarged testes in May and June provides evidence of breeding in Coahuila.
Painted Redstart Breeding: The observation of a male Painted Redstart with enlarged testes in April, coupled with the presence of fledglings in the Sierra del Carmen, indicates breeding in the region.
Yellow-throated Vireo Range Extension: The observation of a Yellow-throated Vireo with enlarged testes in June in Coahuila potentially suggests a southward range expansion.
Summer Tanager Subspecies Variation: The presence of Summer Tanagers with characteristics of both rubra and cooperi demonstrates the intergradation between these subspecies in Coahuila.

Conclusion:

This 1959 report provides a valuable glimpse into the rich and diverse avifauna of Coahuila, Mexico. The paper’s key takeaways highlight the influence of geography and climate on bird distribution, the historical origins of the state’s avian heritage, and the fascinating adaptations that have evolved in response to the region’s unique ecological pressures. The text underscores the importance of considering historical factors and environmental influences in understanding bird populations and the processes of speciation. For anyone interested in the fascinating world of birds, the publication offers a compelling and informative account of the avian diversity found in Coahuila, a region that continues to captivate ornithologists with its unique blend of species.

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