Neotropical otter

The neotropical otter or neotropical river otter (Lontra longicaudis) is a near-threatened (per the IUCN) otter species found in freshwater systems from Mexico and Central America through mainland South America, as well as the island of Trinidad. It looks similar to the northern (L. canadensis) and southern river otter (L. provocax), which live north and south of its home range. Its body can be from 36 to 66 centimetres long (14 to 26 inches), with a tail from 37 to 84 centimetres (15 to 33 inches). It weighs between 5 and 15 kilograms (11 to 33 pounds).

This otter lives in many different types of river areas and lands next to rivers. You can find it in places with tropical and cold-evergreen forests, wide open grassy lands called savannas, special flat lands called llanos in Colombia and Venezuela, and a huge wet area called the pantanal in Bolivia, Brazil and Paraguay. It likes clear, fast-moving rivers and streams, especially where it does not have to share space with the bigger and louder giant otter (Pteronura brasiliensis). Unlike some other otters that live in groups, the neotropical otter usually lives alone. It eats mostly fish and small creatures that live in water, like crabs and shells.

Taxonomy

The family name for the neotropical otter has been discussed, but using Lontra for otters in the New World is widely accepted. These otters live across much of South America, so it makes sense that some groups are separated by geography. For example, the Cordillera Mountains and rivers can keep otter groups apart.

Neotropical otters share similarities with the marine otter and southern river otter, both also found in South America. But they are quite different from the giant otter, even though they live in similar areas and use similar habitats.

Subspecies

Research in southern Brazil found that these otters have a lot of genetic variety. This suggests they might be becoming more diverse recently. Based on this, scientists recognize three subspecies:

• Lontra longicaudis annectens
• Lontra longicaudis enudris
• Lontra longicaudis longicaudis

A newer study in 2024 found that the northern group, L. l. annectens, has a very different genetic makeup. Some scientists now call this group the Northern Neotropical river otter or Mesoamerican river otter (L. annectens).

Description

The Neotropical otter has short, dark grayish-brown fur, with lighter coloring around its muzzle and throat. These otters have long, wide tails, short sturdy legs, and fully webbed toes. Males are about 25% larger than females. Their head and body measure between 36 and 66 centimeters (14 to 26 inches), and their tail adds another 37 to 84 centimeters (15 to 33 inches). They can weigh from 5 to 15 kilograms (11 to 33 pounds).

Neotropical otters talk to each other using scent marks, and they may also use whistles, hums, and screeches. Their teeth are usually the same as Eurasian otters, with three incisors, one canine, four premolars, and one molar on the top, and three incisors, one canine, three premolars, and two molars on the bottom.

Distribution and habitat

The Neotropical otter lives in many places, from northwest Mexico all the way to central Argentina. They like clear, fast-moving rivers and usually avoid slow, muddy water or swampy areas. These otters can be found between 300 and 1,500 meters above sea level, but sometimes they live as high as 3,000 meters. They need dense plants near the water and like to rest in solid, dry spots close to deep water.

Neotropical otters can live in many different places besides rivers, such as rice fields, sugar cane farms, places where water flows out, and even some lakes. They sometimes go to the beach and play in salty water, hunting small sea creatures.

Ecology and behaviour

The Neotropical otter mainly eats fish and crustaceans, which make up most of its diet. It also sometimes eats mollusks, small mammals, birds, large insects, fruits, and even aquatic insects like dobsonfly larvae when fish are hard to find. The otter’s food choices can change with the seasons. For example, during dry seasons when fish are scarce, it may eat more frogs.

Breeding happens mostly in spring. After a 56-day gestation, females give birth to between 1 and 5 pups. The pups are born blind but have fur. They start leaving the nest around 52 days old and can swim by 74 days. Mothers raise the pups alone, as males do not help. The mother must protect her pups from other otters. Otters choose dens based on factors like water level, food availability, and safety. They prefer dens near fresh water, with good food supplies, and in deep, wide water areas. These otters like quiet forests and avoid places where humans clear land for farming.

Neotropical otters mark their territory by scratching or leaving scent in places like rocks and under bridges. They often mark near their dens. When two otter species share the same area, such as the giant otter, they may compete for food, but in some places they can live together without much trouble.

Conservation

The Neotropical otter is listed as Near Threatened by the IUCN. It is protected in Argentina and many other South American countries. In the past, many otters were hunted for their fur, which caused them to disappear from some areas. Today, the otter still faces threats from illegal hunting, loss of homes due to mining and farming, and water pollution.

Some people who fish feel upset because otters eat fish they might catch. During dry times, both people and otters search for fish in deeper water, which can lead to more competition. Studies show that local fishermen understand a lot about otters and share similar facts with scientists. Fishermen say otters sometimes break their fishing tools but do not harm nets used for crabs and shrimp. Ideas to help both groups include paying fishermen to share information about otters, which could help protect them better while also supporting local people. Otters very rarely get stuck and hurt in fishing nets.

These otters are also at risk because their homes are being damaged by farming, polluted soil, dirty water, roads, and runoff. When forests are cleared for cattle, the plants near streams that otters like are removed or trampled. These otters are important for showing the health of their environment because they need clean water and rich habitats to live, and they do not have many babies.

In captivity

Two Neotropical otters, one male and one female, were brought to Santa Fe Zoological Park in different years. The zookeepers saw them mating in the water but then kept them apart. The female otter had three babies, but only one survived. Some people think the mother might have accidentally hurt the other babies because her space was too small and she couldn’t swim around like she would in the wild. Scientists learned that the female carried her babies for 86 days before birth, which is longer than they used to think. They aren’t sure why it took so long—maybe it’s different for this group of otters, or maybe the zookeepers just missed something happening.