The family Cervidae, commonly referred to as "the deer family", consists of 23 genera containing 47 species, and includes three subfamilies: Capriolinae (brocket deer, caribou, deer, moose, and relatives), Cervinae elk, muntjacs, and tufted deer), and Hydropotinae, which contains only one extant species, Chinese water deer. However, classification of cervids has been controversial and a single well-supported phylogenetic and taxonomic history has yet to be established. Cervids range in mass from 20 lbs to 1800 lbs, and all but one species, Chinese water deer, have antlers. With the exception of caribou, only males have antlers and some species with smaller antlers have enlarged upper canines. In addition to sexually dimorphic ornamentation, most deer species are size-dimorphic as well with males commonly being 25% larger than their female counterparts. Cervids have a large number of morphological synapomorphies (e.g., characteristics that are shared within a taxonomic group), and range in color from dark to very light brown; however, young are commonly born with cryptic coloration, such as white spots, that helps camouflage them from potential predators. Cervids can be found in a wide range of habitats, from extremely cold to the tropics. They have been introduced nearly world wide, but are native throughout most of the New World, Europe, Asia and northwestern Africa, with Eurasia exhibiting the greatest species diversity. Although most cervids live in herds, some species, such as South American marsh deer, are solitary. The majority of species have social hierarchies that have a positive correlation with body size (e.g., large males are dominant to small males). (Feldhamer, et al., 2007; Fulbright and Ortega-S., 2006; Herna ́ndez Ferna ́ndez and Vrba, 2005; Huffman, 2010; Vaughan, et al., 2000)

Geographic Range

Cervids are widely distributed and are native to all continents except Australia, Antarctica, and most of Africa, which contains only a single sub-species of native deer, Barbary red deer. Cervids have been introduced nearly worldwide and there are now 6 introduced species of deer in Australia and New Zealand that have been established since the mid 1800s. (Bauer, 1985; Feldhamer, et al., 2007; Huffman, 2010; Vaughan, et al., 2000)


Cervids live in a variety of habitats, ranging from the frozen tundra of northern Canada and Greenland to the equatorial rain forests of India, which has the largest number of deer species in the world. They inhabit deciduous forests, wetlands, grasslands, arid scrublands, rain forests, and are particularly well suited for boreal and alpine ecosystems. Many species are particularly fond of forest-grassland ecotones and are known to reside a variety of urban and suburban settings. (Feldhamer, et al., 2007; Fulbright and Ortega-S., 2006; Vaughan, et al., 2000)

Physical Description

There is a great deal of physical diversity within the family Cervidae. Moose, the largest extant member of the family, can reach up to 1800 lbs and the smallest, northern pudu, reach a maximum size of roughly 20 lbs. Typically members have compact torsos and very powerful elongated legs that are well suited for woody or rocky terrain. With the exception of Chinese water deer, all male cervids have deciduous antlers and caribou are the only species in which both males and females have antlers. Deer are primarily browsers (foraging on broad leaf plant material), and their low- (brachydont) to medium-crowned (mesodont) selenodont cheek teeth are highly specialized for browsing. Cervids lack upper incisors and instead have a hard palate. The anterior portion of the palate is covered with a hardened tissue against which the lower incisors and canines occlude. They have a 0/3, 0-1/1, 3/3, 3/3 dental formula. Other notable features of cervids include the lack of a sagittal crest and the presence of a postorbital bar. (Danilkin, 1996; Fulbright and Ortega-S., 2006)

Antlers grow from pedicels, boney supporting structures that grow on the lateral regions of the frontal bones. In temperate-zone cervids, antlers begin growing in the spring as skin-covered projections from the pedicels. The dermal covering, or "velvet," is rich in blood vessels and nerves. When antlers reach full size, the velvet dies and is rubbed off as the animal thrashes its antlers against vegetation. Antlers are used during male-male competition for mates during breeding season, and are shed soon afterwards. Typically, only males bear antlers however, both genders bear antlers in caribou. Antlers vary from simple spikes, such as those in munjacs, to enormous, complexly branched structures, such as those in moose. Antler structure changes depending on species and the age of the individual bearing them. Males of the genus Muntiacuc have both antlers and long, fang-like upper canines that are used in social displays. Although Chinese water deer are the only species without antlers, they have elongated upper canines that are used to attract mates. Antlers typically emerge at one year of age. (Danilkin, 1996; Fulbright and Ortega-S., 2006)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently
  • ornamentation


Although most cervids are polygynous, some species are monogamous (e.g., European Roe deer). The breeding season of most cervids is short, with females coming into estrus in synchrony. In some species, males establish territories, which encompass those of one or more females. Males may then mate with those females who have territories within his own. In some cervids, females may form small groups known as harems, which are guarded and maintained by males, and in other species males simply travel between herds looking for estrus females. Sexual segregation is not uncommon in cervids; however, in some species permanent mixed-sex groups result in male-male competition for potential mates. In sexually segregating species, males join females only to copulate, leaving at the end of breeding season. Males establish dominance hierarchies among themselves, with the most dominant males achieving the most copulations. Males may hold dominance over a harem or territory and are often challenged by rival males. Male cervids significantly decrease forage intake during breeding season, which, in conjunction with being continually challenged by rivals males, ensures that dominance by any one individual is short lived. Antler growth is dependent on individual nutrition and evidence suggests that the size and symmetry of male antlers serves as an indicator of mate quality for females. (Feldhamer, et al., 2007; Miquelle, 1990; Putnam, 1989)

Cervids living in temperate zones typically breed during late autumn or early winter. Seasonal breeders at lower latitudes, such as the chital, breed from late spring into early summer (e.g., April or May). Conception usually occurs during the first estrus cycle of the breeding season, and those that do not conceive will re-enter estrus every 18 days until they become pregnant. Species living in tropical climates, such as grey brocket deer, often do not have a fixed breeding season, and females may come in to estrus multiple times throughout the year. Gestation in cervids ranges from 180 days in Chinese water deer to 240 days for elk, with larger species tending to have longer gestational periods. Roe deer are the only cervid known to have delayed implantation. Cervids typically have from 1 to 3 offspring, and often, not all fetuses are carried to term, as the number of offspring born each year is dependent on population density and resource abundance. Age at weaning varies among species, with smaller species nursing for only 2 to 3 months and larger species nursing for much longer. For example Bornean yellow muntjacs are weaned by about 2 months of age and North American moose are weaned by about 5 months, however, erratic nursing may continue for up to 7 months after birth. (Feldhamer, et al., 2007; Putnam, 1989)

Body weight is more importance in determining sexual maturity in cervids than actual age; therefore, an individual's reproductive activity is dependent on environmental conditions and resource quality and abundance. Due to the energetic costs of lactation, this is especially true for females. In males, testes begin producing hormones at the end of the first year, and consequently, antler growth occurs during the end of the first year or the beginning of the second. However, because male-male competition plays a dominant role in cervid mating behavior, most males do not mate until they can outcompete rivals for access to females. (Feldhamer, et al., 2007; Putnam, 1989)

Although some cervids are solitary, most are gregarious and live in herds that vary in size from a few individuals to more than 100,000 (e.g., caribou. Average group size depends on the demographic composition (i.e., sex and age) of the immediate population, the degree of inter- and intraspecific competition, and resource quality and abundance. Habitat segregation in cervids tends to peak during calving and significantly decreases soon afterward. Most species are polygynous, and males use their antlers in combat to obtain and defend females. Sexual-size dimorphism is common in cervids. Males are larger than females in most species, and sexual dimorphism is more pronounced in the most highly polygynous species. Cervids have a number of glands on their feet, legs, and faces that are used during intraspecific communication. Males of many cervid species significantly decrease forage intake during mating season, and evidence suggests that feeding cessation in males is linked to various physiological processes associated with chemical communication during the breeding season. (Bowyer, et al., 2010; Bubenik, 2007; Feldhamer, et al., 2007; Miquelle, 1990; Vaughan, et al., 2000)

As with many artiodactyls, cervids can be classified as either hiders or followers. Altricially born cervids are highly vulnerable to predation for the first few weeks of life. As a result, mothers hide their young in the surrounding vegetation as they forage nearby. Hider mothers periodically return to their young throughout the day to nurse and clean their calves. Females that give birth to multiple offspring hide each individual in separate locations, presumably to decrease the chance of losing multiple young to a predator. Once young become strong enough to escape potential predators they join their mother during foraging bouts. Some species are precocially born and are able to run only a few hours after birth (e.g., Rangifer tarandus). These species are often referred to as followers. (Feldhamer, et al., 2007; Putnam, 1989)

Lactation is one of the most energetically expensive activities possible for female mammals and lactating cervids are often not able to consume enough food to maintain their body weight, especially during the first weeks of lactation. Typically, young are weaned earlier in smaller species; however, sporadic nursing may occur for up to 7 months after birth. Young cervids may stay with their mother until she is about to give birth to the subsequent season’s offspring. In many species, females stay within their mother’s range after maturation, while males are forced to disperse. In most species, males do not provide any parental care to their offspring. (Feldhamer, et al., 2007; Putnam, 1989)

  • Parental Investment
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents


The lifespan of most cervid ranges from 11 to 12 years, however, many are killed before their fifth birthday due to various causes including hunting, predation, or motor vehicle collisions. In most species, males have shorter lifespans than females and this is likely a result of intrasexual competition for mates and the solitary nature of most sexually dimorphic males, resulting in increased risk of predation. However, recent studies show that sex-biased mortality rates are tightly linked to local environmental conditions. Captive deer tend to outlive their wild counterparts as they are subjected to little or no predation and have access to an abundant supply of food. The lifespan of cervids decreases as the number of deer exceeds the local environments carrying capacity. In this case, young and old cervids tend to suffer from starvation, as stronger, middle-aged deer outcompete them for forage. (Danilkin, 1996; Toigo C, et al., 2003; Whitehead, 1972)


Although active throughout most of the day, cervids are typically classified as crepuscular. Species living in seasonal climates spend most of their time during the winter and early spring resting, as forage during this time is limited and of poor quality. During late spring, when fresh forage is available, deer spend less time resting and significantly increase their activity rates. Activity patterns are based on seasonal metabolic rates and energy costs, which change from season to season. During summer, energy requirements are high and thus they spend more time foraging. Cervids tend to lose weight during winter due to a reduction in appetite and decreased forage quality and availability. However, many species found in habitats with minimal climatic variability exhibit a reduction in food intake and decreased metabolic rate during certain parts of the year. In habitats with abundant resources cervid home-range size does not change between seasons. However, in poor habitats winter ranges expand significantly, presumably to offset the decrease in forage quality and abundance that occurs during winter. Deer are typically more aggressive during food shortages, in areas of high population density, and during mating season. They often make themselves appear more intimidating by raising their body hair (i.e., piloerection) through contraction of the arrector pili muscle, which makes them appear larger. (Bauer, 1985; Danilkin, 1996; Fulbright and Ortega-S., 2006; Hiller, 1996; Putnam, 1989; Whitehead, 1972)

Larger, more aggressive males tend to gain dominance over others, which results in access to females during mating season and consequently, higher reproductive rates. During male-male competition for mates, larger males are dominant, and if two animals are the same size, the individual with the largest set of antlers gains dominance, unless the larger individual is past his prime. In some species, individuals may encircle one another with a stiff-legged stride while making a high-pitched whine or low grunting sound and is meant to intimidate rival individuals. During mating season, male cervids often scrape the ground with their forelimbs to advertise their presence and availability to potential mates. Scrapes are usually made by dominant males and consist of a “sign-in”, which involves chewing on a branches overhanging the scrape, pawing the scrape underneath the branch, and rubbing glandular secretions on the scrape, which advertises his presence. In some cases, males may urinate, ejaculate, or defecate in the scraped area. Females are most aggressive when they have offspring with them. They are very protective of their young and readily defend their offspring against both inter- and intraspecific threats. (Bauer, 1985; Danilkin, 1996; Fulbright and Ortega-S., 2006; Hiller, 1996; Putnam, 1989; Whitehead, 1972)

Social organization in cervids is highly variable and in some cases is based on season. Although most species remain in small groups, large herds may results during feeding, after which individuals tend to disperse. In gregarious cervids, males join calf-cow herds during mating season to mate then quickly return to their solitary lifestyles. During summer, many cervids remain in small groups with some species becoming solitary. During winter, cervids may congregate into larger families or herds, which likely helps reduce vulnerability to predation. Dominant individuals signal their status in the hierarchy with a “hard look”, which involves staring directly at a potential rival while laying their ears back with his or her head lowered. If the rival individual is not willing to challenge for dominance, they slowly back away and refuse eye contact. If the “hard look” is successful, he or she will drop and extend their head toward the subordinate individual, after which a charge may occurs. (Bauer, 1985; Danilkin, 1996; Fulbright and Ortega-S., 2006; Hiller, 1996; Putnam, 1989; Whitehead, 1972)

Similar to other endothermic animals, many cervids migrate according to proximal cues, such as photoperiod. These proximal cues serve as indicators for various ultimate factors, such as changes in season, which can affect the abundance of pests, predators, and forage. Although the costs of migration can be great, benefits often include increased individual survival rates and increased reproductive fitness. One of the best-studied cases of cervid migration is that of barren-ground caribou, which travel an annual distance of more than 500 km. Unfortunately, seasonal migration is cued by photoperiod while onset of plant-growing season is cued by temperature. If the growing season of species-specific resources is not precisely matched to the initiation of migration, changes in plant phenologies may detrimentally impact the long-term survival of migratory animals. For example, increasing mean spring temperatures in West Greenland appear to have resulted in a mismatch between caribou migratory cues and the onset of spring growing season for important forage plants. Evidence suggests that caribou migrations are not advancing at a comparable rate with forage plants and as a result, calf production in West Greenland caribou has decreased by a factor of four. (Darling, 1937; Feldhamer, et al., 2007; Nowak, 1999; Post and Forchhammer, 2008; Scott, 1988; Vaughan, et al., 2000)

Communication and Perception

Cervids use three main types of communication: vocal, chemical, and visual. Vocal communication is used primarily during times of fear or excitement. The most common form of vocal communication is barking, which is typically used in response to a disturbance, such as visual contact with a predator or a disturbing noise. Barking is also used as an expression of victory after a competitive interaction between two males. Cervids also communicate through a variety of hormone and pheromone signals. For example, male cervids demarcate territory with glandular secretions rubbing their face, head, neck, and sides against trees, shrubs, or tall grasses. Cervids also use visual communication, known as scraping. Scraping is primarily used during mating season by males to advertise their presence and availability to females. To create a scape, males paw the ground with the forelimbs, producing patches of bare ground about 0.5 m to 1.0 m in width. Typically, scrapes are marked with a secretion from the interdigital glands located between their hooves. In response to a potential threat, some species stand with their body tensed and rigid, while leaning slightly forward, which signals the potential threat to conspecifics. (Danilkin, 1996; Hiller, 1996; Whitehead, 1972)

Food Habits

All cervids are obligate herbivores with diets including grass, small shrubs, and leaves. In addition to the true stomach, or abomasum, cervids have 3 additional chambers, or false stomachs, in which bacterial fermentation takes place. In ruminants, the digestion of high-fiber, poor-quality food occurs via four different pathways. First, gastric fermentation extracts lipids, proteins, and carbohydrates, which are then absorbed and distributed throughout the body via the intestines. Second, large undigested food particles form into a bolus, or ball of cud, which is regurgitated and re-chewed to help break down the cell wall of ingested plant material. Third, cellulose digestion via bacterial fermentation results in high nitrogen microbes that are occasionally flushed into the intestine, which are subsequently digested by their host. These high-nitrogen microbes serve as an important protein source. Finally, cervids can store large amounts of forage in their stomachs for later digestion. All cervids chew their cud, have three or four-chambered stomachs, and support microorganisms that breakdown cellulose. Unlike many other ruminants, cervids selectively forage on easily digestible vegetation rather than consuming all available food. (Feldhamer, et al., 2007; Putnam, 1989; Van Soest, 1994; Vaughan, et al., 2000; Whitaker and Hamilton, 1998)


In areas where large carnivore populations have not been significantly reduced by humans, predation represents an important cause of mortality for cervids. For many species, predation is the primary means of controlling population densities. For many cervids, predation on calves is especially important in limiting population size, and much of this predation is accomplished by smaller carnivores (e.g., Canada lynx, caracal, and coyote). It is difficult, however, to estimate the natural effect of predation on cervids, as predator populations in many locations have been significantly reduced or eliminated by humans. To avoid predation, gregarious species foraging in open habitats group together to face potential threats. Solitary species avoid predators by foraging in or near the protective cover of woodland or brush habitat. The young of most cervids have spots or stripes on their pelage, which helps camouflage them in dense vegetation. All species give a harsh bark, which serves as an alarm to conspecifics. Pronking (i.e., continuously jumping high into the air) and tail-flaring is a known response to predators at close range, as well as when individuals are startled. Cervids also have acute senses of sight, hearing, and smell, which helps them avoid potential predators. (Putnam, 1989)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Cervids are an important food source for many predators throughout their geographic range. For example, one study showed that over 80% of the feces of gray wolves in Algonquin Park in Canada contained the remains of white-tailed deer. Cervids are host to a variety of endoparasites, including parasitic flatworms (Cestoda and Trematoda) and many species of roundworm (Nematoda) spend at least part of their lifecycle in the tissues of cervid hosts. Cervids are also vulnerable to various forms of parasitic arthropods including ticks (Ixodoidea), lice (Phthiraptera), mites (Psoroptes and Sarcoptes), keds (Hippoboscidae), fleas (Siphonaptera), mosquitoes (Culicidae), and flies (Diptera). In addition, cervids compete with other species for food and other resources, which can effectually limit both inter- and intraspecific population growth. (Escalante and Ayala, 1995; Kutz, et al., 2005; Putnam, 1989; Whitaker and Hamilton, 1998)

Cervids play an integral role in the structure and function of the ecosystems in which they reside, and some species have been shown to alter the density and composition of local plant communities. For example, on Isle Royale National Park, MI, moose (Alces alces) have been shown to alter the density and composition of foraged aquatic plant communities, and fecal nitrogen transferred from aquatic to terrestrial habitats via the ingestion of aquatic macrophytes increases terrestrial nitrogen availability in summer core areas. Foraging by cervids has been shown to have a significant impact on plant succession, and plant diversity is greater in areas subjected to foraging. As a result, foraging might lead to shifts from one plant community type to another (e.g., hardwoods to conifers). In addition, moderate levels of foraging by cervids may increase habitat suitability for conspecifics. For example, litter from foraged plants decomposes more quickly than non-browsed, thus increasing nutrient availability to the surrounding plant community. Moreover, nutrient inputs from urine and feces have been shown to contribute to longer stem growth and larger leaves in the surrounding plant community, which are preferentially fed upon during subsequent foraging bouts. Finally, research has shown that the decomposition of cervid carcasses can result in elevated soil macronutrients and leaf nitrogen for a minimum of two years. (Bowyer, 1997; Bump, J., R. Peterson, J. Vucetich., et al., 2009; Flanagan and Van Cleve, 1983; Molvar, et al., 1993; Pastor, et al., 1993; Risenhoover and Maass, 1987)

Although cervids can be host to numerous species of pathogenic bacteria and protozoa, in conjunction with anaerobic fungi, similar classes of microorganisms are one of the major reasons that cervids are as abundant and diverse as they are today. Bacteria comprise between 60 and 90% of the microbial community present in the ruminant's gastrointestinal (GI) tract and help break down cellulose. Ciliated protozoa, which makes up 10 to 40% of the microbe community within the rumen, help break down cellulose, while also feeding on starches, proteins and bacteria. The presence of anaerobic fungi in the rumen has only been known since the early 1970's. These fungi make up between 5 to 10% of the rumen's microbial abundance and are thought to help break down the cell wall of ingested plant material. Bacteria and protozoa that pass from the upper to the lower regions of the GI tract represent a significant portion of the dietary nitrogen required by their host. (Van Soest, 1994)

  • Ecosystem Impact
  • disperses seeds
Mutualist Species
  • rumen bacteria, (Selenomonads)
  • rumen bacteria, (Oscillospira)
  • rumen protozoa, (Entodinium)
  • rumen protozoa, (Dasytricha)
  • rumen protozoa, (Diplodinia)
  • rumen protozoa, (Isotricha)
  • rumen protozoa, (Epidinia)
  • rumen fungi, (Neocallimastix)
  • rumen fungi, (Caecomyces)
  • rumen fungi, (Pyromyces)
  • rumen fungi, (Orpinomyces)
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Humans have a long history of exploiting both native and exotic deer species, having hunted them in every geographic region in which they occur. They are often hunted for their meat, hides, antlers, velvet, and other products. As humans began to rely more on agriculture, their dependence on deer species as a food source decreased. However, in areas where climate prohibits wide-scale agriculture, such as in the Arctic, deer species such as caribou are still relied upon for food, clothing, and other resources. In the past, caribou have even been domesticated by nomadic peoples in the high Arctic. Today, many cervid species are hunted for sport rather than necessity. Several species have also been domesticated as harness animals, including caribou and elk. Finally, cervids play an important role in the global ecotourism movement as various species of deer are readily observable throughout much of their native habitat. (Putnam, 1989)

  • Positive Impacts
  • food
  • body parts are source of v