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Rucervus eldiiEld's deer

By Emily Worrel

Geographic Range

Eld's deer (Rucervus eldii) are indigenous to Southeast Asia. They were discovered in the Manipur Valley of India in 1838 by Lieutenant Percy Eld. Three recognized subspecies of R. eldii exist today. They are Rucervus eldii eldii in Manipur, Rucervus eldii thamin, previously in Burma/Myanmar and the Malay Peninsula, and Rucervus eldii siamensis, in Thailand, Annam, and Hainan island. The subspecies Rucervus eldii thamin is now restricted to Burma/Myanmar. Rucervus eldii siamensis is found throughout Hainan island . Some individuals of R. eldii live as far north as 48°N. Eld's deer have also been documented in Cambodia, Laos, and Vietnam. (McCracken, 1996; McShea, et al., 1999; Monfort, et al., 1990; Wildt and Wemmer, 1999; Yan Ling, 1996)

Habitat

The main habitat for Eld's deer is referred to as an indaing forest and is usually dominated by the tree Dipterocarpus tuberculatus. Indaing refers to sandy, flat terrain that floods seasonally. The range of Eld's deer also includes monsoonal forest. Rucervus eldii thamin is found in a variety of habitats, ranging from dry scrub and thorn forest to open deciduous forest. There are three main types of deciduous forests in southeastern Asia: dipterocarp (indaing), dry (thandahat), and mixed (teak). All three of these receive between 100 and 200 cm of rainfall a year. (Aung, et al., 2001; Bronson, 1989; McShea, et al., 1999; McShea, et al., 2001; Prescott, 1987)

The ability of Eld's deer to obtain adequate amounts of nutrients to sustain both the bone growth and body mass of males, and the gestation and lactation needs of females, depends heavily on the types and abundances of food sources in the habitat. Rucervus eldii exhibits seasonal movements that are slightly correlated with crop cycles. They tend to wander farther from crop land during the hot-dry season, mainly because they are moving closer to existing water holes. (McShea, et al., 1999; McShea, et al., 2001; Prescott, 1987)

Physical Description

Adults weigh between 70 and 130 kg. Eld's deer have selenodont teeth, a large body and foregut fermentation type of digestion. (Aung, et al., 2001; McCracken, 1996; McShea, et al., 2001; Prescott, 1987)

Eld's deer, like many other cervids, have a reddish brown to gray colored coat. They are similar in size to white-tailed deer, but differ somewhat in appearance. They have uniquely shaped antlers that are replaced every year. The antlers of Eld's deer are shaped in one continuous curve from the pedicle on the head to the very tip of the antler. There is a lesser branch of the antler that is positioned directly off the pedicel that grows in the direction of the front of the head. (McCracken, 1996; McShea, et al., 2001; Prescott, 1987)

  • Range mass
    70 to 130 kg
    154.19 to 286.34 lb

Reproduction

Rucervus eldii exhibits polygynous mating. (Bronson, 1989; Hosack, et al., 1997; Monfort, et al., 1990)

Rucervus eldii females can begin reproducing at 2 years of age and typically continue to reproduce until they are 10 years of age. They begin estrus in the late winter or early spring. They exhibit a long period of ovarian activity of 225 to 342 days, during which the females average 10 to 17 estrous cycles. Then after they have mated, females enter anestrus. This is just the opposite of estrus, and is a period when they are not sexually receptive. This cycle occurs in the autumn months. Some studies have shown that the presence of males triggers ovarian function in females. (Aung, et al., 2001; Hosack, et al., 1998; McCracken, 1996; Prescott, 1987; Yan Ling, 1996)

The proportion of males to females at birth tends to be a 1:1. The average gestation period for Eld's deer is about 34 weeks or 8 and a half months. Females of the subspecies R. eldii siamensis have been shown to give birth annually for up to 6 consecutive years. Females are fertile for a maximum of 12 to 14 years. Most births of R. e. siamensis occur between October and November (75 percent if 171 reported births). Of all births, 94 percent occurred betweem October 1 to February 28. About 92 percent of births involve single young, while the remaining 8 percent are twins. Most twins are apparently stillborn or die within a few days of birth. (Aung, et al., 2001; Hosack, et al., 1998; Prescott, 1987; Yan Ling, 1996)

The average weight of a newborn from the subspecies R. e. thamin is between 4.7 and 4.8 kg. Newborns of R. e. eldii are slightly larger, averaging between 4.7 and 6 kg. The young are weaned at about 5 months of age. (Aung, et al., 2001; McCracken, 1996; McShea, et al., 2001; Prescott, 1987)

  • Breeding interval
    Eld's deer tend to breed once per year.
  • Breeding season
    Breeding occurs from February to May.
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1
  • Average gestation period
    7.93 months
  • Range weaning age
    4 to 6 months
  • Average age at sexual or reproductive maturity (female)
    2 years

Like most cervids, R. eldii mothers hide their young immediately after birth. Females typically give birth during the cool-dry season when the flood waters have receded and vegetation has begun to grow. This provides the young with shelter and helps to conceal them. (Aung, et al., 2001; McShea, et al., 2001)

After 4 to 5 months, the fawns are weaned. By the end of time of weaning, the climate has changed to the hot-dry season, and the deer tend to migrate. The 4 to 5 month nursing period allows fawns to have sufficient time to increase their mobility, so they are able to travel with the herd. (Aung, et al., 2001; McShea, et al., 2001)

Fawns are primarily raised by their mothers. Males are around, usually watching over the herd, but they do not participate in most of the parental care. (Aung, et al., 2001; McShea, et al., 2001)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • protecting
      • male
      • female

Lifespan/Longevity

The maximum recorded longevity of a R. e. siamensis male in captivity is 14 years and 11 months. Females can live up to 19 years and 7 months in captivity. (Prescott, 1987)

  • Range lifespan
    Status: captivity
    19 (high) years

Behavior

Rucervus eldii is mainly nocturnal and crepuscular. Males tend to be loners throughout most of the year, except in the spring when mating begins. Females tend to remain in close association with their fawns and other female-fawn pairs. Large groups are often formed when males join these groups of females before the breeding season begins. Groups of 1 to 20 animals are common, and usually have a male to female ratio of 1:1.59, and a doe to fawn ration of 1:0.54. Group sizes peak in April and begin to slowly decrease through September. (Aung, et al., 2001; McCracken, 1996)

Rucervus eldii is reported to have both daily and seasonal migrations. These movements are largely influenced by breeding times and differences in availability of food and water in the various seasons. (Aung, et al., 2001; McCracken, 1996)

In captive populations, Eld's deer are known to be very excitable. They often become alarmed at the smallest disturbance and will run around frantically intheir enclosures, sometimes bumping into everything in their path. (Aung, et al., 2001; McCracken, 1996)

  • Range territory size
    3.80 to 14.71 km^2

Home Range

The home range for these animals varies from 3.8 to 14.71 square km.

Communication and Perception

Most cervids have numerous glands on their feet, legs, and faces. These scent glands are used for intraspecific communication. Males often use chemosignaling through urine and feces to inform females that they are in reproductive condition. Not only do cervids utilize chemosignaling, they also use sight and touch. This is mostly commonly displayed before breeding when their antlers are at their largest. Rucervus eldii does not use combat as its primary mode of hierarchy, but it is sometimes necessary to fend off a competing male. (Aung, et al., 2001; Hosack, et al., 1998)

Food Habits

Rucervus eldii is a species known to graze and browse opportunistically on wild fruits and cultivated crops from nearby fields. A few commonly eaten crops are rice, lentils, maize, peas and rape. Rucervus eldii thamin tends to eat the fruits of various woody species such as Emblica officinalis, Terminalia chebula, and Diospyrous burmanica. They also eat forbs and grasses in these areas. (Aung, et al., 2001; McShea, et al., 2001; Monfort, et al., 1990)

Rucervus eldii is closely associated with areas that are seasonally burned. These deer eat the new grasses as they emerge after the burn. (Aung, et al., 2001; McShea, et al., 2001; Monfort, et al., 1990)

Feeding may vary seasonally, not just with food availability, but with reproductive considerations. During rut males, experience a decline in body weight. This is proably due to a decrease in their food intake. (Aung, et al., 2001; McShea, et al., 2001; Monfort, et al., 1990)

All cervids are foregut fermentators. This means that they have four-chambered stomachs, and are able to extract the majority of the nutrients offered by their poor quality food source. (Aung, et al., 2001; McShea, et al., 2001; Monfort, et al., 1990)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit

Predation

One anti-predator adaptation of R. eldii is periodically forming large groups or herds, even though these deer are usually solitary creatures. Large groups decrease the risk of predation, both by increasing the chance that a predator will kill a neighboring animals rather than a lone individual, and by the increased vigilance for predators which can be provided by all members of the group. (Aung, et al., 2001)

The most common predators of R. eldii are tigers, leopards, and dholes. But only the latter two predators still exist in abundant numbers in the present range of this deer. Jackals and occasionally feral dogs also hunt R. eldii. Poaching by humans is a serious problem to Eld's deer populations. (Aung, et al., 2001)

Ecosystem Roles

Rucervus eldii plays an important role in dispersing seeds due to its dependence upon fruit as a food source. This species is probably also important in structuring plant communities as a result of its browsing behavior. (Aung, et al., 2001; McShea, et al., 2001)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Eld's deer are hunted as game animals and are used as a food source. They are prized as a game animal because of their antlers and hides. There have been cases when these deer have been used for "traditional" medicinal products. Oftentimes, Els's deer are poached for this purpose. In addition to these destructive uses, Eld's deer have become a major zoo animal, especially since their populations are decreasing in the wild. (McCracken, 1996; McShea, et al., 1999)

Economic Importance for Humans: Negative

Rucervus eldii is known to feed heavily on the cultivated crops of the local farmers. These deer are a major destroyer of crops, and are considered by locals to be a significant agricultural problem. (Aung, et al., 2001)

  • Negative Impacts
  • crop pest

Conservation Status

All three subspecies of R. eldii have become threatened. Conservation of these deer in tropical regions is difficult because of the fragmentation of their forest home caused by farming. These deer are a targer for poaching, as they can be used for food, trophies, and "traditional" medicinal products. The increase of the human population within the range of this species puts a additional stress upon these animals. There is a lack of funding for protection.

One of the subspecies, R. e. eldii, has become so rare that survival will eventually rely on the practice of gene exchange of the wild and captive organisms by means of assisted reproduction. This type of assisted breeding is being used in Thailand and Burma/Myanmar on the other subspecies as well.

Poaching reduced the R. e. siamensis population from a reported 500 individuals in 1964, to 26 in 1976. Hainan Datian Nature Reserve was established to help R. e. siamensis recover, and the population increased to 151 individuals by 1986. (McCracken, 1996; McShea, et al., 1999; Prescott, 1987; Wildt and Wemmer, 1999; Yan Ling, 1996)

Other Comments

Eld's deer are sometimes refered to as brow-antlered deer. They were previously considered a member of the genus Cervus as Cervus eldi or Cervus eldii. (Prescott, 1987)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Emily Worrel (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

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.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

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.

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

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).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

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.

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

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).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

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.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Aung, M., W. McShea, S. Htung, A. Than, T. Soe. 2001. Ecology and Social Organization of a Tropical Deer (*Cervus eldi thamin*). Journal of Mammalogy, 82(3): 836-847. Accessed (Date Unknown) at http://www.bioone.org/bioone/?request=get-document&issn=0022-2372&volume=082&issue=03&page=0836.

Bronson, F. 1989. Mammalian Reproductive Biology. Chicago, Illinois: The University of Chicago Press.

Hosack, D., K. Miller, R. Marchinton, S. Monfort. 1997. Ovarian Activity in Captive Eld's deer (Cervus eldi thamin). Journal of Mammalogy, 78(2): 669-674.

Hosack, D., K. Miller, R. Marchinton, C. Wemmer, S. Monfort. 1998. Stag Exposure Augments Progestagen Excretion in Eld's deer(*Cervus eldi thamin*). Mammalia, 62: 341-350.

McCracken, K. 1996. At the Zoo: Saving the Skittish Eld's Deer. Zoogoer, 25(3). Accessed (Date Unknown) at http://www.fonz.org/zoogoer/zg1996/eld'sdee.htm.

McShea, W., M. Aung, D. Poszig, C. Wemmer, S. Monfort. 2001. Forage, Habitat Use, and Sexual Segregation by a Tropical Deer (*Cervus eldi thamin*) in a Dipterocarp Forest. Journal of Mammalogy, 82(3): 848-857. Accessed (Date Unknown) at http://www.bioone.org/bioone/?request=get-document&issn=0022-2372&volume=082&issue=03&page=0848.

McShea, W., P. Leimgruber, M. Aung, S. Monfort, C. Wemmer. 1999. Range Collapse of a Tropical Cervid (*Cervus eldi*) and the Extent of Remaining Habitat in Central Myanmar. Animal Conservation, 2(3): 173-183. Accessed (Date Unknown) at http://www.csa.com/htbin/linkabst.cgi?issn=1367-9430&vol=2&firstpage=173.

Monfort, S., C. Wemmer, T. Kepler, M. Bush, J. Brown. 1990. Monitoring Ovarian Function and Pregnancy in the Eld's deer (*Cervus eldi thamin*) by Evaluating Urinary Steroid Metabolite Excretion. Journal of Reproduction & Fertility, 88: 271-281.

Prescott, J. 1987. The Status of the Thailand Brow-Antlered Deer (*Cervus eldi siamensis*) in Captivity. Mammalia, 51(4): 571-577.

Wildt, D., C. Wemmer. 1999. Sex and Wildlife: The Role of Reproductive Science in Conservation. Biodiversity and Conservation, 8(7): 965-976.

Yan Ling, S. 1996. Population Viability Analysis for Two Isolated Populations of Hainan Eld's deer. Conservation Biology, 10(5): 1467-1472.

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