The volcano rabbit (''Romerolagus diazi'') (), also known as the teporingo or zacatuche, is a small

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

in the family

Leporidae Leporidae () is the family of rabbits and hares, containing over 70 species of extant mammals in all. The family name comes from "Lepus", hare in Latin. Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae ...

that resides on the slopes of

volcanoes A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. It is the only species in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Romerolagus''. It has small rounded ears, short legs, a large forehead, and short, thick fur. Adult rabbits can weigh from . The volcano rabbit lives in groups of 2 to 5 animals in burrows (underground nests) and runways among bunchgrasses. Up to 3 young are produced per litter, born in nests formed from shallow depressions in the ground lined with fur and plant matter. Uniquely among the rabbits, the volcano rabbit emits high-pitched sounds to warn other rabbits of danger, a habit common in the related

pikas A pika ( , or ) is a small, mountain-dwelling mammal native to Asia and North America. With short limbs, a very round body, an even coat of fur, and no external tail, they resemble their close relative the rabbit, but with short, rounded ears. ...

. It is awake and most active in the evening and early morning. Populations have been estimated as approximately 7,000 adult individuals over their entire range. Human developments surrounding the volcano rabbit's habitat, including

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature ...

, hunting, and burning of the species' preferred scrublands have caused significant declines in population, even in protected parks. Both the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

and the

Mexican government The Federal government of Mexico (alternately known as the Government of the Republic or ' or ') is the national government of the United Mexican States, the central government established by its constitution to share sovereignty over the republ ...

consider the volcano rabbit an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

, and it is listed on Appendix I of the

CITES CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

treaty, which is intended to restrict trade of the animal.

Taxonomy and etymology

''Romerolagus diazi'' was first described by the head of the Mexican Geographical and Exploring Commission,

Fernando Ferrari-Pérez Fernando Ferrari-Pérez (1857–1933) was a Mexican academic and biologist. Appointed head of the Mexican Geographical and Exploring Commission in the early 1880s, he was given a commission to catalogue the native mammals, birds, reptiles, fishes ...

, in 1893 as a member of the hares (genus ''Lepus''), using the

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''Lepus diazi'' and common name (volcano rabbit). The

species name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

''diazi'' honors the Mexican

cartographer Cartography (; from , 'papyrus, sheet of paper, map'; and , 'write') is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an imagined reality) can ...

Agustín Díaz, who published the work where the species was first described. Its type locality was "near San Martín Texmelusán, northeastern slope of Volcán Iztaccíhuatl xtaccíhuatl, Puebla Mexico". It was separately described as the Popocatepetl rabbit, ''Romerolagus nelsoni'', in 1896 by American zoologist

Clinton Hart Merriam Clinton Hart Merriam (December 5, 1855 – March 19, 1942) was an American zoologist, mammalogist, ornithologist, entomologist, ecologist, ethnographer, geographer, natural history, naturalist and physician. He was commonly known as the "father o ...

in an account that made no reference to the earlier work of Ferrari-Pérez. The article noted a type specimen that was collected at " Mt. Popocatepetl, Mexico (altitude 3,350 meters or 11,000 feet)" by Edward William Nelson, an American naturalist for whom the species was named. Merriam noted several characteristics that differed significantly from any member of the hares, such as its anatomy and means of locomotion (running on all four legs rather than hopping), and gave it the

name ''Romerolagus'' in honor of Matías Romero, a supporter of the United States Biological Survey in Mexico. It was given its current common and scientific names by the American zoologist Gerrit Smith Miller Jr. in 1911, who noted the discrepancy between the two descriptions and, after consulting with Nelson and Ferrari-Pérez, clarified the nomenclature of the species. From this point up until the 1950s, the

authority Authority is commonly understood as the legitimate power of a person or group of other people. In a civil state, ''authority'' may be practiced by legislative, executive, and judicial branches of government,''The New Fontana Dictionary of M ...

of the species was attributed to Díaz alone; biologist Paulino Rojas Mendoza argued in 1952 that the correct name would be one that credits Ferrari-Pérez as well, which has been accepted ever since. The volcano rabbit is named for its preferred habitat, that being the slopes of

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

es. One

Nahuatl Nahuatl ( ; ), Aztec, or Mexicano is a language or, by some definitions, a group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about Nahuas, most of whom live mainly in Central Mexico and have smaller popul ...

name, , refers to the rabbit's relationship with subalpine tussock grass in the genus ''

Festuca ''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on ...

'' (referred to as in Spanish, in Nahuatl). The name comes from the combination of and (), and has been modified to the currently-used epithet ''zacatuche'' (). Another common name, ''teporingo'', likely derives from

Classical Nahuatl Classical Nahuatl, also known simply as Aztec or Codical Nahuatl (if it refers to the variants employed in the Mesoamerican Codices through the medium of Aztec Hieroglyphs) and Colonial Nahuatl (if written in Post-conquest documents in the Lat ...

, combining (), () and the

suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns and adjectives, and verb endings, which form the conjugation of verbs. Suffixes can ca ...

''-'' referring to location.

Phylogeny

No subspecies of the volcano rabbit are recognized, and it is the only species within its genus. No

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

of the volcano rabbit are known, but analysis of its morphology and genetic records indicate that it is the most basal, or most primitive, species among the leporids, first appearing during the

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

. The species has high

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

and is separated into five

haplogroup A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup (haploid from the , ''haploûs'', "onefold, simple" and ) is a group of similar haplotypes that share a common ancestor with a sing ...

s across its distribution; these groups appear to have some level of

gene flow In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic variation, genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent ...

between them due to the short distance between populations. The volcano rabbit's

sister clade In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

, the group that makes up the species' closest relatives, includes the

European rabbit The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (Spain, Portugal and Andorra) and southwestern France. It is the only extant species in the genus ''Oryctolagus''. The European rab ...

(''Oryctolagus cuniculus'') and the

hare Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live Solitary animal, solitarily or in pairs. They nest in slight depressions called forms, and their young are precociality, able to fend for themselves ...

s (in genus ''Lepus''). The following

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

is based on mitochondrial genome analysis of the volcano rabbit, the European rabbit, the

snowshoe hare The snowshoe hare (''Lepus americanus''), also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sink ...

(''Lepus americanus''), and the black-tailed jackrabbit (''Lepus californicus''), as well as a broader

phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...

produced by biologist Leandro Iraçabal Nunes and colleagues:

Characteristics

The volcano rabbit is one of the smallest rabbits in the world, having an adult weight that ranges from and a total length of . Its ears are small and rounded, measuring less than , and the hind feet are short (only ). Its small size relates to its selective dietary habits. The base color of the rabbit's fur has been described as " antimony yellow". Its short, dense fur ranges in color from brown to black, with the dorsal fur coat (on the back of the animal) being yellowish brown and black at the tips. Fur on the rabbit's underside is soft and dense, but has the same color as the dorsal fur. The dark coloration of the volcano rabbit's fur blends in with the volcanic soils in its habitat, an adaptation that may help it evade predators. The coat does not change color from one season to the next, though it does undergo molting over the course of the year in four stages. First, hair is lost, then

melanin Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...

disappears, then melanin is deposited at the site of hair loss, after which hair regrows. The volcano rabbit strongly resembles

pika A pika ( , or ) is a small, mountain-dwelling mammal native to Asia and North America. With short limbs, a very round body, an even coat of fur, and no external tail, they resemble their close relative the rabbit, but with short, rounded ears. ...

s, closely related mountain-dwelling

lagomorph The lagomorphs () are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

s. The skull of the volcano rabbit has small triangle-shaped projections from the

brow ridge The brow ridge, or supraorbital ridge known as superciliary arch in medicine, is a bony ridge located above the eye sockets of all primates and some other animals. In humans, the eyebrows are located on their lower margin. Structure The brow ri ...

towards the back of the head. It has a long

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

, and a distinctly separated interparietal bone. The

cheekbone In the human skull, the zygomatic bone (from ), also called cheekbone or malar bone, is a paired irregular bone, situated at the upper and lateral part of the face and forming part of the lateral wall and floor of the orbit (anatomy), orbit, of t ...

s are wide, larger towards the back of the head, and the

auditory bulla The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympanic b ...

e (bony structures that enclose the external structure of the ear) are large compared to those of other

leporid Leporidae () is the family of rabbits and hares, containing over 70 species of extant mammals in all. The family name comes from "Lepus", hare in Latin. Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae ...

s—larger than the

foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...

(the hole at the base of the skull that the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

passes through), though the tympanic bullae (which enclose the internal ear structure) are relatively normal. The

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

is complete, and connects to the

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

directly; the bone structure at the front of the sternum is wider than it is long. The central part of the sternum is segmented into 3 parts, which are articulated with 6 pairs of the

ribs The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels ...

. The

pituitary gland The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the human brain, brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus contr ...

is small, and connects to the first three

lumbar vertebrae The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...

. The rabbit's

navicular bone The navicular bone is a small bone found in the feet of most mammals. Human anatomy The navicular bone in humans is one of the tarsus (skeleton), tarsal bones, found in the foot. Its name derives from the human bone's resemblance to a small ...

is short and does not extend below the

metatarsal bones The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

. Like other leporids, it has a

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

of —two pairs of upper and one pair of lower

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s, no canines, three upper and two lower

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

s on each side, and three upper and lower

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

on either side of the jaw. Their

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

s resemble those of other rabbits. The rabbit's morphological features resemble those of several extinct leporids from the

Tertiary period The Tertiary ( ) is an obsolete Period (geology), geologic period spanning 66 million to 2.6 or 1.8 million years ago. The period began with the extinction of the non-bird, avian dinosaurs in the Cretaceous–Paleogene extinction event, at t ...

, including '' Nekrolagus'', which lived during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58

Distribution and habitat

Volcano rabbits are endemic to Mexico. Specifically, the rabbit is native to the alpine

scrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominance (ecology), dominated by shrubs, often also including grasses, herbaceous plant, herbs, and geophytes. Shrubland may either occur naturally o ...

s surrounding four volcanoes ( Cerro Tláloc, Popocatépetl, Iztaccíhuatl, and El Pelado) just southeast of Mexico City in an area of only . The largest of these volcanic regions is within the

Iztaccíhuatl–Popocatépetl National Park Iztaccíhuatl–Popocatépetl National Park, also known as Izta-Popo Zoquiapan National Park, is a national park in Mexico on the border of the states of México, Puebla, and Morelos. The park protects , surrounding Mexico's second- and third-high ...

, with other areas including the Chichinautzin and Pelado volcanoes. Historically, the volcano rabbit likely occupied the

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

and Sierra Chichinautzin mountain ranges. The range of the volcano rabbit has since been fragmented into 16 (later 19) individual patches across the

Trans-Mexican Volcanic Belt The Trans-Mexican Volcanic Belt (), also known as the Transvolcanic Belt and locally as the (''Snowy Mountain Range''), is an active volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and dur ...

due to human disturbance. Volcano rabbits are commonly found at altitudes between , but can occur anywhere from . The soil of the volcano rabbit's habitat consists mostly of andosols and lithosols, and the vegetation includes

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America ...

and

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

varieties. The local climate is temperate, subhumid, and has a mean annual temperature of . Annual rainfall averages at about . The plants ''Festuca tolucensis'' and '' Pinus hartwegii'' are abundant in volcano rabbit habitats. The species prefers habitats with tall, dense vegetation from a variety of "" bunch grasses, such as '' Muhlenbergia macroura'' and '' Festuca amplissima''. Volcano rabbits show strong preferences for open pine forests, open pine woodland, and mixed alder pine forest habitats. Human activity in the area has had a great impact upon the preferred habitat of the volcano rabbit, as its habitat has been fragmented by highways, farming,

afforestation Afforestation is the establishment of a forest or stand of trees in an area where there was no recent tree cover. There are three types of afforestation: natural Regeneration (biology), regeneration, agroforestry and Tree plantation, tree plan ...

, and unsound fire and grazing practices. A study on the

effects of climate change Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an Instrumental temperature record, overall warming trend, Effects of climate change on the ...

upon volcano rabbit populations concluded that fluctuations in climate affected rabbits more on the edge of their habitable range. The volcano rabbit was once considered to live in the

Nevado de Toluca Nevado de Toluca () is a stratovolcano in central Mexico, located about west of Mexico City near the city of Toluca. It is the fourth highest of Mexico's peaks, after Pico de Orizaba, Popocatépetl and Iztaccíhuatl. The volcano and the area ...

, but research conducted by Hoth et al., in relation to its distribution in 1987 found no records of this species there, including the site where mammalogist Ticul Álvarez collected a specimen in 1975. Though there was an unconfirmed sighting in the region in August 2003, no permanent volcano rabbit colony has been documented in Nevado de Toluca and it was declared

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

within this portion of its range in 2018. Populations exist elsewhere within the Trans-Mexican Volcanic Belt and in captivity. As of 2019, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

no longer mentions the Nevado de Toluca as a current or potential site for the distribution of this species.

Behavior and ecology

The volcano rabbit lives in groups of 2 to 5 individuals, and creates runways similar to those made by microtine rodents to navigate their habitat. Its burrows consist of tunnels with the entrances hidden under dense grass clumps or in cracks in the soil, and can have a length of up to and depth of up to under the soil's surface. These burrows may have other entrances to allow for escape, and the tunnels often weave around rocks and roots. Volcano rabbits may opportunistically use burrows abandoned by other mammals, such as

gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...

s and

badger Badgers are medium-sized short-legged omnivores in the superfamily Musteloidea. Badgers are a polyphyletic rather than a natural taxonomic grouping, being united by their squat bodies and adaptions for fossorial activity rather than by the ...

s, as do other rabbits besides the European rabbit. It has very developed hind limbs relative to its body size, which correlates to a need to make evasive actions. It is relatively slow and vulnerable in open habitats; therefore it takes comfort in high, covered areas. The volcano rabbit produces high-pitched vocalizations to warn others in its group of danger, a behavior unique among the rabbits, but similar to those produced by pikas. Little is known about its longevity, and it is expected to have an average lifespan of less than a year in the wild, like other rabbits and hares. It is most active in the evening and early morning, though large groups of volcano rabbits have been spotted outside their burrows just around noon. The reproductive behavior of volcano rabbits has been infrequently observed, with most records coming from individuals in captivity. Males will often select a single female out of a group to mate with, though when this mate is taken away they will choose another. The mating process begins with the male following closely behind its partner until the female turns around, at which point the two start circling around each other. After a few turns, the male mounts the female and begins copulation. The species has a very narrow gestational period. In a 1985 study, all females gave birth between 39 and 41 days after coitus; later works note the gestational period as 39 days. Up to three young are produced per litter, with 4 to 5 litters produced per year. The young wean off the mother until they are roughly 28 days old, and reach sexual maturity after 185 days. The species is sexually active year-round, though the period of greatest activity is during the summer. Their nests, shallow depressions dug in the ground lined with shredded grasses, plant fragments, and fur, are built only from April to September. These nests are in depth and wide. This nesting behavior is similar to that of female

cottontail rabbit Cottontail rabbits are in the ''Sylvilagus'' genus, which is in the family Leporidae. They are found in the Americas. Most ''Sylvilagus'' species have stub tails with white undersides that show when they retreat, giving them their characterist ...

s. The young are delivered in these nests, similar to burrowing rabbits which give birth in a nesting chamber. The volcano rabbit is noted as having difficulty breeding in small enclosures.

Diet

The volcano rabbit feeds primarily on grasses such as '' Festuca amplissima'', ''Muhlenbergia macroura'', '' Jarava ichu'', and ''Eryngium rosei''. The rabbits also use these plants as cover to hide from predators. ''M. macroura'' has been found in 89% of volcano rabbit pellets in one study, suggesting that this is the base of their diet, but it does not actually provide the necessary energy and protein needs of the rabbits. The rest of the rabbit's required nutrition is obtained from 15 other forms of plant life, including ''M. quadidentata'', ''Pinus hartwegii'', ''F. tolucensis'', ''Alchemilla sibbaldiifolia'', ''Museniopsis arguta'' and ''Cunila tritifolium''. Volcano rabbits also consume leaves, foliage, and flowers indiscriminately when unable to access their preferred foods. Habitat loss has caused many of these food sources to become inaccessible to the rabbit. Protein acquisition is the primary limiting factor on population sizes, and many individuals suffer from serious weight loss and starvation due to poor nutrition. Seasonal changes affect the diet of the volcano rabbit greatly. The grasses it normally consumes are abundant during wet seasons. During the dry season, the volcano rabbit eats the leaves of shrubs and small trees, as well as other woody plants. In winter, woody plants make up most of their diet, and provide the primary building material for their nests. In captivity, volcano rabbits are often given pellet food typical for

chinchillas Chinchilla refers to either of two species ('' Chinchilla chinchilla'' and '' Chinchilla lanigera'') of crepuscular rodents of the parvorder Caviomorpha, and are native to the Andes mountains in South America. They live in colonies called "her ...

Predators and parasites

The volcano rabbit is

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

for several species; in Iztaccíhuatl–Popocatépetl National Park, it makes up 12.5% of prey for the

bobcat The bobcat (''Lynx rufus''), also known as the wildcat, bay lynx, or red lynx, is one of the four extant species within the medium-sized wild cat genus '' Lynx''. Native to North America, it ranges from southern Canada through most of the c ...

, and 5.5% for the

coyote The coyote (''Canis latrans''), also known as the American jackal, prairie wolf, or brush wolf, is a species of canis, canine native to North America. It is smaller than its close relative, the Wolf, gray wolf, and slightly smaller than the c ...

Long-tailed weasel The long-tailed weasel (''Neogale frenata''), also known as the bridled weasel, masked ermine, or big stoat, is a species of weasel found in North America, North, Central America, Central, and South America. It is distinct from the Stoat, short-t ...

red-tailed hawk The red-tailed hawk (''Buteo jamaicensis'') is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members of ...

s, and

rattlesnake Rattlesnakes are venomous snakes that form the genus, genera ''Crotalus'' and ''Sistrurus'' of the subfamily Crotalinae (the pit vipers). All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting sm ...

s are also significant predators. Feral dogs present around villages may also prey upon the volcano rabbit.

Nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

cestode Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies co ...

flea Flea, the common name for the order (biology), order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by hematophagy, ingesting the blood of their hosts. Adult f ...

s and

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s affect the volcano rabbit, several of which are species-specific. It is parasitized by the mites ''Cheyletiella mexicana'' and ''Cheyletiella parasitovorax'', which is notable as mites in genus '' Cheyletiella'' do not tend to occur on the same host. Other species-specific parasites are ''Boreostrongylus romerolagi'', ''Dermatoxys romerolagi'', ''Lamothiella romerolagi'', ''Anoplocephaloides romerolagi'', ''Cediopsylla tepolita'', ''Hoplopsyllus pectinatus''. Ticks (in family Ixodidae), chiggers (in family Trombiculidae), and botfly larvae (in family Cuterebridae) have also been found on wild volcano rabbits.

Status and conservation

Threats to ''R. diazi'' include logging, harvesting of grasses, livestock grazing,

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, urban expansion, highway construction and frequent forest fires. Unsound management policies of its habitat in National Parks and outside, mainly by afforestation, have also threatened volcano rabbit populations. The IUCN estimated in 2019 that roughly 7,000 rabbits remained in the wild, and noted that the population was decreasing. Prior studies placed this population number between 11,000 and 25,000 individuals.

Captive breeding Captive breeding, also known as captive propagation, is the process of keeping plants or animals in controlled environments, such as wildlife reserves, zoos, Botanical garden, botanic gardens, and other Conservation biology, conservation facilitie ...

programs have been established with varying success, but infant mortality in captivity is high. Human developments on lands inhabited by the volcano rabbit, as well as the effects of human-caused climate change, have caused declines in population.

Threats and decline

Numerous studies conducted during the 1980s and 1990s agreed that the habitat of the volcano rabbit was shrinking due to a combination of natural and anthropogenic causes. There is evidence that its range has shrunk significantly during the last 18,000 years due to a increase in temperature.

Habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...

is a common cause of population decline in Mexican mammals, and the volcano rabbit is particularly affected due to its specific habitat and diet needs. Patches of vegetation that ''R. diazi'' uses for survival are becoming more isolated and smaller, rendering the environment more open and therefore less suitable for its survival. Because the volcano rabbit inhabits the area surrounding Mexico City, Mexico's most populous region, it has suffered a very high rate of

. Additionally, human disturbances enable other rabbit species to flourish in grasslands, increasing competition with the volcano rabbit. Cottontail rabbits have expanded into regions occupied by the volcano rabbit, though it is unclear if the volcano rabbit is being pushed to their mountain habitats due to competition from other species. Climate change has been cited as a potentially damaging factor to the volcano rabbit, as increasing temperature causes the species to move to higher elevations where the habitat is less suitable overall. Hunting is another threat to the volcano rabbit, despite the fact that ''R. diazi'' is listed under Appendix 1 of

, a treaty that severely restricts the trade of listed species. It is illegal to hunt under Mexican law, but this hunting law is poorly enforced, and regions inhabited by the volcano rabbit have been largely abandoned by law enforcement. The species is hunted despite the fact that its small size and rough fur makes it a very poor source of meat and skins. Hunting, livestock grazing, and fires can harm ''R. diazi'' even within the boundaries of national parks.

Conservation

Volcano rabbits have been bred in captivity, but there is evidence that the species loses a significant amount of genetic diversity when it reproduces in such conditions. A comparative study done on wild and captive volcano rabbits found that the latter lost a substantial amount of DNA loci, and some specimens lost 88% of their genetic variability. There was, however, one locus whose variability was higher than that of the wild population. The IUCN created an action plan for the volcano rabbit in 1990 that focuses upon the need to manage the burning and

of grassland habitats and to enforce laws prohibiting its hunting, capture, and sale. Studies about the volcano rabbit's geographical range, role in its habitat, population dynamics, and evolutionary history were recommended. Some populations have been able to recover due to volanic activity at Popocatepetl, which has restricted incursions by herders and tourists. The IUCN currently lists the volcano rabbit as an

, as does the Mexican government through the Secretariat of Environment and Natural Resources.

References

Sources

* * *

External links

These Endangered Rabbits Live on the Slope of a Mexican Volcano
- 1992 documentary on the volcano rabbit
A Survival Blueprint for the conservation of the Volcano rabbit ''Romerolagus diazi'' and its habitat
- EDGE of Existence programme publication {{Authority control Rabbits EDGE species Endemic mammals of Mexico Mammals described in 1893 Taxa named by Fernando Ferrari-Pérez Fauna of the Trans-Mexican Volcanic Belt