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Lontra longicaudisneotropical river otter

By Kathleen Berry

Geographic Range

Lontra longicaudis is present from Northwestern Mexico, south into South America; it is the most common otter in Mexico and has the widest distribution of the three S. American Lontra species.

The range extends into Uruguay, Paraguay, and across northern Argentina. (Lariviere, 1999)

Habitat

Lontra longicaudis generally shelters in a self-excavated burrow near permanent lakes or streams. They depend on a water environment with plenty of riparian vegetation (Nowak 1999).

One study looked at the use of shelters by the Neotropical river otter in Brazil, along the Betari River, between August 1993 and December 1994. There were several different types of shelters frequented by the otters. These shelter types include: a cavity among stones, cavity under tree roots, limestone dissolution cavity, cavity in a rocky wall, space among vegetation, and excavated burrows. The most common type of shelter used by the otters in this study was the cavities among stones (35.2%).This type of shelter is not deep and has a broad entrance. It is actually a space among pebbles and rock along the river bank (Pardini and Trajano 1999).

The Neotropical river otter is also known to use caves as shelters, which other otters tend not to do. A few of the caves were used to rear young. It was suggested the caves were generally far from the main river and were protected sites. These are features common to other otter rearing dens (Pardini and Trajano 1999).

It was also noted that otters' scent marking behavior is concentrated in those areas of the home ranges which they frequent more than others, in their activity centers. Along the Betari River, Lontra longicaudis did not concentrate its scent marks around shelters. Apparently, this means the shelters are not necessarily centers of activity for the otters in riverine habitats (Pardini and Trajano 1999).

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Lontra longicauda generally weighs less than 12 kilograms. Sexually dimorphic in size, the males average 20-25% larger than the females (Lariviere 1999).

L. longicauda is also known as the Neotropical otter. Head and body length can be 360-660 mm, length of the tail 370-840 mm, length of the hind foot 94-144 mm, and length of the ear ranges from 18-22 mm (Lariviere 1999).

Some average measurements of the long, flat skull include: basal length about 96.4 mm, zygomatic breadth 68.1mm, and postorbital breadth averaging 17.9 mm. The head is small and flat, bearing small eyes and short, round ears. The otter's neck is thicker than the head (Lariviere 1999).

The Neotropical otter has short, dense, sleek pelage, which is described as a lustrous grayish-brown. This otter is slightly paler ventrally, especially on the throat. On its face, the upper lip, mandible, and tip of the muzzle are silvery white to yellowish. The muzzle appears broad. The tail is long, wide, and quite thick at the base. It tapers to a point. The legs are short and stout, and the toes on all the otter's feet are webbed (Lariviere 1999).

Females have four nipples on the abdomen. The males have a well-developed baculum with a total length of around 72 mm. It has a small ventral groove, shallow at the proximal end and running deeper at the distal end (Lariviere 1999). (Lariviere, 1999)

  • Sexual Dimorphism
  • male larger
  • Range mass
    5 to 15 kg
    11.01 to 33.04 lb
  • Range length
    360 to 660 mm
    14.17 to 25.98 in

Reproduction

Depending on the otters' locality, it breeds mostly in the spring, but may also breed throughout the year. Following a gestation period of 56 days, one to five young are born, but generally, there is only two or three in the litter. There is an indication of facultative delayed implantation, but it is not known how long the delay may be (Lariviere 1999).

Young are born blind, opening their eyes after 44 days. They are born fully furred. The young leave the den or nest when about 52 days old and spend most of the day playing near the natal den. At about 74 days post birth they start their aquatic activity with their mothers. Males do not provide any parental care. (Lariviere, 1999)

  • Breeding interval
    Neotropical otters breed once per year.
  • Breeding season
    Some populations breed only in the spring, others throughout the year
  • Range number of offspring
    1 to 5
  • Average number of offspring
    2-3
  • Average number of offspring
    2.5
    AnAge
  • Average gestation period
    56 days
  • Average gestation period
    57 days
    AnAge

Behavior

The neotropical otter is a solitary animal. A male will only stay with the female for one day in the breeding season. Females have total care of the young (Lariviere 1999).

One way these otters communicate is by scent marking. They deposit feces in conspicuous areas such as logs, root systems, rocks, sand bars, and planks under bridges. It is suggested they prefer sites which are solid, high, dry, and near deep water, but they will spraint on frequently flooded surfaces if the former is not available. It is thought that sprainting may function for advertisement and for the coordination of sexual activity (Lariviere 1999).

Communication can also occur when the otter emits a variety of whistles, hums, and screeches. Otters approaching observers in Argentina uttered a loud "hahh" which researchers felt was an alarm call (Lariviere 1999).

No information was found regarding play behavior, how much time this species spends in the water, or how it spends the day other than foraging. These animals have the form, fur and buoyancy needed to spend a great deal of time in the water.

They move with a humping gallop keeping their head and tail low, the back humped high (Lariviere 1999). Given their choice of shelters so close to the water it can be expected the Neotropical river otter spends at least part of the day swimming and playing as other otters do.

Communication and Perception

Food Habits

The neotropical otter feeds mainly on fish, crustaceans and molluscs. It is also an opportunistic feeder, eating insects, reptiles, birds, and small mammals. It has been suggested that foraging occurs all day, happening more commonly in the middle or late afternoon. Nocturnal activity is rare, but some neotropical otters have become completely nocturnal when their normal activities are disturbed by humans (Lariviere 1999).

L.longicaudis is a graceful swimmer and diver. They are always found in or near the water. Their foraging dives can last from 20-30 seconds. The otter consumes small prey while in the water but will take larger prey to the shore to eat it (Lariviere 1999).

Two separate studies were conduted regarding the feeding habits of the neotropical river otter and the results are described here. One study was conducted at a dam in the "Duas Bocas" Biological Reserve in Brazil, between July 1986 to July 1987. This reserve is covered mainly by the Atlantic Rain Forest. The study was based on otter fecal (spraints) analysis and compared with known species found in the dam. The material collected was resistant to gastric juice, including fish bones, rays, jaws, and teeth of a number of animals, plus crab and insect exoskeletons (Helder and DeAndrade 1997).

The most important food item was fish, which in this study was present in 97.2% of the samples. Also observed were crustaceans, amphibians, mammals, insects, and birds. Crustaceans were the second most commonly encountered food item. The authors indicated that greater abundance and easier capture of fish make them the main food item for the otters (Helder and DeAndrade 1997).

Between August 1993 and September 1994 another study was carried out in an Atlantic forest stream in south-eastern Brazil, the Betari River. Likewise, the author studied undigested remains in the otter's scat. In 93% of the samples fish was found. Aquatic insects and crustaceans were also found frequently (78.9%). The conclusion of this study was that otters are sometimes influenced in their selection of food items according to the availability of prey and its ability to escape (Pardini 1998).

These studies characterize L. longicaudis as a piscivorous mustelid that engages in opportunistic feeding.

Predation

There are a number of animals which prey on Neotropical river otters including anacondas, jaguars, caimans, dogs and birds of prey. Humans kill them for meat, fur, or incidentally in fishing operations, as these otters frequently get caught and drown in nets (Lariviere 1999).

Economic Importance for Humans: Positive

In the past, the Neotropical otter was heavily hunted for its fur. During 1950-1970 this resulted in this otter becoming extinct over parts of its former range. The retail price of one L. longicaudis pelt around 1990, was U.S. $25-90 (Lariviere 1999).

Economic Importance for Humans: Negative

None known.

Conservation Status

The Neotropical otter shows little fear of humans. All over its range the animal has been hunted for its valuable and beautiful pelt. The durable fur of river otters is used for coat collars and trimming. One estimate has about 30,000 otters being killed annually in Columbia and Peru alone during the 1970's (Nowak 1999).

During the period 1950-1970 L. longicaudis was heavily hunted and its numbers diminished greatly. From 1959-1972, at least 113,718 pelts were exported from the Peruvian Amazon. In Peru in 1970, over 14,000 pelts were exported and some believe this was only 50% of the animals killed (Lariviere 1999).

The Neotropical river otter is listed as endangered by the United States Department of the Interior, Appendix 1 of CITES, and also by the Mexican Ministry of Ecology. It is currently protected by many countries in its range including Argentina, Bolivia, Brazil, and many others (Lariviere 1999).

In Mexico, L. longicauda has disappeared from the highlands. Habitat destruction and fragmentation threatens the otter in the rest of the country (Nowak 1999).

In Argentina, due to excessive hunting in the 1970's, otter populations became very low. Once they received full protection in 1983, their populations recovered rapidly. Continued illegal hunting, water pollution and habitat destruction through ranching and mining are likely causes for the rareness of L. logicaudis (Lariviere 1999). A study of the wildlife in the lower delta of the Parana River in Argentina also shows that extraordinary floods in combination with human pressure has endangered the L. longicauda population there (Quintana et al 1992).

Other Comments

There are other common names for Lontra longicaudis including the Amazonian river otter and water dog. Sometimes these otters are kept in captivity and are trained by fishermen to capture fish (Lariviere 1999).

There has been some debate regarding the generic-level taxonomy for this otter; recently, New World river otters were given the name Lontra rather than Lutra (Lariviere 1999).

Fossil evidence for L. longicauda is unavailable. However, ca. 1.7 million years ago, Neotropical otters separated from marine otters. This corresponds somewhat to the dispersal of otters into S. America (2-3 million years ago) (Lariviere 1999).

Evidence from phylogenetic relationships of otters, based on mitochondrial cytochrome b sequences, suggests otters can be divided into three primary clades. Neotropical otters are grouped with the North American river otters and marine otters. The results of this study suggest a rapid evolutionary radiation. The three species of Lontra form a well-supported monophyletic grouping (Koepfli and Wayne 1998).

Contributors

Kathleen Berry (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

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.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

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.

chemical

uses smells or other chemicals to communicate

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

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.

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).

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.

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

tactile

uses touch to communicate

viviparous

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

year-round breeding

breeding takes place throughout the year

References

Chanin, P. 1985. The Natural History of Otters. New York and Oxford: Facts on File Publications.

Helder, J., H. DeAndrade. 1997. Food and feeding habits of the neotropical river otter Lontra longicaudis (Carnivora, Mustelidae). Mammalia, 61:(2): pp. 193-203.

Koepfli, K., R. Wayne. Dec 1998. Phylogenetic relationships of otters (Carnivora:Mustelidae) based on mitochondrial cytochrome b sequences. Journal of Zoology, 246: pp. 401-416.

Lariviere, S. 1999. Lontra longicaudis. Mammalian Species, 609: 1-5.

Nowak, 1999. New World River Otters. Walker's Mammals of the World, Vol 1: pp. 740-741.

Pardini, R. 1998. Feeding ecology of the neotropical river otter Lontra longicaudis in an Atlantic Forest stream, south-eastern Brazil. Journal of Zoology, 245: pp. 385-391.

Pardini, R., E. Trajano. 1999. Journal of Mammalogy, 80(2): 600-610.

Quintana, R., R. Bo, J. Merler, P. Minotti, A. Malvarez. 1992. Use and situation of wildlife in the lower delta of the Parana River. Iheringia Serie Zoologia, 0(73): 13-33.

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