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).
Perception Channels: tactile ; chemical
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).
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: data deficient
None known.
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).
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.
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.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
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
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).
Range mass: 5 to 15 kg.
Range length: 360 to 660 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
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).
Known Predators:
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.
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 gestation period: 56 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation
Average gestation period: 57 days.
Average number of offspring: 2.5.
The Neotropical otter or Neotropical river otter (Lontra longicaudis) is an otter species found in Mexico, Central America, South America, and the island of Trinidad. It is physically similar to the northern and southern river otter, which occur directly north and south of this species' range. Its head-and-body length can range from 36–66 centimetres (14–26 in), plus a tail of 37–84 centimetres (15–33 in). Body weight ranges from 5–15 kilograms (11–33 lb).[3] Otters are members of the family Mustelidae, the most species-rich (and therefore diverse) family in the order Carnivora.
This otter is found in many different riverine habitats, including deciduous and evergreen forests, savannas, llanos and pantanal. It prefers to live in clear fast-flowing rivers and streams. It is a relatively solitary animal and feeds mostly on fish and crustaceans.
The taxonomy of the genus Lontra has been debated, but the use of Lontra rather than Lutra for New World otters is generally supported. The Neotropical otter has a very wide range, covering a large portion of South America, so it is not surprising there are geographical structures separating some populations. One such geographical isolation is the Cordillera Mountains. Additionally, the river in the Magdellena river valley flows north, away from the mountains, decreasing the likelihood that otters in the northern tip of South America will mix with otters elsewhere in the continent.
Neotropical otters have an unusual phylogenic relationship to other otter species. They are most similar to marine otter (Lontra felina) and southern river otter (Lontra provocax), which is not surprising considering these two species are found in South America. However, Neotropical otters are relatively distantly related to giant otter (Pteronura brasiliensis), which is surprising considering they have nearly identical ecological niches and home ranges.[4]
In one study, otters within a 1,600 square mile area in southern Brazil showed low nucleotide variation, but high haplotype diversity compared to other otter species and other carnivores. The study made the conclusion that otters may be undergoing a recent increase in diversity. The results also show interrelatedness of otters nearby and give reason to separate the species into subspecies:[5]
The Neotropical otter is covered in a short, dark grayish-brown pelage. Fur color is lighter around the muzzle and throat.[6] They possess a long wide tail, with short stout legs and fully webbed toes. Sexually dimorphic, the males are about 25% larger than the females.[7] Its head-and-body length can range from 36–66 centimetres (14–26 in), plus a tail of 37–84 centimetres (15–33 in).[3] Body mass of the otter generally ranges from 5 to 15 kilograms (11-33 pounds). Neotropical otters will communicate with nearby otters via scent marking. Communication may also occur via whistles, hums, and screeches.[7]
The dental formula seldom varies from that of Eurasian otters (Lutra lutra), except in the few cases of otters that have dental anomalies.[8] Females and males have the same formula. The dental formula (for half the skull) is as follows:[9]
The Neotropical otter has the widest distribution of all the Lontra species. Their habitat can range from northwest Mexico to central Argentina. They prefer clear, fast-flowing rivers, and are rarely known to settle in sluggish, silt-laden lowland waters or boggy areas. While mostly occurring at 300 to 1500 m above sea level, they have been found settled at 3000 m.[10] They require dense riparian vegetation and abundant den sites but, other than that, the Neotropical otter is very versatile and tolerant to environmental change. The otters prefer den sites that are solid, high, dry, and in proximity to deep water.[11] The Neotropical otter is the greatest generalist of all otter species. In addition to rivers and streams, they can settle in and exploit some rather formidable habitats, such as wastewater treatment plants, rice paddies, sugar cane plantations, estuaries, deltas, drainage ditches, and sometimes swamps. They can inhabit cold, glacial lakes and streams in the Andes of Ecuador and Colombia.[12] Neotropical otters will also venture to the seashore and beaches (maintaining an almost "brackish" lifestyle), hunting marine creatures and playing in the highly saline water.[13]
The Neotropical otter's diet consists mostly of fish and crustaceans making up 67% and 28%, respectively, of its total diet. The otter will also occasionally feed on mollusks and small mammals, as well as birds, large insects and fruits.[14][15] This otter is known to occasionally attack fishnets for a source of prey, hindering fishing productivity.[13] Otters living near marine habitats can have a much higher proportion of crustaceans in their diets.
Seasonality also greatly affect otters' food choice. During the dry season, when less fish and crustaceans are available, one study found a higher proportion of frogs in otters' diet. Though, during this time, anurans and reptiles still made up a very small percentage of the total diet. This might also be due to the fact that certain frogs mate during the dry season, so the frogs are easier prey. All in all, the distribution of available food species in a particular area roughly correlates to the percentage of each species found in otters' diet.[16]
Breeding occurs mostly in spring. Gestation will last 56 days and produce a litter of 1–5 pups.[6] The pups are born blind yet fully furred. They will emerge from their mother's nest when about 52 days and begin swimming at 74 days. They are raised completely by their mother, as males do not provide any parental care.[11] The male will only spend a single day with the female during breeding season. The female must keep her pups safe from predation by other Neotropical otters. In one captive breeding situation, cannibalism by the mother may have occurred, though it was not confirmed.[17]
In an ecologically healthy area, there are many possible shelters so an individual can choose its preferred den. However, studies show that not all possible shelters are occupied and not all shelters are equally utilized by Neotropical otters. Otters visit different shelters with varying frequencies, from once or few times per up to many times per year. One factor that influences their preference for a den has to do with the water level, especially during flood season, when a den near water level can easily be washed away. A den may be at the water level, near the bank, or more than 1.5 meters about the water level.[18]
There are many other factors influencing otters' preferences for a shelter. Neotropical otters prefer dens near fresh water, high food availability, and relatively deep and wide water. During seasons with low water, individual otters may be more clumped because they will all move into areas of a river with deeper water, with more fish.[18] Deep, wide pools have been found to have a greater diversity of fish, preferential for otters. Some studies show that otters will forgo a less preferable, but more available den, like a muddy river bank, to spend more time in a preferential den, like a rocky shore.[19]
Neotropical otter females will rear pups in a den without a male. In some cases, a female may find a den that has space to keep her pups and a separate area for her own space. A study of a male otter's movement over 35 days showed he used three different dens without communication between them. Also, this individual moved between two islands separated by a one-kilometer wide estuary. He spent some time in a site with heavy mud, poor substrate for a den, so he may have been on the move to find food.[20]
Dens may have more than one opening, so the otter can easily exit to forage for food while staying safe from predators. There are many classifications of dens that Neotropical otters may use. A cavity among stones or under tree roots is preferred. In certain parts of South America, an otter may come across a limestone dissolution cavity or a cavity in a rocky wall. Though lacking a source of light, the Neotropical otter can make great use of this sturdy home. As a last resort, an otter expend energy to excavate a space among vegetation or a river bank, though those homes are less sturdy. Vegetative cover is also very important for the Neotropical otter. In comparison to other otter dens, the Neotropical otter dens do not have holes directly into the water, they do not use plant material as bedding, and will live in caves without light. They are elusive creatures and prefer undisturbed forests without signs of human activity. When humans clear forests for agricultural land, the number of available otter habitats plummets.[18]
Like other otter species, Neotropical otters will mark their territory with scratching or spraint (feces) in obvious places like rocks and under bridges.[21] Signs of marking may be most concentrated around their dens. They tend to only mark in certain areas of the den, separate from the activity center of the den. In caves, where a water sources may leak through the walls and wash away the scent, the resident may mark areas inside their den.[18]
The niches and ranges of the giant otter and the Neotropical otter overlap widely. Both species are diurnal and mainly piscivorous. The giant otter is less of a generalist in habitat, preferring slow-moving water and overhanging vegetation, but where the Neotropical otter may also occur. The giant otter is much larger and hunts in groups, so it can take larger prey. Some areas, like the Pantanal, have high enough productivity such that both otter species can coexist with little or no competition (niche partitioning). Additionally, Neotropical otters prefer deeper and wider streams than giant otters.[12]
The Neotropical otter is listed as Near Threatened by the IUCN. The species is currently protected in Argentina and many other South American countries. Heavy hunting for its fur in the 1950s–1970s resulted in much local extinction over the otter's range. Illegal hunting, habitat destruction through mining and ranching, and water pollution still affect the population of the Neotropical otter.[22] Although there have been attempts at captive breeding, these attempts have been largely unsuccessful.[6]
Most negative feelings about otters arise from fishermen who compete with the otter for fish. More data is needed to determine how much overlap exists between the fishermen's desired catch and the otter's diet. The highest competition between Neotropical otters and fishermen occurs during drought conditions. Fishermen may move out of their regular fishing areas, into deeper pools where the otter usually hunts in the absence of people. In a study on local fishermen's attitudes, the study revealed that fishermen's knowledge aligned with scientific data about the Neotropical otter's behavior, body description, and other data. Because the fishermen's facts aligned with scientific knowledge, scientists could then trust the fishermen's first-hand accounts about problems they experience with otters. Fishermen reported that otters will damage their fishing gear, but do not damage crab and shrimp nets. The locals have varying opinions about the otters' presence, from understanding they have to share space with the otters to wanting to kill the otters. Fishermen's knowledge and frequent contact with this elusive species might qualify them as the best managers of the species. There have been proposals to subsidize their fish profits lost to otters. However, it might be more beneficial to pay them to collect data on the species. This would benefit fishermen economically, improve fishermen's attitude toward the animal, and build on to currently insufficient data about this species. Fishermen usually have the greatest knowledge of the resource. Otters are rarely victims of being caught in gillnets, themselves, and very rarely die from the same cause.[23]
Neotropical otters are threatened by habitat degradation associated with: agriculture, soil compaction, pollution, roadways, and runoff. Also, when forests are cleared for cattle grazing, heavy vegetation (which is the otter's preferred habitat) near streams is also cleared or trampled by cattle. This species is a very important ecological indicator because they prefer ecologically rich, aquatic habitats and have a low reproductive potential.[19]
One male and one female Neotropical otter were captured near Caucasia, Colombia and taken to Santa Fe Zoological Park in 1994 and 1996, respectively. Zoo staff observed the pair mating in the water, then separated the animals. The female had three births; one was successful. The infant deaths may have been unintentionally caused by the mother. One idea suggested the mother's enclosure was too small and she had no access to water, as she would have had in the wild. The mother's gestation period was 86 days for two separate breeding events recorded at this zoo. An 86-day gestation period is much longer than the previously accepted belief that gestation lasts around 60 days. Two possible explanations are: differences might exist between different subspecies or a later copulation may have occurred and not been observed. Also, this otter species might display short-term variation in gestation periods.[17]
The Neotropical otter or Neotropical river otter (Lontra longicaudis) is an otter species found in Mexico, Central America, South America, and the island of Trinidad. It is physically similar to the northern and southern river otter, which occur directly north and south of this species' range. Its head-and-body length can range from 36–66 centimetres (14–26 in), plus a tail of 37–84 centimetres (15–33 in). Body weight ranges from 5–15 kilograms (11–33 lb). Otters are members of the family Mustelidae, the most species-rich (and therefore diverse) family in the order Carnivora.
This otter is found in many different riverine habitats, including deciduous and evergreen forests, savannas, llanos and pantanal. It prefers to live in clear fast-flowing rivers and streams. It is a relatively solitary animal and feeds mostly on fish and crustaceans.
