The Marsh Deer (Blastocerus dichotomus)
Description:
The marsh deer is an animal that lives in the wet marshy areas of South America. The
hide can vary in color from a bright chestnut in the summer to a brown red during the
winter months. Along with these colors the marsh deer also has black and white in
various areas such as the tail and the underside of the legs. The hair on marsh deer is
quite long and very tangled, it is like this all over the deer including the white hairs in the
deer’s ears. Males grow antlers that develop and increase in size, as they get older.
Adult males will have four tines on each side. Usually the older the animals have more
tines and can be asymmetrical. The body size of the marsh deer is similar to the large
Wisconsin northern whitetail deer, they can range from 176lbs or 80kg to 275lb or
125kgs (Pinder 1991).
Distribution:
The marsh deer is a South American species. The range of the marsh deer is shrinking
considerably, now it is only found in these 6 major countries these include Paraguay,
Peru, Uruguay, Bolivia, Brazil, and Argentina (Walfrido 2001). Marsh deer are mostly
found in floodplains of large rivers, some of these include the Paraguay, Guapore,
Parana, and the Araguaia river systems. The largest population of marsh deer is located
in the Pantanal. This huge lowland or marshland is located in the northeastern part of
Paraguay, however the majority of it lays in Brazil and some in Bolivia (Mauro 1998).
The deer’s range shrinks and expands as the dry and wet seasons alter water and in turn
alter the marsh deer’s location (De-Salis 2001).
Ontogeny and Reproduction:
The marsh deer can be found all alone which it the common occurrence or up to groups
of five. During the peak mating periods, which are the months of October and
November, the breeding usually occurs. The gestation period of the marsh deer is 271
days. Most fawns are born from May to September however they are not restricted to
this and sometimes fawns can be seen at any time of the year. The fawns are born with
no spots they have the same mature colors as the adults (Pinder 1991).
Ecology and Behavior:
The marsh deer lives in the flood plain areas that are usually marshy and flooded often.
They stay out of forested areas and prefer the standing water areas of the marsh. They
feed mostly on semi-aquatic plant species, when this food is short or hard to find they
will feed on the leaves of vines and shrubs (Pinder 1991). Some plant species that the
deer have been observed eating are “Aeschynomene sensitiva (Leguminosae),
Discolobium pulchellum (Leguminosae) and Rhabdadenia pohlii (Apocynaceae)”
(Walfrido 2001).
The marsh deer is most active during the night hours however some are seen
during the day, but usually bedded or ruminating. The deer come out around dusk and
are active all hours of the night and early morning. This is when they will feed on marsh
plants. They prefer wading in water around two feet and less. When extreme flooding
occurs the marsh deer takes to higher ground. The marsh deer have an excellent ability to
use there hind legs to jump with power, this helps the deer to move fast in deep water.
The antlers on the marsh deer are just for eye appeal, these deer don’t fight for breading
privileges (Brent Huffman 2004). Antlers are not shed at the same time of the year and it
can vary with the individual. Some males carry there antlers for almost two years before
shedding them (Epps 2000).
Remarks:
There is not a lot known about this particular deer species. The populations are
decreasing due to poaching, disease and also from habitat loss. They are very susceptible
to catching diseases from the cattle that are farmed in there areas. When high flooding
occurs the marsh deer are forced to higher ground and in closer contact with these cattle
(Pinder 1991).
Literature Cited:
1. De-Salis,-Suzana-Maria.,Pereira-da-Silva,-Marta., De-Miranda, Mourao, Guilherme.
2001. Marsh deer (Blastocerus dichotomus) distribution as a function of floods in
Pantanal Wetland, Brazil. Studies-on-Neotropical-Fauna-and-Environment. 2001;
36(1): 9-13.
2. Walfrido M. Tomas, Salis,-Suzana-M.,. Diet of the marsh deer
(Blastocerus dichotomus) in the Pantanal wetland, Barzil. Studies-onNeotropical-Fauna-and-Environment. 2001; 35(3): 165-172.
3. Epps, Clinton. 2000. “Blastocerus dichotomus”, Animal Diversity Web. Accessed
September 29,2004. <http://animaldiversity.ummz.umich.edu/site/accounts/
information/Blastocerus_dichotomus.html>
4. Pinder, L., A. Grosse.1991. Blastocerus dichotomus. Mammalian Species, 380: 1-4.
5. Huffman, Brent. The Ultimate Ungulate Fact Sheet. Blastocerus dichotomus.
10-19-04. 2004 <Http://www.ultimateungulate.com/Artiodactyla/Blastocerus
_dichotomus.html>
6. Mauro, R.A.;Mourao, G.M., Coutinho, M.E.,Silva, M.P. & Megnusson, W.E..
Abundance and Distribution of Marsh Deer Blastocerus dichotomus In The
Pantanal, Brazil. Vol. 5. pp13-20, 1998.
Reference written by Ben Nelson, Biology 378 student. Edited by Christopher Yahnke.
Page last updated.