Characteristic deer, subspecies, reproduction, feeding

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Philip Kelley
Characteristic deer, subspecies, reproduction, feeding

The deer or deer are placental mammals that make up the family Cervidae. The main characteristic of this clade are the antlers; These bony structures are present in all deer except the Chinese water deer (Hydropotes inermis inermis).

Another characteristic of antlers is that only males have them, less in the case of species of the genus Rangifer, where both sexes have antlers. These grow from pedicels, located on the frontal bone. In addition, they are covered with a special fabric called velvet, which is highly vascularized and innervated..

Deer. Source: USDA photo by Scott Bauer [Public domain]

The Cervidae family is very extensive, with a total of twenty-three genera and forty-seven species, which are grouped into three large subfamilies: Hydropotinae, and Capreolinae.

Article index

  • 1 Evolution
    • 1.1 Eocene Epoch
    • 1.2 Oligocene Epoch
    • 1.3 Miocene Epoch
    • 1.4 Pliocene Epoch
    • 1.5 Epoch of the Pleistocene
  • 2 Features
    • 2.1 - Size
    • 2.2 - Teeth
    • 2.3 - Fur
    • 2.4 - Antlers
  • 3 Taxonomy and subspecies
  • 4 Habitat and distribution
    • 4.1 - Distribution
    • 4.2 - Habitat
  • 5 Conservation status
    • 5.1 - Threats and actions
  • 6 Playback
    • 6.1 Seasonal mating
    • 6.2 Seasonality in the male
    • 6.3 Seasonality in the female
  • 7 Food
    • 7.1 Factors
  • 8 Behavior
  • 9 References 

Evolution

Pampas deer (Ozotoceros bezoarticus) Sources: Scott Presnell / Public domain

According to research, the ancestors of the deer lived in the Eocene and lacked antlers, but had fangs. Experts suggest that the evolution of the Cervidae family occurred in stages and lasted for around 30 million years..

Eocene epoch

Ruminants, ancestors of the Cervidae, are believed to have evolved from the Diacodexis, who lived between 50 and 55 million years ago in North America and Eurasia.

Its body was around 50 centimeters long and it had a long tail. On each limb it had five fingers, with the peculiarity that the third and fourth were elongated..

Oligocene epoch

In the second half of the Oligocene, the Eumeryx European and the Leptomeryx North American. The latter had the appearance of bovids, but their teeth were similar to that of modern deer.

Miocene epoch

Fossil records suggest that the first members of the superfamily Cervidae lived in the Miocene, in Eurasia. According to research, the first deer with antlers are the Dicrocerus, Heteroprox Y Euprox.

In this period, the Tethys Ocean disappeared, giving way to vast grasslands. This provided the deer with abundant highly nutritious vegetation, allowing it to flourish and colonize other areas..

Pliocene epoch

Bretzia was one of the three known genres (Bretzia, Eocoileus, Odocoileus) as one of the evolutionary radiation of cervids that occurred in the Pliocene. This occurred after the initial immigration from Asia to North America, during the Miocene-Pliocene boundary..

Bretzia was similar in size to mule deer (O. hemionus), but had differences regarding the postcranial skeleton, teeth, and antler and skull morphology,

As for the pedicles of the antlers, they are found further apart than in most cervids. In this genus, the antlers have a webbed structure. Deer arrived in South America in the late Pliocene, as part of the Great American Exchange, through the Isthmus of Panama..

Pleistocene epoch

Large antler deer evolved in the early Pleistocene. In this sense, the genus Eucladoceros were comparable, in size, to modern elk. One of the genera that included large species was Megaloceros, which lived in Eurasia in the late Pleistocene.

Characteristics

Chinese water deer (Hydropotes inermis inermis). Source: William Warby / Public domain

In general, members of the Cervidae family have a compact body and a short tail. Its limbs are long and muscular, suitable for the rocky and woody terrain where it inhabits.

In relation to the skull, deer are characterized by lacking a sagittal crest and by having a postorbital bar. The vast majority have a facial gland, located near the eye.

It contains a substance called pheromone, which can be used to mark territory. Males secrete this strong scent when irritated or excited..

These mammals have excellent night vision. This is because they have a tapetum lucidum, which is a membranous layer located between the optic nerve and the retina. Its function is similar to that of a mirror, since it reflects the light rays that hit it..

Thus, the available luminosity increases so that the photoreceptors can better capture the environment. In this way, vision in low-light conditions, such as at night in forests, is significantly improved..

- Size

Deer exhibit a wide variation in their physical dimensions. Also, males are generally larger than females..

The smallest deer is the southern pudu (Puda Puda), reaching a height of 36 to 41 centimeters and a weight that ranges from 7 to 10 kilograms. The largest species is the elk (Moose moose), which could measure up to 2.6 meters tall and weigh up to 820 kilograms.

- Teeth

The vast majority of deer have 32 teeth. However, reindeer have 34 teeth. The characteristics of the upper canines present variations, depending on the species.

Thus, in the Chinese water deer, muntjac deer, and tufted deer, these teeth are elongated, forming sharp fangs. Conversely, other cervids lack canines or are vestigial.

As for the cheek teeth, they have growing enamel ridges, which allow grinding the plant material they consume. Cervids do not have upper incisors, but they do have a hard palate.

The front part of the upper jaw is covered by a hardened tissue, against which the canines and lower incisors are occluded.

- Fur

The fur has a coloration that varies between brown and red. However, the tufted deer has chocolate brown hair and the elk has grayish hair. Also, some species have white spots, such as fallow deer, chital and sika.

Deer have two molts a year. Thus, the red and fine fur that the red deer has during the summer is gradually replaced until in autumn it has a dense and grayish-brown color..

- Antlers

All species of deer have antlers, with the exception of the Chinese water deer (Hydropotes inermis inermis). Also, all males have antlers, except the reindeer..

These structures grow from pedicels, which are bony supports located on the sides of the frontal bone. The antlers initially emerge as soft tissues, known as velvet antlers..

Then, these are progressively hardened, due to a process of mineralization and blockage of the blood vessels. Thus, they become hard bone antlers.

The velvet, or skin covering, is rich in blood vessels and nerve endings. When the antlers reach their maximum size, the velvet dies and is shed as the animal rubs them against the vegetation..

The sutures responsible for holding the antlers to the deer head are decalcified annually. This causes the antlers to fall off, usually in late fall or early winter..

Before long, they begin to grow again. In this stage, the expanding bone is covered with a thin layer of skin, which performs a protective function..

Shapes

Because growth is not limited to the base, as is the case with horns, antlers have growth patterns specific to each species. Thus, they can vary from having a simple spike shape, as in the case of muntjacs, to being large and branched structures, as occurs in elk..

Regarding this aspect, some antlers are webbed, while those of the pudu are simple quills. Others have a series of teeth, emerging upward, from a curved main beam.

In relation to size, the common fallow deer (Range range) and reindeer have the heaviest and largest antlers, while the tufted deer have the smallest. As for the lightest, in relation to their body mass, the pudu has them.

Utility

In deer, antlers are one of the most prominent male secondary sexual characteristics. Among its main functions is to guarantee reproductive success and to be a combat element between males..

The antlers are correlated with the hierarchy that the deer occupies within the group. In this sense, the heavier they are, the higher the position of the animal within the group. Also, experts point out that a male with large antlers tends to be more dominant and aggressive than the rest of the males..

On the other hand, the moose that inhabit Yellowstone National Park, use antlers to protect themselves against the attack of wolves.

Taxonomy and subspecies

Red deer. Source: Tim Felce (Airwolfhound) / Public domain

-Animal Kingdom.

-Subkingdom: Bilateria

-Phylum: Chordate.

-Subfilum: Vertebrate.

-Infrafilum: Gnathostomata.

-Superclass: Tetrapoda.

-Class: Mammal.

-Subclass: Theria.

-Infraclass: Eutheria.

-Order: Artiodactyla.

-Family: Cervidae.

-Subfamily: Capreolinae.

Genus: Moose, Rangifer, Blastocerus, Pudu, Capreolus, Ozotoceros, Hippocamelus, Odocoileus, Mazama.

-Subfamily: Cervinae.

Genres: Cervus, Rusa, Dama, Rucervus, Elaphodus, Przewalskium, Elaphurus,

Muntiacus.

-Subfamily: Hydropotinae.

Genus: Hydropotes.

Habitat and distribution

Pudú (Pudu mephistolephis). Source: Eider Joselito Chaves / Public domain

- Distribution

Cervids are widely distributed on all continents except Antarctica, Australia, and much of Africa, where only the Barbary deer subspecies exists (Cervus elaphus barbarus), north of Tunisia and Algeria.

North America

The largest concentration of deer in North America is in Canada, the Columbia Mountains, and the Rocky Mountains. There are a number of national parks in the British Columbia region, including Mount Revelstoke National Park, Yoho National Park, Glacier National Park, and Kootenay National Park..

In Montana and Alberta, deer inhabit Banff National Park, Glacier National Park, and Jasper National Park.

Eurasia

The Eurasian continent, including the Indian subcontinent, has the largest deer populations in the world. Some species that have traditionally been associated with Europe, such as the red deer, fallow deer and corozos, currently also live in Asia Minor, in Iran and in the Caucasus mountains..

In Europe, cervids are found in the Scottish Highlands, the wetlands between Hungary, Austria and the Czech Republic, and in the Austrian Alps, among others..

In addition, they are found in some national reserves, such as the Doñana National Park (Spain), the Białowieża National Park (Poland), the Veluwe in the Netherlands and the Ardennes (Belgium).

In Asia, deer are distributed in coniferous mountain forests, mixed deciduous forests and the taiga, which borders Manchuria (China), North Korea and Ussuri (Russia). The Asian caribou live in the northern fringes of these regions, along the entire Russian-Chinese border..

- Habitat

Cervids inhabit diverse ecosystems, ranging from the tundra of Greenland and Canada to the rainforests of India. Thus, they inhabit deciduous forests, grasslands, wetlands, arid scrub and alpine areas..

Some species prefer ecotones, in transitional areas between shrubs and forests and between savannas and grasslands. Other cervids live almost exclusively in grasslands, mountains, humid savannas, swamps, and in riparian corridors surrounded by deserts..

The small species of deer and pudúes of South and Central America, as well as the muntjacs of Asia, generally inhabit dense forests, avoiding open spaces..

Likewise, various deer are circumpolarly distributed, both in Eurasia and North America. For example, the caribou lives in the taiga and arctic tundra.

In the habitats of the mountainous slopes, they live both in forests and in subalpine dry forests. The forest caribou is found in a more restricted range, between the subalpine meadows and the alpine tundras.

As for the elk, they range in the lowlands of the river valley. White-tailed deer have expanded their range to the bottoms of river valleys and foothills of the Rocky Mountains in Canada..

State of conservation

Moose (Alces alces). Source: Donna Dewhurst / Public domain

Within the extensive family Cervidae there are numerous species in danger of extinction, because their populations are threatened by various factors, thus causing their decline..

A total of 56 deer have been listed by the IUCN as at risk of extinction. Among these, one is extinct, the Rucervus schomburgki and another, the Elaphurus davidianus, no longer lives in wild conditions.

Within the group of least concern, 3 are slightly threatened, 16 are vulnerable, 7 are in danger and 2 are in a critical state of extinction. Within the group, 10 cervids do not have enough data for their evaluation.

- Threats and actions

The main threats to deer include their hunting and competition with other animals for food resources. Another factor that affects these mammals is the loss of their habitat, due to the felling of trees and the use of land for agriculture..

Likewise, climate change causes some species to leave their home ranges and move towards the poles. An example of this is the moose, located in the north central United States..

A demographic study carried out in the 1980s reveals a decrease in its southern population, in response to the increase in temperature in that region.

The various threatened species are protected in nature reserves and national parks. In addition, 25 cervids in danger of extinction are part of appendix I of CITES.

Reproduction

Deer puberty occurs around 16 months of age and after this stage, they exhibit seasonal polyester. As for the estrous cycle, it can vary between 17 and 22 days, depending on the species.

This can continue to appear cyclically for up to six months, in the event that the female has not been fertilized. The vast majority of deer are polygamous, however, some species are monogamous, such as the European roe deer..

In some species, males may mate with females whose territories are within their own. Also, these could move between herds, in search of females in heat..

For their part, the females form small groups, called harems, which are protected by the males. These exercise their dominance over the harem, challenging rival males.

Courtship behavior in cervids is characterized by the closeness between the pair, with licking and sniffing of the ano-genital area. Also, the male tends to chase the female and be aggressive towards other males. The length of gestation varies according to the species, however, it has an average of 7 months.

Seasonal mating

Members of the Cervidae family are seasonal breeders. Variations related to rainfall, temperature and day length influence the mating season.

In those climates where the changes in the seasons are extreme, the length of the day is used to time the mating period..

Experts point out that deer respond reproductively better on short days than on long days. This means that estrous behaviors begin to show in late September and October and not during the summer season..

Seasonality in the male

Mating is controlled by melatonin levels. This is a modified hormone, which is released by the pineal gland. In seasons where there are fewer hours of light per day, testosterone values ​​increase.

This could influence the volume and pH of seminal fluid, as well as the motility and concentration of the sperm. Due to this, in the period when the male is more sexually aroused, the quality of the semen is much higher..

Seasonality in the female

Heat in females is triggered by the decrease in the photoperiod. In this sense, the pineal gland produces melatonin, in response to the low luminosity of the environment.

Seasonal changes in fertility are associated with the secretion of luteinizing hormone-releasing hormone (LHRH) from the hypothalamus. In turn, this hormone influences the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary.

Feeding

Deer are herbivorous animals that feed primarily on leaves. These select the most digestible parts of the plant, such as young leaves, fresh herbs, fruits, flowers, lichens and fresh herbs..

This is why they are considered concentrated selectors, since they have a tendency to choose the most nutritious parts of plants. However, some species are classified as intermediate.

This feeding behavior is contrary to that of cattle and sheep, who consume large amounts of low-quality fibrous feed..

The dietary requirement of cervids includes a large amount of minerals, such as phosphate and calcium, which contribute to antler growth. This is why some species, such as the red deer that live on the island of Rum, do not only eat vegetables..

Within their diet they usually consume the offspring of some seabirds and their eggs. Specialists point out that this may be due to the mammal's need to recover mineral elements that plants do not contain..

Factors

Deer feeding is mixed, between browsing and grazing. In addition, it depends on the seasons and the habitat where it is found. Thus, during winter and spring, their diet is made up of up to 75% herbaceous. In autumn and summer, increase the consumption of fruits and woody plants.

Furthermore, in cervids, food intake is influenced by the nutritional value of the forage, the photoperiod and the stage of the reproductive cycle.

Likewise, the body condition also undergoes variations related to the changes in the seasons. In late summer, the body of deer stores a large proportion of fat. This will be used by the males during their autumn routine.

As for females, they use fat stores gradually in winter and early spring. This allows them to maintain adequate body condition in the first two trimesters of pregnancy, when food resources are limited in the environment..

On the other hand, the reduction of appetite suffered by deer in winter and autumn helps to avoid the energy expenditure caused by the unproductive search for food sources at those times of the year..

Behaviour

Cervids are generally classified as twilight animals, although some species are usually active for much of the day. These animals tend to become more aggressive in situations of food shortage and during the mating season..

Aggressive males, larger in size and with larger horns, tend to dominate the rest of the males. This guarantees them access to the females in heat during the breeding season. In the fighting between males and males, they can use their antlers.

Also, they could walk around each other, surrounding each other, while vocalizing a high-pitched moan or low growl. Deer often lift body hair by contracting the retractor pili muscle, making it appear larger..

In the mating season, males use their forelimbs to scrape the ground, thus announcing their presence and willingness to mate. They may occasionally urinate or deposit their stool on the scraped area.

Regarding the social organization of cervids, it is variable and could be influenced by the season. Although the vast majority of species form small groups, for food they could be grouped in large herds. Once the objective is achieved, they disperse.

References

  1. ITIS (2019). Cervidae. Recovered from itis.gov.
  2. Holmes, K .; J. Jenkins; P. Mahalin, J. Berini (2011). Animal Diversity. Recovered from animaldiversity.org.
  3. Alina Bradford (2017). Facts About Deer. LiceScience. Recovered from livescience.com.
  4. Stefany Gomez (2018). Cervidae: deer, elk, and moose. Recovered from cvm.msu.edu.
  5. Jéssica Morales Piñeyrúa (2010). Copulation behavior in the field deer (Ozotoceros bezoarticus, LINNAEUS 1758). Recovered from colibri.udelar.edu.uy.
  6. Bunnell, F.L. (1987). Reproductive tactics of Cervidae and their relationships to habitat. Biology and Management of the Recovered from researchgate.net.
  7. Eric Paul Gustafson (2019). An early pliocene north american deer: bretzia pseudalces, its osteology, biology, and place in cervid history. Recovered from oregondigital.org.

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