An Ultimate Ungulate Fact SheetReturn to Artiodactyla

Kingdom: Animalia
  Phylum: Chordata
    Class: Mammalia
      Order: Artiodactyla
        Family: Cervidae
          Subfamily: Capreolinae
            Genus: Blastocerus

Blastocerus dichotomus

      Marsh deer


Blastocerus dichotomus [Illiger, 1815].  
Citation: Abh. Phys. Klasse K.-Preuss. Akad. Wiss., 1804-1811:117 [1815].
Type locality: Paraguay, Lake Ypoa, south of Asuncion.

General Characteristics

Body Length: 180-195 cm / 6-6.5 ft.
Shoulder Height: 110-120 cm / 3.6-4 ft.
Tail Length: 10-15 cm / 4-6 in.
Weight: 70-110 kg / 154-242 lb.

The slightly shaggy coat is primarily reddish brown or chestnut in colour, with the undersides, especially the lower surface of the neck, being lighter.  The lower legs are black in colour.  Unlike many deer species, young marsh deer are born without spots.  There is a faint white eye ring, and the muzzle and lips are conspicuously black.  The ears are large and lined with fluffy white hair.  The upper surface of the tail is the same colour as the back, while the bushy underside is dark brown or black.  Like other ungulates adapted to a boggy habitat, the dewclaws of the marsh deer are well developed and the widely-splayed hooves are very long, growing 7-8 cm / 2.8-3.2 inches in length.  Males bear a pair of large, dark yellow antlers about 60 cm / 24 inches in length, with four or five tines each.  The heavy antlers, each weighing 1.65-2.5 kg / 3.6-5.5 lb, are shed irregularly, and a grown set may be retained for up to 21 months.

Ontogeny and Reproduction

Gestation Period: 260 days.
Young per Birth: 1
Weaning: About 5 months.
Sexual Maturity: At 1 year.

Immediately after parturition the female comes back into heat, and hence may be pregnant throughout her breeding years.  Fawns may associate with their mother for over a year after birth.

Ecology and Behavior

Remaining hidden during the day, marsh deer emege at dusk to graze in flooded clearings, retiring again in the early morning.  As its name and habitat preference infer, the marsh deer frequently enters water.  However, it is primarily a wader, preferring areas where the water is less than 60 cm / 2 feet deep.  Excessive flooding causes these deer to retire to higher ground, where they often come into contact with domestic cattle, which carry several diseases which are fatal to this species.  The hindquarters are well developed - an excellent adaptation for jumping (the fastest way to move in waist-deep water).  Males do not spar for breeding privileges, which renders the antlers as primarily ornamental objects.  Population densities range from one deer per 3.8-42.0 square kilometers.

Family group: Solitary, or in groups of less than 6 animals, generally and adult male, a few females, and their young.
Diet: Grasses, reeds, aquatic plants.
Main Predators: Jaguar, anaconda, domestic dogs.


Floodplains and and moist forests in central South America.

Range Map (Redrawn from Whitehead, 1993)

Conservation Status

The marsh deer is classified as vulnerable by the IUCN (1996).


Sometimes called the swamp deer, care must be taken to differentiate between this species and the barasingha (Cervus duvaucelii).  Fortunately for this species, the meat of the marsh deer is said to be unpalatable.  Blastos (Greek) a bud or shoot; keras (Greek) the horn of an animal.  Dikhe (Greek) in two ways; tome (Greek) cutting, sharp: a reference to the doubly forked antlers.

Literature Cited

Eisenberg, J. F., and K. H. Redford.  Mammals of the Neotropics.  Chicago: The University of Chicago Press, 1999.

Geist, V.  1990.  Pampas and swamp deer (Genera Ozotoceros and Blastocerus).  In Grzimek's Encyclopedia of Mammals.  Edited by S. P. Parker.  New York: McGraw-Hill.  Volume 5, pp. 218-219.

Whitehead, K. G.  1993.  The Whitehead Encyclopedia of Deer.  Stillwater, MN: Voyageur Press, Inc.

Wilson, D. E., and D. M. Reeder [editors]. 1993. Mammal Species of the World (Second Edition). Washington: Smithsonian Institution Press.  Available online at

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© Brent Huffman,
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