The red wolf (Canis rufus) is a canine native to the southeastern United States. Its size is intermediate between the coyote (Canis latrans) and gray wolf (Canis lupus).
The red wolf's taxonomic classification as a species has been contentious for nearly a century, being considered either a subspecies of the gray wolf or a coywolf (a genetic admixture of coyote and wolf). Although this has caused its exclusion from some conservation lists, in 1973 the U.S. Fish and Wildlife Service recognized it as endangered and in 1996 the International Union for Conservation of Nature listed it as critically endangered. There are perhaps around 30 red wolves in the wild, in addition to those in captivity.
Description
The red wolf's appearance is typical of the genus Canis. It is generally intermediate in size between the coyote and gray wolf, though some specimens may overlap in size with small gray wolves. A study of Canis morphometrics conducted in eastern North Carolina reported that red wolves are morphometrically distinct from coyotes and hybrids. Adults measure in length, including the tail, which is about long. Their weight ranges from , with males averaging and females .
Its pelage is typically more reddish and sparsely furred than the coyote's and gray wolf's, though melanistic individuals do occur. Its fur is generally tawny to grayish in color, with light markings around the lips and eyes. The red wolf has been compared by some authors to the greyhound in general form, owing to its relatively long and slender limbs. The ears are also proportionately larger than the coyote's and gray wolf's. The skull is typically narrow, with a long and slender rostrum, a small braincase and a well developed sagittal crest. Its cerebellum is unlike that of other Canis species, being closer in form to that of canids of the Vulpes and Urocyon genera, thus indicating that the red wolf is one of the more plesiomorphic members of its genus.
The red wolf is more sociable than the coyote, but less so than the gray wolf. It mates in January–February, with an average of 6–7 pups being born in March, April, and May. It is monogamous, with both parents participating in the rearing of young. Denning sites include hollow tree trunks, along stream banks and the abandoned earths of other animals. By the age of six weeks, the pups distance themselves from the den, and reach full size at the age of one year, becoming sexually mature two years later.
Using long-term data on red wolf individuals of known pedigree, it was found that inbreeding among first-degree relatives was rare. A likely mechanism for avoidance of inbreeding is independent dispersal trajectories from the natal pack. Many of the young wolves spend time alone or in small non-breeding packs composed of unrelated individuals. The union of two unrelated individuals in a new home range is the predominant pattern of breeding pair formation. Inbreeding is avoided because it results in progeny with reduced fitness (inbreeding depression) that is predominantly caused by the homozygous expression of recessive deleterious alleles.
Taxonomy
The taxonomic status of the red wolf is debated. It has been described as either a species with a distinct lineage, a recent hybrid of the gray wolf and the coyote, an ancient hybrid of the gray wolf and the coyote which warrants species status, or a distinct species that has undergone recent hybridization with the coyote.
The naturalists John James Audubon and John Bachman were the first to suggest that the wolves of the southern United States were different from wolves in its other regions. In 1851, they recorded the "Black American Wolf" as C. l. var. ater that existed in Florida, South Carolina, North Carolina, Kentucky, southern Indiana, southern Missouri, Louisiana, and northern Texas. They also recorded the "Red Texan Wolf" as C. l. var. rufus that existed from northern Arkansas, through Texas, and into Mexico. In 1912, the zoologist Gerrit Smith Miller Jr. noted that the designation ater was unavailable and recorded these wolves as C. l. floridanus.
In 1937, the zoologist Edward Alphonso Goldman proposed a new species of wolf Canis rufus. Three subspecies of red wolf were originally recognized by Goldman, with two of these subspecies now being extinct. The Florida black wolf (Canis rufus floridanus) (Maine to Florida) has been extinct since 1908 and the Texas red wolf (Canis rufus rufus) (south-central US) was declared extinct by 1970. By the 1970s, the Mississippi Valley red wolf (Canis rufus gregoryi) existed only in the coastal prairies and marshes of extreme southeastern Texas and southwestern Louisiana. These were removed from the wild to form a captive breeding program and reintroduced into eastern North Carolina in 1987.
In 1967, the zoologists Barbara Lawrence and William H. Bossert believed that the case for classifying C. rufus as a species was based too heavily on the small red wolves of central Texas, from where it was known that there existed hybridization with the coyote. They said that if an adequate number of specimens had been included from Florida, then the separation of C. rufus from C. lupus would have been unlikely. The taxonomic reference Catalogue of Life classifies the red wolf as a subspecies of Canis lupus.
In 2021, the American Society of Mammalogists considered the red wolf as its own species (Canis rufus).
Taxonomic debate When European settlers first arrived to North America, the coyote's range was limited to the western half of the continent. They existed in the arid areas and across the open plains, including the prairie regions of the midwestern states. Early explorers found some in Indiana and Wisconsin. From the mid-1800s onward, coyotes began expanding beyond their original range.
The taxonomic debate regarding North American wolves can be summarised as follows:
Fossil evidence The paleontologist Ronald M. Nowak notes that the oldest fossil remains of the red wolf are 10,000 years old and were found in Florida near Melbourne, Brevard County, Withlacoochee River, Citrus County, and Devil's Den Cave, Levy County. He notes that there are only a few, but questionable, fossil remains of the gray wolf found in the southeastern states. He proposes that following the extinction of the dire wolf, the coyote appears to have been displaced from the southeastern US by the red wolf until the last century, when the extirpation of wolves allowed the coyote to expand its range. He also proposes that the ancestor of all North American and Eurasian wolves was C. mosbachensis, which lived in the Middle Pleistocene 700,000–300,000 years ago.
C. mosbachensis was a wolf that once lived across Eurasia before going extinct. It was smaller than most North American wolf populations and smaller than C. rufus, and has been described as being similar in size to the small Indian wolf, Canis lupus pallipes. He further proposes that C. mosbachensis invaded North America where it became isolated by the later glaciation and there gave rise to C. rufus. In Eurasia, C. mosbachensis evolved into C. lupus, which later invaded North America.
The paleontologist and expert on the genus Canis natural history, Xiaoming Wang, looked at red wolf fossil material but could not state if it was, or was not, a separate species. He said that Nowak had put together more morphometric data on red wolves than anybody else, but Nowak's statistical analysis of the data revealed a red wolf that is difficult to deal with. Wang proposes that studies of ancient DNA taken from fossils might help settle the debate. In 2009, Tedford, Wang and Taylor reclassified the purported red wolf fossils as Canis armbrusteri and Canis edwardii.
Morphological evidence
In 1771, the English naturalist Mark Catesby referred to Florida and the Carolinas when he wrote that "The Wolves in America are like those of Europe, in shape and colour, but are somewhat smaller." They were described as being more timid and less voracious. In 1791, the American naturalist William Bartram wrote in his book Travels about a wolf which he had encountered in Florida that was larger than a dog, but was black in contrast to the larger yellow-brown wolves of Pennsylvania and Canada. In 1851, the naturalists John James Audubon and John Bachman described the "Red Texan Wolf" in detail. They noted that it could be found in Florida and other southeastern states, but it differed from other North American wolves and named it Canis lupus rufus. It was described as being more fox-like than the gray wolf, but retaining the same "sneaking, cowardly, yet ferocious disposition".
In 1905, the mammalogist Vernon Bailey referred to the "Texan Red Wolf" with the first use of the name Canis rufus. In 1937, the zoologist Edward Goldman undertook a morphological study of southeastern wolf specimens. He noted that their skulls and dentition differed from those of gray wolves and closely approached those of coyotes. He identified the specimens as all belonging to the one species which he referred to as Canis rufus. Goldman then examined a large number of southeastern wolf specimens and identified three subspecies, noting that their colors ranged from black, gray, and cinnamon-buff.
It is difficult to distinguish the red wolf from a red wolf × coyote hybrid. During the 1960s, two studies of the skull morphology of wild Canis in the southeastern states found them to belong to the red wolf, the coyote, or many variations in between. The conclusion was that there has been recent massive hybridization with the coyote. In contrast, another 1960s study of Canis morphology concluded that the red wolf, eastern wolf, and domestic dog were closer to the gray wolf than the coyote, while still remaining clearly distinctive from each other. The study regarded these 3 canines as subspecies of the gray wolf. However, the study noted that "red wolf" specimens taken from the edge of their range which they shared with the coyote could not be attributed to any one species because the cranial variation was very wide. The study proposed further research to ascertain if hybridization had occurred.
In 1971, a study of the skulls of C. rufus, C. lupus and C. latrans indicated that C. rufus was distinguishable by being in size and shape midway between the gray wolf and the coyote. A re-examination of museum canine skulls collected from central Texas between 1915 and 1918 showed variations spanning from C. rufus through to C. latrans. The study proposes that by 1930 due to human habitat modification, the red wolf had disappeared from this region and had been replaced by a hybrid swarm. By 1969, this hybrid swarm was moving eastwards into eastern Texas and Louisiana.
In the late 19th century, sheep farmers in Kerr County, Texas, stated that the coyotes in the region were larger than normal coyotes, and they believed that they were a gray wolf and coyote cross. In 1970, the wolf mammalogist L. David Mech proposed that the red wolf was a hybrid of the gray wolf and coyote. However, a 1971 study compared the cerebellum within the brain of six Canis species and found that the cerebellum of the red wolf indicated a distinct species, was closest to that of the gray wolf, but in contrast indicated some characteristics that were more primitive than those found in any of the other Canis species. In 2014, a three-dimensional morphometrics study of Canis species accepted only six red wolf specimens for analysis from those on offer, due to the impact of hybridization on the others.
DNA studies Different DNA studies may give conflicting results because of the specimens selected, the technology used, and the assumptions made by the researchers.