Diversity
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).
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.
- Biogeographic Regions
- nearctic
- palearctic
- oriental
- ethiopian
- neotropical
- australian
- oceanic islands
Habitat
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.
- Habitat Regions
- temperate
- tropical
- polar
- terrestrial
- Terrestrial Biomes
- tundra
- taiga
- desert or dune
- savanna or grassland
- chaparral
- forest
- rainforest
- scrub forest
- mountains
- Other Habitat Features
- urban
- suburban
- agricultural
Systematic and Taxonomic History
As is the case with many families within the order
Artiodactyla
, a well-supported systematic and taxonomic history of
Cervidae
has yet to be established. According to Gilbert et al. (2006), which used mitochondrial
and nuclear DNA to determine the phylogenetic relationship between species,
Cervidae
can be broken down into two subfamilies,
Cervinae
and
Capriolinae
. However, Hernandez-Fernandez and Vrba (2005) provide support for 3 subfamilies,
Hydropotinae
,
Cervinae
, and
Odocoileinae
. Regardless, most recent classification attempts incorporate differences in the gross
morphology of the
metacarpals
. Those species that retain the proximal portion of the lateral metacarpals are grouped
into
Plesiometacarpalia
(
Cervinae
and
Muntiacinae
), and those that retain the distal portion of the lateral metacarpals are grouped
into
Telemetacarpalia
(
Odocoileinae
and
Hydropotinae
). Traditionally,
Cervidae
has consisted of 3 subfamilies:
Capreolinae
(brocket deer, caribou, deer, moose, and relatives),
Cervinae
(elk, muntjacs, and tufted deer), and
Hydropotinae
(water deer). The family
Moschidae
, the musk deer, which are known for their large upper canines, was once a subfamily
of Cervidae but is now considered a separate family.
All extinct and living deer are thought to have evolved during the
Miocene
and early
Pliocene
from a Eurasian ancestor known as protodeer (
Dicroceridae
). The first true cervids appeared about 20 million years ago during the early
Miocene
, which is around the same time cervids began moving from Asia into Europe and North
America. Early cervids began movement into North America via the Berigian Land Bridge
and became relatively common in North America during the early
Pliocene
. Some
Pleistocene
cervids had spectacular antlers. For example, the "Irish elk" Megaloceros, which
was not an elk and was not restricted to Ireland, had large palmate antlers with a
span up to 3.7 m and a weight around 45 kg. In North America, the giant stag moose
had tripalmate antlers that spanned almost 5 feet in width. Another extinct deer with
spectacular antlers was Eucladoceros, a large animal whose antlers were made up of
many of irregularly branched tines. Synapomorphies of extant cervids include
deciduous antlers
, no upper
incisors
, two
lacrimal
orifices on or outside the orbital rim, and an ethmoidal or antorbital
vacuity
that terminates the lacrimal short of nasal articulation.
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
.
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
.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
- sexes shaped differently
- ornamentation
Reproduction
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.
- Mating System
- monogamous
- polygynous
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.
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.
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
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.
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 seasonâs offspring. In many species, females stay
within their motherâs range after maturation, while males are forced to disperse.
In most species, males do not provide any parental care to their offspring.
- Parental Investment
- female parental care
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
protecting
- female
-
provisioning
- post-independence association with parents
Lifespan/Longevity
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.
Behavior
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.
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 âsign-inâ, 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.
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 âhard lookâ, 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 âhard lookâ is successful, he or she will drop and extend their head toward
the subordinate individual, after which a charge may occurs.
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.
- Key Behaviors
- cursorial
- terricolous
- diurnal
- crepuscular
- motile
- migratory
- solitary
- territorial
- social
- dominance hierarchies
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.
- Other Communication Modes
- pheromones
- scent marks
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.
- Foraging Behavior
- stores or caches food
Predation
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.
- 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.
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.
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.
- Ecosystem Impact
- disperses seeds
- 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 )
- parasitic flatworms, ( Nematoda )
- parasitic flatworms, ( Trematoda )
- parasitic roundworms, ( Cestoda )
- ticks, ( Ixodoidea )
- flies, ( Diptera )
- mosquitoes, ( Culicidae )
- fleas, ( Siphonaptera )
- keds, ( Hippoboscidae )
- mites, ( Psoroptes and Sarcoptes )
- lice, ( Phthiraptera )
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.
- Positive Impacts
- food
- body parts are source of valuable material
- ecotourism
Economic Importance for Humans: Negative
Many species of cervid are viewed as agricultural pests, especially in areas where
they have become overpopulated due to habitat alterations and lack of natural predators.
The effects of deer on crops can be devastating. Most cervid species are forest dwellers
and as a result, they can cause damage to timber by browsing, bark-stripping, and
velvet cleaning. In addition, deer-vehicle collisions result in significant harm
to the health and personal property of those involved. Many cervids carry diseases
that can be transmitted to domestic livestock and certain species, including
white-tailed deer
,
elk
, and
Javan rusa
, have been introduced outside of their geographic ranges, causing significant harm
to native plant and animal communities.
- Negative Impacts
- crop pest
- causes or carries domestic animal disease
Conservation Status
The IUCN's Red List of Threatened Species lists 55 species of
Cervidae
, 2 of which are listed as extinct and 1 is considered critically endangered. Of the
remaining 52 species, 8 are endangered, 16 are vulnerable, and 17 are listed as "least
concern". The remaining 10 species are listed as "data deficient". Many more local
deer population are on the cusp of extirpation, which could lead to inbreeding in
adjacent populations. According to the IUCN, major threats of extinction for cervids
includes over exploitation due to hunting, habitat loss (e.g., logging, conversion
to agriculture, and landscape development), and resource competition with domestic
and invasive animals. In addition, climate change has begun to contract species ranges
and forced some species of cervid to move poleward. For example,
moose
, which are an important ecological component of the boreal ecosystem, are notoriously
heat intolerant and are at the southern edge of their circumpolar distribution in
the north central United States. Since the mid to late 1980's, demographic studies
of this species have revealed sharp population declines at its southernmost distribution
in response to increasing temperatures. In addition, climate change has allowed more
southerly species to move poleward, which increases competition and disease transmission
at range interfaces of various species (e.g.,
white-tailed deer
and
moose
). Finally, cervids are an important food source for a number of different carnivores.
As cervid populations decline, so too will those animals that depend on them.
CITES
(the Convention on International Trade in Endangered Species of Wild Fauna and Flora)
lists 25 species of cervid under appendix I.
Additional Links
Contributors
Katie Holmes (author), University of Michigan-Ann Arbor, Jessica Jenkins (author), University of Michigan-Ann Arbor, Prashanth Mahalin (author), University of Michigan-Ann Arbor, John Berini (author, editor), Animal Diversity Web Staff, Phil Myers (editor), University of Michigan-Ann Arbor.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- oceanic islands
-
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- polar
-
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
- terrestrial
-
Living on the ground.
- tundra
-
A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
- taiga
-
Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- chaparral
-
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- rainforest
-
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- bog
-
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- agricultural
-
living in landscapes dominated by human agriculture.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual ornamentation
-
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
- monogamous
-
Having one mate at a time.
- polygynous
-
having more than one female as a mate at one time
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- female parental care
-
parental care is carried out by females
- diurnal
-
- active during the day, 2. lasting for one day.
- crepuscular
-
active at dawn and dusk
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- solitary
-
lives alone
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- social
-
associates with others of its species; forms social groups.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- food
-
A substance that provides both nutrients and energy to a living thing.
- ecotourism
-
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
- causes or carries domestic animal disease
-
either directly causes, or indirectly transmits, a disease to a domestic animal
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
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