River Otters - Living with Wildlife | Washington Department of Fish & Wildlife River Otters For more information on the Living With Wildlife series, contact the WDFW Wildlife Program 360-902-2515 Figure 1. River otters are powerful swimmers with snakelike agility; their small eyes are adapted for seeing food items in murky or dark water. (From Larrison, Mammals of the Northwest: Washington, Oregon, Idaho, and British Columbia.) • River otters (Lutra canadensis, Fig. 1) have long, streamlined bodies, short legs, webbed toes, and long, tapered tails—all adaptations for their mostly aquatic lives. Their short thick fur is a rich brown above, and lighter, with a silvery sheen, below. Adult male river otters average 4 feet in length, including the tail, and weigh 20 to 28 pounds. Female adults are somewhat smaller than males. Although seldom seen, river otters are relatively common throughout Washington in ponds, lakes, rivers, sloughs, estuaries, bays, and in open waters along the coast.

In colder locations, otters frequent areas that remain ice-free in winter—rapids, the outflows of lakes, and waterfalls. River otters avoid polluted waterways, but will seek out a concentrated food source upstream in urban areas. River otters are sometimes mistaken for their much larger seagoing cousin, the sea otter (Enhydra lutris, Fig. 2). However, male sea otters measure 6 feet in length and weigh 80 pounds. Sea otters are acclimated to salt water, and come to shore only for occasional rest periods and to give birth. In comparison, river otters can be found in fresh, brackish, or salt water, and can travel overland for considerable distances. Facts about Washington River Otters Food and Feeding Habits River otters are opportunists, eating a wide variety of food items, but mostly fish. River otters usually feed on 4- to 6-inch long, slowly moving fish species, such as carp, mud minnows, stickle backs, and suckers. However, otters actively seek out spawning salmon and will travel far to take advantage of a salmon run.

River otters can smell concentrations of fish in upstream ponds that drain into small, slow moving creeks, and will follow the smell to its origin, even in urban areas. River otters also eat freshwater mussels, crabs, crayfish, amphibians, large aquatic beetles, birds (primarily injured or molting ducks and geese), bird eggs, fish eggs, and small mammals (muskrats, mice, young beavers). In late winter, water levels usually drop below ice levels in frozen rivers and lakes, leaving a layer of air that allows river otters to travel and hunt under the ice. River otters digest and metabolize food so quickly that food passes through their intestines within an hour. Den Sites River otters use dens for giving birth and for shelter from weather extremes. Birthing dens are lined with small sticks, shredded vegetation, and other available material. Den sites include hollow logs, log jams, piles of driftwood or boulders, and abandoned lodges and bank dens made by nutria or beaver. Dens are well hidden; those located at the water’s edge will have an entry far enough below the surface to prevent it from being seen and/or frozen shut.

River otters also den under boathouses, duck blinds, and other human structures up to ½ mile away from water. Figure 2. The river otter is sometimes mistaken for its much larger seagoing cousin, the sea otter (shown here). (From Christensen and Larrison, Mammals of the Pacific Northwest: A Pictorial Introduction.) Reproduction and Family Structure River otters have what is called delayed implantation; the fertilized egg does not attach to the uterine wall for a period of time after breeding. Thus, gestation ranges from 285 to 375 days. Two to four pups are born March through May. Young otters begin playing at four weeks of age and learn to swim at about seven weeks of age. When eight to ten weeks of age, the pups begin exploring beyond their den and are introduced to solid food. In late fall, the pups leave to establish their own territories. During this time, wandering youngsters are seen far from water, traveling on land between lakes, ponds, and from one stream drainage to another. The basic social group for river otters is a female and her offspring.

(Before and after breeding, male otters usually lead solitary lives.) Mortality and Longevity Essentially safe from predators while in water, river otters are more vulnerable when they travel on land. Predators take mostly young river otters and include coyotes, bobcats, domestic dogs, cougars, and bears. Humans trap river otters to control fish predation in private ponds and commercial fish hatcheries and to prevent damage to private property. The most significant impacts on river otter populations include reduced water quality from chemical pollution and soil erosion, and stream-bank habitat alteration by developments. Viewing River Otters River otters are active day and night; around humans they tend to be more nocturnal. Otters spend their time feeding and at what appears to be group play. They also dry their fur, groom themselves, and mark their territory by vigorously scratching, rubbing, and rolling on the ground. River otters are active year round, and, except for females with young in a den, are constantly on the move. They tend to follow a regular circuit that is covered in one to four weeks. Males can travel 150 miles within a particular watershed and its tributaries in a year.

A family may range 10 to 25 miles in a season. To observe river otters, sit quietly on a high place (a bridge, overhanging bank or tree, or pier) above a known feeding area, trail, or slide. Find an angle from which you can avoid surface glare. A pair of polarized sunglasses and binoculars is useful. River otters are wary and their hearing and sense of smell are well developed. However, they are fairly nearsighted and they may not notice you if you stay still. Never instigate a close encounter with river otters. They have been known to attack humans, and females with young are unpredictable. Trails and Tracks When traveling on land river otters walk, run, or bound. Bounding is their fastest gait. When bounding, the front and hind feet are brought toward each other causing the back to arch and the tail to be lifted off the ground. Otters make trails along the edges of lakes, streams, and other waterways. Trails often lead from one cove to another across a small peninsula, or alongside shallow rapids. Trails are 6 to 7 inches wide and may lead to slides or dens.

Look for tracks in soft mud, damp sand, or fresh snow (Fig. 3). Figure 3. River otter tracks show five pointed toes around a small heel pad. Tracks are 3 to 3½ inches wide and 3 to 4 inches long. (Washington Department of Fish and Wildlife.) Slides Slides are a common sign of river otter presence and there are often several in a river otter’s home range. Slides are about 1 foot wide and located at water’s edge—frequently on islands in lakes, or in openings under bushes or brambles along creeks and streams. Slides are made in grass, dirt, sand, or snow. There is often a trail from the water’s edge to the slide. Droppings River otters thoroughly chew their food, so their droppings contain only fine bits of fish scales, bones, and shells. The texture is oily, the smell fishy. Droppings are left on prominent spots at the water’s edge, along trails, and near dens. Fresh river otter droppings are shapeless, slimy, and green; they darken with age.

Calls River otter sounds include chirps (similar to a marmot), growls, whines, and, when alarmed, an explosive hah! Preventing Conflicts Figure 4. An existing wire fence can be modified to keep otters out of an area by adding wire to the bottom three feet. Keep the bottom flush with the ground or bury it 6 inches. Figure 5. Where otters seem intent on entering from underneath the fence, include a wire apron on the animal side of the fence. Figure 6. Keep river otters out of ponds and other areas with two hot wires, 6 and 10 inches off the ground. Make sure these are well marked to prevent accidents. (Drawings by Jenifer Rees.) River otters are often blamed for preying on wild game fish, particularly trout. Nevertheless, studies indicate that the bulk of the river otter’s diet consists of non-game fish species. However, river otters—particularly families containing young pups in spring—occasionally cause severe problems in fish hatcheries and private ponds. Otters also den under houses, decks, and other structures near water, and the smell of their droppings and discarded food remains can be unpleasant.

To prevent conflicts or remedy existing problems: Eliminate access to feeding sites and other areas. Because river otters have heavy bodies and aren’t jumpers, a 4-foot high fence constructed with 3-inch mesh wire can keep them out of an enclosed area, such as where fish or aquaculture activities are concentrated (Fig. 4). Because river otters are strong, fences should be sturdy and extend 6 inches below the surface to prevent otters from pushing under the fence. Alternatively, include a wire apron on the animal side of the fence to prevent otters from entering from underneath (Fig. 5). A double-wire electric fence, with wires set 6 and 10 inches above ground will also deter river otters. Such a fence can stand alone, or supplement an existing perimeter fence (Fig. 6). A single wire can be used around docks and houseboats. River otters are resourceful and will thoroughly investigate fence lines to find a way into a food source. They are known to use abandoned animal burrows as routes under fences. So, inspect fences regularly to make sure river otters have not dug or pushed their way under or worked their way over them. Provide fish with hiding places.

Give fish safe places to hide by constructing sturdy hiding places on the bottom of ponds using cinder blocks, ceramic drain tile, wire baskets made from leftover galvanized fencing, or upside-down plastic crates held in place with heavy rocks. In larger ponds, attach a group of cut conifer trees to a heavy anchor on the bottom of the pond. Eliminate access to convenient denning sites. Close potential entries under porches, houses, sheds, and other structures with ¼-inch mesh welded-wire (hardware cloth), boards, or other sturdy material (Fig. 7). Aluminum flashing, or aluminum or stainless-steel hardware cloth is recommended in saltwater areas since galvanized materials quickly corrode. Eliminate noxious odors. Commercial odor-eliminators can be used to remove the smell of otter droppings and other debris under structures. Such products are available through hospital supply houses, drugstores, pet stores, and from the Internet using the keywords “Pest Control Supplies.” If the smell is really bad, the beams and other areas under the structure may have to be cleaned with a bleach solution (1½ cups of household bleach in 1 gallon of water). Be very careful of fumes. Figure 7.

Eliminate potential entries under porches, houses, sheds, and other structures with ¼-inch mesh welded-wire (hardware cloth), boards, or other sturdy material. (Drawing by Jenifer Rees.) River Otter in or Under Buildings Occasionally a river otter will find a suitable den site in or under a building. Otters normally occupy a den site for only two or three consecutive nights. However, during the mating and nesting season, females are attracted to warm, dry, dark, easily defended areas, and will remain longer if the setting remains favorable. You may choose to let otters occupy an area, such as under an outbuilding, if they don’t pose a problem. Should you choose to remove the animals, a wildlife control company can be hired (call your local Fish and Wildlife office for a current list of contacts), or you can complete the process yourself using the steps below. (For detailed information, see Evicting Animals from Buildings .) 1. Seal all openings except the main entrance used by otters. Use sturdy wire mesh (1/4-inch hardware cloth or similar materials) to screen vents near ground level in houses and other structures.

Tightly seal holes in foundations or under porches to prevent otters from entering (Fig. 7). 2. To determine entry points, you can use "tracking patches" of a fine layer of sand, flour, or dust placed at suspected entrances. Wadded up newspaper lightly stuffed into the entry hole also works great. Otters will push the paper out of the way when exiting. 3. After dark, when the otter has left seeking food they will leave tracks at the den entrance. Inspect the powder or the dislodged newspaper for exiting otter tracks. 4. Once a otter has left the building, immediately seal the entrance with a hardware cloth "one-way door" (Fig. 8). (You will not want to permanently exclude at this point, not being sure of the number of otters present.) The one-way door can be made from 1/4 -inch hardware cloth that is attached over the opening, and hinged at the top and left loose on the other 3 sides. It should be larger than the opening so that it cannot swing inward. The otter will push it open to leave, but cannot re-enter. 5.

Put a layer of flour on the inside and outside of the door after the one-way door has been installed for two to three nights. Any footprints in the flour should be outside the door with none inside. This means the otter is out. If you have any doubt, then smooth out the dirt on both sides of the door with your hand or a tool, reapply the flour and observe. Once a couple of days have gone by with no footprints, the skunk is probably gone. Another way to check is to open the door and shove a few pieces of wadded up newspaper into the otter’s entrance. If the paper stays in place for two to three nights, then the otter is gone. 6. Once you are sure all otters are out, permanently seal the opening. Important Note: Be sure all animals are out before sealing up the entrance. Pay close attention and use extra caution if trying this option March through May when babies may be in the den. Figure 8. A one-way door can be used in conjunction with a welded wire or hardware cloth barrier. (Drawing by Jenifer Rees.) To try and drive an otter away, consider harassing the animal.

Lighting up the den site with battery operated flashing lights and adding a portable radio can cause a otter to seek a more suitable habitat. (For detailed information, see Evicting Animals from Buildings .) Trapping and Lethal Control Trapping or shooting river otters should be a last resort. Lethal control can never be justified without a serious effort to first prevent problems from recurring. Removing river otters by any means is a short-term solution since other otters are likely to move in if attractive habitat is still available. (For detailed information, see Trapping Wildlife .) Public Health Concerns Diseases and parasites associated with river otters are rarely a risk to humans. Canine distemper, a disease that affects domestic dogs, may be found in Washington river otter populations. Have your dogs vaccinated for canine distemper to prevent them from contracting the disease. Giardia and Cryptosporidium are also found in river otters around the Puget Sound area. These could be a public health concern for immunocompromised people. Anyone handling a river otter should wear rubber gloves, and wash their hands well when finished.

Legal Status The river otter is classified as a furbearer ( WAC 232-12-007 ). A trapping license and open season are required to trap river otters. A property owner or the owner’s immediate family, employee, or tenant may kill or trap a river otter on that property if it is damaging crops or domestic animals ( RCW 77.36.030 ). No permit is necessary; however, you must notify the Washington Department of Fish and Wildlife immediately after taking a river otter in these situations. Because legal status, trapping restrictions, and other information about river otters change, contact your local state wildlife office for updates. Additional Information Books Christensen, James R., and Earl J. Larrison. Mammals of the Pacific Northwest: A Pictorial Introduction. Moscow, ID: University of Idaho Press, 1982. Hygnstrom, Scott E., et al. Prevention and Control of Wildlife Damage. Lincoln, NE: University of Nebraska-Lincoln, Institute of Agriculture and Natural Resources, 1994.

(Available from: University of Nebraska Cooperative Extension, 202 Natural Resources Hall, Lincoln, NE 68583-0819; phone: 402-472-2188; also see Internet Sites below.) Ingles, L. G. Mammals of the Pacific States. Stanford, CA: Stanford University Press, 1965. Larrison, Earl J. Mammals of the Northwest: Washington, Oregon, Idaho, and British Columbia. Seattle: Seattle Audubon Society, 1976. Link, Russell. Landscaping for Wildlife in the Pacific Northwest. Seattle: University of Washington Press and the Washington Department of Fish and Wildlife, 1999. Maser, Chris. Mammals of the Pacific Northwest: From the Coast to the High Cascades. Corvalis: Oregon State University Press, 1998. Verts, B. J., and Leslie N. Carraway. Land Mammals of Oregon. Los Angeles: University of California Press, 1998.

Internet Resources (General) River Otters: Maine IF&W River Otters Figure 1: Drawing Credit - Larrison Overview River otters (Lontar canadensis, Fig. 1) have long, streamlined bodies, short legs, webbed toes, and long, tapered tails, all adaptations for their mostly aquatic lives. Their short, thick fur is a rich brown above, and lighter, with a silvery sheen, below. Adult male river otters average four feet in length, including the tail, and weigh 20 to 28 pounds. Female adults are somewhat smaller than males. Although seldom seen, river otters are relatively common throughout Maine in ponds, lakes, rivers, sloughs, and streams as well as in estuaries, bays, and open waters along the coast. In colder locations, otters frequent areas that remain ice-free in winter, rapids, the outflows of lakes, and waterfalls. River otters avoid polluted waterways, but will seek out a concentrated food source upstream in urban areas. River otters are powerful swimmers with snakelike agility; their small eyes are adapted for seeing food items in murky or dark water. (Fig.

1) Facts about Maine River Otters Food and Feeding Behavior River otters are opportunists, eating a wide variety of food items, but mostly fish. River otters usually feed on slow moving fish, such as carp, mud minnows, stickle backs, and suckers, that are from four to six inches long. River otters can smell concentrations of fish in upstream ponds that drain into small, slow moving streams and will follow that smell to its origin, even in urban areas. River otters also eat freshwater mussels, crabs, crayfish, amphibians, large aquatic beetles, birds (primarily injured or molting ducks and geese), bird eggs, fish eggs, and small mammals (muskrats, mice, young beavers). In late winter, water levels usually drop below ice levels in frozen rivers and lakes, leaving a layer of air that allows river otters to travel and hunt under the ice. River otters digest and metabolize food so quickly that it can take only an hour for food to pass through their intestines. Den Sites River otters use dens for giving birth and for shelter from extreme weather. Birthing dens are lined with small sticks, shredded vegetation, and other available material.

Den sites include hollow logs, log jams, piles of driftwood or boulders, and abandoned lodges and bank dens made by beaver. Dens are well hidden; those located at the water's edge will have an entry far enough below the surface to prevent it from being seen or frozen shut. River otters also den under boathouses, duck blinds, and other human structures up to half a mile away from water. Reproduction and Family Structure River otters have what is called delayed implantation; the fertilized egg does not attach to the uterine wall for up to eight months after breeding. Thus, actual gestation ranges from 61 to 63 days. Two to four pups are born May through June. Young otters begin playing at four weeks of age and learn to swim at about seven weeks of age. When eight to ten weeks of age, the pups begin exploring beyond their den and are introduced to solid food. In late fall, the pups leave to establish their own territories. During this time, wandering youngsters are seen far from water, traveling on land between lakes, ponds, and streams. They may move from one drainage to another. The basic social group for river otters is a female and her offspring.

Before and after breeding, male otters usually lead solitary lives. Mortality and Longevity Essentially safe from predators while in water, river otters are more vulnerable when they travel on land. Predators, including coyotes, bobcats, cougars, bears, and domestic dogs, mostly take young otters. Humans trap river otters to obtain their pelts, control fish predation in private ponds and commercial fish hatcheries, and prevent damage to private property. Reduced water quality (from chemical pollution and soil erosion) as well as stream-bank habitat alteration from development pose the greatest threats to river otter populations. Back to top Viewing River Otters River otters are active day and night; around humans they tend to be more nocturnal. Otters spend their time feeding and at what appears to be group play. They also dry their fur, groom themselves, and mark their territory by vigorously scratching, rubbing, and rolling on the ground. River otters are active year round and, except for females with young in a den, are constantly on the move. They tend to follow a regular circuit and cover it in one to four weeks. Males can travel 150 miles within a particular watershed and its tributaries in a year.

A family may range 10 to 25 miles in a season. To observe river otters, sit quietly on a high place such as a bridge, overhanging bank or tree, or pier, above a known feeding area, trail, or slide. Find an angle from which you can avoid surface glare. Polarized sunglasses and binoculars are useful. River otters are wary and their hearing and sense of smell are well developed. They are fairly nearsighted, however, and they may not notice you if you stay still. Never instigate a close encounter with a river otter. Otters have been known to attack humans, and females with young are unpredictable. Trails and Tracks Figure 2: Drawing Credit - WDF&W When traveling on land, river otters walk, run, or bound. Bounding is their fastest gait. When bounding, the front and hind feet are brought toward each other causing the back to arch and the tail to be lifted off the ground. Otters make trails along the edges of lakes, streams, and other waterways. Trails often lead across a small peninsula from one cove to another or alongside shallow rapids.

Trails are six to seven inches wide and may lead to slides or dens. Look for tracks in soft mud, damp sand or fresh snow. (Fig. 2) River otter tracks show five pointed toes around a small heel pad. Tracks are three to three and a half inches wide and three to four inches long. (Fig. 2) Slides One-foot wide slices are made in grass, dirt, sand or snow along the edge of water, frequently on islands in lakes or in openings under bushes and brambles along streams. There are often several slides in a river otter's home range. It is common to find a trail leading away from the slide. Droppings River otters thoroughly chew their food, so their droppings contain only fine bits of fish scales, bones, crayfish parts, and fish scales, and shells. The droppings, which smell fishy and have an oily texture, are shapeless, dark, slimy, and green, red, or black. Droppings get lighter as the sun bleaches out the color. Otters deposit their scat at latrine sites, which are prominent locations near at the water's edge, along trails, and near dens.

Many otters frequent the same sites, leaving droppings as a way of communicating with each other. Calls Back to top Preventing Conflicts Although river otters are often blamed for preying on wild game fish, particularly trout, studies indicate that the bulk of the diet consists of non-game fish species. Occasionally -- and it is usually families containing young pups in spring -- otters cause severe problems in fish hatcheries and private ponds. Also, they sometimes den under houses, decks, and other structures near water, and the smell of their droppings and discarded food remains can be unpleasant. To prevent conflicts or remedy existing problems: Eliminate access to feeding sites and other areas. Because river otters have heavy bodies and aren't jumpers, a four-foot high fence constructed with three-inch mesh wire can keep them out of an enclosed area, such as where fish or aquiculture activities are concentrated (Fig. 3). Because river otters are strong, fences should be sturdy and extend six inches below the surface to prevent otters from pushing under the fence. Alternatively, include a wire apron on the animal side of the fence to prevent otters from entering from underneath (Fig. 4).

A double-wire electric fence, with wires set six and ten inches above ground will also deter river otters. Such a fence can stand alone, or supplement an existing perimeter fence. (Fig. 5) A single wire can be used around docks and houseboats. River otters are resourceful and will thoroughly investigate fence lines to find a way to food. They are known to use abandoned animal burrows as routes under fences. Inspect fences regularly to make sure river otters have not dug or pushed their way underneath or worked their way over them. Figure 3: Drawing Credit - Jennifer Rees Figure 4: Drawing Credit - Jennifer Rees Figure 5: Drawing Credit - Jennifer Rees An existing wire fence can be modified to keep otter out of an area by adding chicken wire to the bottom three feet. Keep the bottom flush with the ground or bury the fencing six inches. (Fig. 3) Where otters seem intent on entering from underneath the fence, include a wire apron on the animal side of the fence. (Fig. 4) Keep river otters out of ponds and other areas with two hot wires, six and 10 inches off the ground. Make sure these are well marked to prevent accidents. (Fig.

5) Provide fish with hiding places. Give fish safe places to hide by constructing sturdy hiding places on the bottom of ponds using cinder blocks, ceramic drain tile, wire baskets made from leftover galvanized fencing, or upside-down plastic crates held in place with heavy rocks. In larger ponds, attach a group of cut conifer trees to a heavy anchor on the bottom of the pond. Figure 6 Eliminate access to convenient denting sites. Close potential entries under porches, houses, sheds, and other structures with quarter-inch mesh welded-wire (hardware cloth), boards, or other sturdy material. (Fig. 6) Aluminum flashing, or aluminum or stainless-steel hardware cloth is recommended in saltwater areas since galvanized materials quickly corrode. Eliminate potential entries under porches, houses, sheds, and other structures with quarter-inch mesh welded-wire (hardware cloth), boards, or other sturdy material. Eliminate noxious odors. Commercial odor-eliminators can be used to remove the smell of otter droppings and other debris under structures.

Such products are available through hospital supply houses, drugstores, pet stores, and from the Internet using the keywords "Pest Control Supplies." If the smell is really bad, the beams and other areas under the structure may have to be cleaned with a bleach solution. (one and a half cups of household bleach in one gallon of water) Be very careful of fumes. River Otters In or Under Buildings Occasionally a river otter will find a suitable den site in or under a building. Otters normally occupy a den site for only two or three consecutive nights. However, during the mating and nesting season, females are attracted to warm, dry, dark, easily defended areas, and will remain longer if the setting remains favorable. You may choose to let an otter occupy an area, such as under an outbuilding, if it doesn't pose a problem. Should you choose to remove the animal, you can hire a wildlife control company (call your local regional Fish and Wildlife office for a current list of contacts), or you can do it yourself. Seal all openings except the main entrance used by otters. Use sturdy wire mesh (quarter-inch hardware cloth or similar materials) to screen vents near ground level in houses and other structures.

Tightly seal holes in foundations or under porches to prevent otters from entering. To determine entry points, you can use "tracking patches" of a fine layer of sand, flour, or dust placed at suspected entrances. Wadded up newspaper lightly stuffed into the entry hole also works great. Otters will push the paper out of the way when exiting. After dark, when the otter goes out in search of food, it will leave tracks at the den entrance. Inspect the powder or the dislodged newspaper. Once an otter has left the building, immediately seal the entrance with a hardware cloth "one-way door" (Fig. 7). You will not want to permanently exclude at this point because you don't know yet how many otters are inhabiting the building. The one-way door can be made from half-inch hardware cloth that is attached over the opening, and hinged at the top and left loose on the other three sides. It should be larger than the opening so that it cannot swing inward. The otter will push it open to leave, but cannot re-enter. After the one-way door has been installed for two or three nights, put a layer of flour on the inside and outside of the door.

If all footprints are outside, and none are inside, then the otter has been shut out. If you have any doubt, smooth the dirt on both sides of the door with your hand or a tool, reapply the flour and observe. Once a couple of days have gone by with no footprints, the otter is probably gone. Another way to check is to open the door and shove a few pieces of wadded up newspaper into the entrance. If the paper stays in place for two to three nights, then the otter is gone. Once you are sure all otters are out, permanently seal the opening. Important Note: Be sure all animals are out before sealing up the entrance. Pay close attention and use extra caution if trying this option during May and June when babies may be in the den. Figure 7 A one-way door can be used in conjunction with a welded wire or hardware cloth barrier. (Fig. 7) To try and drive an otter away, consider harassing the animal. Lighting up the den site with battery operated flashing lights and adding a portable radio can cause an otter to seek a more suitable habitat. Back to top Trapping and Lethal Control Trapping or shooting river otters should be a last resort.

Lethal control can never be justified without a serious effort to first prevent problems from recurring. Removing river otters by any means is a short-term solution as other otters are likely to move in if attractive habitat is still available. (For detailed information, see " Trapping Wildlife ") Back to top Public Health Concerns Diseases and parasites associated with river otters are rarely a risk to humans. Canine distemper, a disease that affects domestic dogs, may be found in Maine river otter populations. Have your dogs vaccinated for canine distemper to prevent them from contracting the disease. Anyone handling a river otter should wear rubber gloves, and wash their hands well when finished. Back to top Legal Status The river otter is classified as a furbearer. A trapping license and open season are required. Because legal status, trapping restrictions, and other information about river otters can change, contact your local Inland Fisheries and Wildlife Regional Office wildlife office for updates. If an otter is causing damage or is a nuisance, consult Maine's laws on this subject . New England Wildlife, Habitat, Natural History, and Distribution Written by: Richard DeGraff, and Mariko Yamasaki University Press of New England, 2001.

Mammals of the Pacific Northwest: A Pictorial Introduction Written by: James R. Christensen, and Earl J. Arrison Moscow, ID: University of Idaho Press, 1982. Prevention and Control of Wildlife Damage Written by: Scott E. Hygnstrom, et al. University of Nebraska-Lincoln, Institute of Agriculture and Natural Resources, 1994. (Available from: University of Nebraska Cooperative Extension, 202 Natural Resources Hall, Lincoln, NE 68583-0819; phone: 402-472-2188; also see Internet Sites below.) Mammals of the Pacific States Written by: Ingles, L. G. Stanford, CA: Stanford University Press, 1965. Mammals of the Northwest: Washington, Oregon, Idaho, and British Columbia Written by: Earl J. Arrison Seattle: Seattle Audubon Society, 1976. Land Mammals of Oregon Written by: B.J. Verts, and Leslie N. Carraway Los Angeles: University of California Press, 1998.

Adapted from: "Living with Wildlife in the Pacific Northwest" Written by: Russell Link, Wildlife Biologist, Email Russell Link , with assistance from WDFW Biologists Rich Beausoleil and Rocky Spencer Design and layout: Peggy Ushakoff, ITT2 Illustrations: As credited Otter | San Diego Zoo Animals & Plants San Diego Zoo Animals & Plants SPECIES: 13 ABOUT Otters are the only serious swimmers in the weasel family. They spend most of their lives in the water, and they are made for it! Their sleek, streamlined bodies are perfect for diving and swimming. Otters also have long, slightly flattened tails that move sideways to propel them through the water while their back feet act like rudders to steer. African Cape clawless otter. The name otter is derived from Old English and Indo European root words that also gave rise to the English word for water. Almost all otters have webbed feet, some more webbed than others, and they can close off their ears and nose as they swim underwater. They like to swim on their back and sides and can see just as well underwater as they can above.

Otters can stay submerged for five to eight minutes, depending on the species, because their heart rate slows, and they use less oxygen. Sea otters are good at floating on the water’s surface, as air trapped in their fur makes them more buoyant. They are much more buoyant than river otters, which have to actively swim to keep afloat. Have you ever noticed that when otters come out of the water, their outer fur sticks together in wet spikes, while the fur underneath still seems dry? That’s because otters have two layers of fur: a dense undercoat that traps air and a topcoat of long, waterproof guard hairs. Keeping their fur in good condition is important, so otters spend a lot of time grooming. In fact, if their fur becomes matted with something like oil, it can damage their ability to hunt for food and stay warm. An otter’s rounded nose has whiskers above the lips that detect water current changes as well as the presence of prey or potential predators lurking in the water. And what do otters have to fear? It depends on where they live. Giant otter young are vulnerable to large cats, anacondas, and caimans.

Sea otters face predation by killer whales, sea lions, and sharks. Small-clawed otters are often killed by domestic dogs. Juvenile spotted-necked otters are prey for fish eagles and monitor lizards. Other otter species must watch out for birds of prey and crocodilians. River otters sliding across snow in Yellowstone. Otters are very energetic and playful. You might say they love to party! They are intelligent and curious, and they are usually busy hunting, investigating, or playing with something. Otters like to throw and bounce things, wrestle, twirl, and chase their tail. They also play games of tag and chase each other, both in the water and on the ground. River otters seem to like sliding down mud banks or in the snow—they’ll do it over and over again! All this activity is part of the otters’ courtship, social bonding, and communication behavior, and since young otters need practice, they tend to be even more playful than the adults. Otters make lots of different sounds, from whistles, growls, and screams to barks, chirps, moans, and coos.

River otters scent mark by using paired scent glands near the base of their tail. These glands produce a strong, musky odor. The scent markings are believed to delineate territorial boundaries and communicate information concerning individual identity, sex, sexual state and receptivity, and time elapsed between scenting visits. This marking behavior looks playful, as the otters rub on logs, roll in piles of fallen vegetation, or grab armfuls of leaves on bushes and trees to rub on their chest and legs, but it has a serious communication purpose in the otter world. Urinating or defecating in the same place is also used as a form of communication. Eurasian otter males form a dominance hierarchy, with the highest-ranking animals occupying the most favorable ranges and marking them accordingly. SaveSave SaveSave HABITAT AND DIET The only continents without otters are Australia and Antarctica, and the only habitats they do not live in are deserts, polar regions, and mountains. The most widely distributed otter is the Eurasian otter, found throughout Europe, North Africa, and Asia to Japan and Indonesia. Typical otter habitat includes both water and land, except for the sea otter, which rarely comes ashore.

Otter species except the sea otter live in dens, most made by other animals, such as beavers. They can also live on rocks or driftwood. Beaver habitat is a great place to find otters, because the otters benefit from the dams and dens beavers build. Typical river otter territory contains a den, with several passages and a dry inner chamber, grassy or sandy places to roll and groom, slides found on muddy banks or snow banks, and feeding sites. Unlike other marine mammals, sea otters do not have a layer of blubber to keep them warm; they rely on warm air trapped in their fur. Sea otters spend hours a day grooming their fur to maintain this "fluffy" protection against cold water. For the sea otter, half of each day is spent diving for food and eating it. Another important daily task for all otters is grooming. They clean their fur not by licking it but by biting and scratching it or rubbing and rolling against grass, rocks, or logs to keep the fur in good condition. The spotted-necked otter is called “fisi maji,” which means water hyena in Swahili.

Otter food may not all come from the ocean, but it is definitely fishy! River otters eat mostly fish, frogs, crayfish, crabs, and mollusks, with an occasional small mammal or bird. Sea otters eat many of the same things, but mostly sea urchins, abalone, crabs, fish, octopuses, mussels, and clams. They crack open clams and mussels with rocks they hold on their stomach—the only otter species to use rocks as tools. Asian small-clawed otters. Most otter species capture prey with their mouth, but Asian small-clawed otters and sea otters have flexible fingers and grab with their hands. Otters have long, sensitive whiskers that help them find prey, even in murky water. Some species, like the Asian small-clawed otter, also use their hands to probe into mud or under rocks to find a tasty meal that might be hiding there. River otters use lots of energy and digest their food very fast, so they eat several times a day. Sea otters need to eat nearly a third of their body weight each day. That’s a lot of abalone!

The otters at the San Diego Zoo are fed a fortified meat-based commercial carnivore diet, carrots, and either squid or trout. They also get treats for enrichment such as crayfish, worms, potatoes, or yams. SaveSave FAMILY LIFE Asian small-clawed otter pup with its family. For most otters, social groups are made up of a mother, her older offspring, and her newest pups; the males spend most of their time alone or with a few other males. During breeding time or where there’s lots of food, though, larger otter groups may gather, especially among sea otters in kelp beds. Most otters are born in a den, helpless and with their eyes closed. The mother takes care of them, often chasing the father away after their birth, although in some species the dad may come back after a few weeks to help raise them. The babies, called pups, are born helpless and pink. They open their eyes and start exploring the den at about one month, learn to swim at two months, and stay with their mother and siblings until they are about one year old, when they head off on their own. Sea otter pup floating on its back with its mother.

For sea otters living in their ocean habitat, it’s a little different—the pups are born with their eyes open, and they have a special coat of hair so they can float, even though they can’t swim yet. They are carried on their mother’s stomach until they are about two months old, when they start swimming and diving on their own. SaveSave SaveSave AT THE ZOO Otters were not often kept in zoos before the 1950s. But the San Diego Zoo’s first otters, two male Pacific otters, arrived in 1934. Our otter collection gradually grew to include giant, Asian small-clawed, smooth-coated, and North American river otters. In 1991, we received our first Eurasian otters, a pair from a zoo in Switzerland. Six years later, they surprised us with a pup, the first of its kind born in the United States! Two spot-neck otters swim at the San Diego Zoo's Lost Forest exhibit. Today, the San Diego Zoo has a Cape clawless otter along Center Street. We are one of just six zoos in the United States to exhibit spotted-necked otters.

You can watch their antics in the Zoo’s Lost Forest, where they live with swamp and spot-nosed monkeys. SaveSave CONSERVATION Endangered giant otters in Manu National Park, Peru It’s hard to determine the wild otter population because of their secretive nature and wide range. There are many studies showing the decline or extinction of otters in certain areas. In most countries, otters are now classified as either threatened or endangered and are under special protection. The North American river otter Lontra canadensis was once in serious trouble because of habitat destruction and trapping, but as a result of reintroduction projects and legal protection, their numbers have increased throughout North America. There are several factors affecting the decline of river otters. The pollution of rivers and waterways is a major threat. Substances such as organic waste from domestic and industrial sources and pesticides used to control insects are often washed into waterways. Oil spills contaminate an otter’s fur, increasing heat loss, reducing buoyance, and proving toxic when ingested. Habitat destruction or loss is also a major factor affecting the river otter. Construction of dams leaves lower rivers dry and unsuitable for river otter populations.

Deforestation affects river otters through much of South America and Asia. Mining rivers for gravel kills the fish that are the otters’ main food source. Changing river courses for flood prevention and agriculture destroys otter habitat. River otters are also hunted and trapped for their pelts or killed by fishermen who see them as competition. And otters often get trapped and drown in fishing nets. California or southern sea otters Enhydra lutris nereis were nearly wiped out a century ago, hunted for their thick fur. An international treaty banned otter hunting in 1911, but the species has been slow to recover from the devastation. Some researchers believe pollutants in the water off California’s coast and the increase of commercial fishing operations have had an effect. Today, giant otters Pteronura brasiliensis, marine otters Lontra felina, South American river otters Lontra provocax, and hairy-nosed otters Lutra sumatrana are endangered. Want to help otters? Use water-efficient appliances! Water-efficient washing machines and dishwashers, low-flow showerheads, and low-flush toilets can reduce water consumption by 60 to 90 percent.

That means more clean water stays in our rivers where river otters live. You can help us bring otters back from the brink by supporting the San Diego Zoo Global Wildlife Conservancy . Together we can save and protect wildlife around the globe.

SaveSave Median life expectancy is 11.7 years YOUNG Gestation: 2 months for smaller species; up to 5 months for sea otters Number of young at birth: 1 to 5; usually 2 Weight at birth: 4.5 ounces (128 grams) for smaller species; up to 5 pounds (2.3 kilograms) for sea otters Age of maturity: 2 to 5 years SIZE Length: Largest - giant otter Pteronura brasiliensis, 4.9 to 5.9 feet (1.5 to 1.8 meters); smallest - Asian small-clawed otter Amblonyx cinereus, up to 2.9 feet (.9 meters) Weight: Heaviest - sea otter Enhyrda lutris, males up to 90 pounds (41 kilograms); lightest - Asian small-clawed otter, up to 11 pounds (5 kilograms) FUN FACTS Otters can close off their ears and nose as they dive and swim underwater. Otters are quite flexible and can easily touch their nose to their tail.

North American and European river otters have been known to share dens with beavers—but the beavers do all the building. Sea otters often hang out together in large groups called rafts. River otters can stay submerged for up to eight minutes, a relatively long period of time for an air-breathing mammal. Sea otters have the densest fur of any mammal, with about 100,000 hairs in a space about the size of a postage stamp. A Mammal Like No "Otter" Who can stay underwater for eight minutes, share a den with the local beavers, dive deep and gamely float in equal measure, and look positively adorable while doing it? ... River Otter Preservation Society B. Order----Carnivora C. Family----Mustelidae Mustelids also include skunks, badgers, weasels, minks, and sea otters. River otters make up the subfamily Lutrinae, of which there are 13 recognized species in four genera. D. Genus, species----Lutra canadensis There are eight species in the genus Lutra. Species can be distinguished by the shape and size of the hairy patch on the nose pad.

E. Fossil records The first aquatic otter appears in the fossil record 30 million years ago. Another species, Paralutra jaegeri, lived 25 million years ago and may have been an ancestral form of modern river otters. River Otter Habitat and Distribution Historically, North American river otters were widely distributed throughout Alaska, Canada, and the contiguous United States. Due to fur trapping and hunting, by the nineteenth and twentieth centuries river otter populations were greatly reduced throughout the lower 48 states except in the northwest, the upper great lakes region, New York, New England, and the states along the Atlantic and Gulf coasts. Today the North American river otter is found in reduced numbers throughout Alaska, Canada, and the contiguous United States. Other related river otter species are found in South America, Europe, and Asia. River otters depend on wetlands or other aquatic environments such as lakes, rivers, streams, and ocean bays. River otters live in burrows under roots and logs or in abandoned dens of foxes, badgers, or rabbits. A river otter's den may have one entrance below water and one above water. River otters can also be found in hollow tree trunks.

Although highly aquatic, river otters may travel several miles over land to reach another stream or lake. A river otter's home territory is usually about 5 to 48 miles along a river or stream bank. Males have larger territories than females. The territories of different otters may overlap each other. A river otter marks its territory with feces and urine, then sprays its droppings with a strong-smelling liquid from scent glands near its tail. Since different river otters use the same sites to mark their territories, the droppings seem to be a visual indicator of where an otter should sniff to determine which particular river otters have been in the area. They also rub their musky scent on logs, stones, or mounds of grass throughout their home areas. Physical Characteristics A. Size-- Male river otters average 3 to 4 ft. in length including the tail, which accounts for about one third of total body length. The largest river otter ever recorded measured 5 ft. An adult male may weigh 10 to 25 lbs. Female river otters measure over 3 ft. An adult female may weigh 12 to 18 lbs. B.

Body shape-- A river otter is long, muscular, and streamlined. Like its relative the weasel, the river otter has an upward flex in its spine which causes a hump at the hips. The spine is so flexible that an otter can bend itself nose to tail tip forwards, sideways, and backwards to form a complete circle. C. Coloration-- A river otter is brown and has a silvery sheen on its belly. D. Forelimbs-- A river otter's forelimbs have paws with well-developed webs that extend at least to the base of the last bone on each digit. The webs are covered with fur, but the toes and sole pads are furless. Front paws have well developed, non-retractive claws that are about 1/2 an inch long. The digits are very sensitive to touch. River otters use their dexterous paws for feeling for prey in muddy waters, enlarging a den in a riverbank, handling small objects, and swimming. E. Hind limbs-- Hind paws are webbed between each of the five toes. Toes are tipped with sharp, non-retractable claws.

Hind paws have small calloused pads to help give the river otter traction on slippery surfaces. The webs are covered with fur, but the toes and sole pads are furless. River otters can stand upright on their hind paws. F. Head-- Muzzle-- The river otter's muzzle is broad, flat, and short, with a blunt snout. The nose is broad, black, and rounded. A river otter closes its nostrils while under water. Vibrissae-- River otters have long stiff vibrissae (whiskers) on their muzzle. Vibrissae are 2 to 4 inches long. Vibrissae are used to locate prey and to explore the size of holes or burrows. Vibrissae are also used to detect underwater movement or obstructions by changes in water current. Teeth-- River otters have 36 sharp teeth, which they use both for catching food and aggressive behavior. Otters use their incisors to tear small pieces of flesh. Canine teeth are used to grasp slippery fish or break the tough skin of a fish. Well-developed premolars are used for crushing bones.

A river otter's brown eyes are located near the front of the skull. A river otter's ears are small, rounded, and set back on either side of its head. Ears are about 3/4 of an inch long. River otters close their ears under water. G. Tail-- A river otter's flexible, muscular tail is flattened and thick at the base, tapering to a point. The powerful tail acts as a rudder when the river otter is swimming, and as a brace when the river otter stands on its hind paws. H. Fur-- The river otter's fur is short and dense. River otters have two kinds of hair: long strong guard hairs, which form the outer layer, and finer, more dense underfur. The guard hairs form a waterproof barrier that covers and protects the underfur. The waterproof guard hairs on the back are about 1 inch long. The underfur traps a layer of air to provide insulation. Underfur on the back is about 3/4 of an inch long. There are about 156,000 hairs per square inch on a river otter.

Fur insulates an otter by preventing water from penetrating the otter's skin. Senses A. Hearing-- A river otter's hearing is very acute. Hearing is more important than smell for detecting danger on land. B. Eyesight-- River otters may be able to see better under water than above water. They can change the shape of their lens to a more spherical shape to compensate for the refractive qualities of water. C. Tactile-- Paws are sensitive to touch in locating food in mud or beneath rocks. Vibrissae detect vibrations of prey's movement in the water. D. Taste-- Little is known about a river otter's sense of taste. E. Smell-- A river otter's sense of smell is of the greatest importance in locating food on land. It also alerts them to the whereabouts of other river otters, home, and danger. Adaptations for an Aquatic Environment A. Swimming-- While swimming slowly or at the surface, river otters "dog paddle" using all four legs. River otters swim as well on their backs as they do on their bellies. Webbing increases the foot area for extra push in swimming.

On the surface a river otter can swim about 6 miles per hour. Below the surface, the river otter can swim at 3 to 4 miles per hour. When swimming, the river otter uses its body and tail for steering. B. Diving-- Records indicate that one river otter was caught in a fish net that was set 60 feet deep. This is likely an exceptional depth. The average diving depth is not known. All aquatic mammals have special physiological adaptations used during a dive. These adaptations enable a river otter to conserve oxygen while it is under water. River otters, like other mammals, have a slower heartbeat while diving. When diving, blood is shunted away from tissues tolerant of low oxygen levels toward the heart, lungs, and brain, where oxygen is needed. C. Respiration-- River otters can hold their breath six to eight minutes before resurfacing. They have been known to swim 1/4 of a mile underwater before resurfacing. While swimming under frozen ponds and lakes where air is not available, river otters can breathe bubbles of air trapped against the ice. They can also exhale a breath underwater and immediately rebreathe the bubble that formed below the surface of the ice.

D. Thermoregulation-- Fur insulates an otter by preventing water from penetrating to the otter's skin. See Physical Characteristics under H A high intake is necessary to maintain a high metabolic rate, which helps an otter keep warm. River otters eat about15% to 20% of their body weight daily. See Diet and Eating Habits under B. Behavior A. Daily activity cycle-- River otters may be either diurnal (daytime) or nocturnal (nighttime) but generally more active at night. Much of a river otter's day is spent grooming its fur to spread oils from skin glands throughout its fur for waterproofing. B. Social structure-- River otters are basically solitary. The basic family group consists of a female and her young. Such families break up before the female gives birth again. Male river otters may or may not take part in the family group. There is no strong pair bond between a male and female except for several months during the breeding season. C. Social behavior-- Some river otter behavior could be described as "playful", but what we interpret as "play" is adaptive behavior that reinforces social bonds and encourages young river otters to practice their hunting and fighting techniques.

River otters slide down muddy or snowy banks headfirst with their forepaws at their sides. Upon reaching the bottom, they climb up again and repeat the slide. Juveniles chase one another in the water and tackle each other on shore. D. Tracks-- A river otter's running stride leaves tracks from 1 to 2 feet apart. Tracks can be distinctive, especially in snow, where its body may leave a trough up to 1 foot wide as the otter pushes itself along or "sleds". Foot tracks are 3 inches wide. Diet and Eating Habit A. Food preferences and resources-- River otters are active predators whose diet consists mainly of fishes. In the water, river otters also prey on frogs, snakes, turtles, salamanders, crabs, crayfish, water beetles, aquatic insects, larvae, mussels, snails, worms, and ducks. On land, river otters prey on mice, small rabbits, and ground-nesting birds and their eggs. River otters also eat some grasses, tubers, pond weeds, algae, shoots, and blueberries. If food is scarce in the winter, river otters prey on muskrats. Occasionally they eat young beavers.

River otters do not store food for the future. They do not kill more then they eat. B. Food intake-- River otters eat 15% to 20% of their body weight daily, about 3 lbs. of food. They usually don't eat much more then 1 lb. at a time. C. Methods of collecting and eating food-- River otters hunt mainly at night, usually in the water. A mother river otter will hunt with her young. She may also join in the hunt with other females and, in the the breeding season, with males. A river otter catches a fish by waiting just above the water surface. When it locates a fish, it glides into the water and after a brief chase, catches the fish with its teeth. In shallow water, a river otter drives fish into inlets by slapping the water with its tail. It may corner fish to make them easy prey. At times several river otters hunt cooperatively to drive fish together. River otters eat small fish 3 to 5 inches long. Occasionally they catch larger fish of 4 to 5 lbs., but not often. The larger fish are stronger, faster, and harder to catch.

Smaller fish are more abundant and easier to catch. River otters usually bring their fish out on a rock, tear off the scales, and eat the fish headfirst. They may consume their food in the water. River otters grab ducks by the legs and pull them under water. River otters also take ducks wounded or killed by hunters before the ducks are retrieved. River otters regurgitate fish bones and scales. Reproduction A. Sexual maturity-- Female river otters reach sexual maturity at about two years of age. Mature female river otters usually go into estrus ( in heat ) in the first few months of the year. Males are not usually sexually mature until five to seven years of age. B. Mating activity-- The peak breeding season is March and April, when river otters travel more often and leave many scent markings to mark their territory. River otters become territorial during the breeding season. Males will sometimes fight, competing for mates, if mutual avoidance does not work. One male will mate with several females. Young females coming into their first estrus are usually the first to breed. The older females usually rebreed within a day or so after giving birth. Mating activity usually takes place in the water.

The male, swimming up behind the female, seizes her by the neck with his teeth and bends his body down around and under her tail. When breeding takes place on land, the male curls up and wraps around the female. Mating lasts 15 to 20 minutes. Birth and Care of Young A. Gestation-- The total gestation period is approximately 9 1/2 to 10 months. The maximum total gestation period recorded was 12 1/2 months and the minimum 9 1/2 months. Gestation includes a period during which the embryo remains undeveloped. This holding period is called delayed implantation. The fertilized egg divides into a hollow ball of cells one layer thick ( a blastula ), stops growing and lies freely in the uterus for an undetermined length of time. The blastula then implants in the uterine wall and continues to develop. Delayed implantation assures that the pup is born during the best time of the year for survival and allows the female to get into good physical condition and to use her energy for nursing her newborn pups. The actual embryonic development is about two months. B. Birth seasons-- River otter pups are born between February and April. C.

Frequency of birth-- A female river otter may bear a litter each year. The average litter of river otters is two to four. On rare occasions there will be five. D. Pupping-- Female river otters choose a snug den for the birth of their young. They use muskrat houses and woodchuck burrows close to the water. A mother will also pup in cavities under a stream bank, in hollow logs, or in openings under a tangle of roots along river banks. The mother chooses a den where there is an abundant food supply nearby to minimize the time pups are left alone while she goes hunting. The female river otter drives the male away from the den at birthing time. The male may travel away or may stay near a female's den. After six to eight weeks the male river otter may rejoin a female and her pups. The female is rebred by any male within the area shortly after birth when she ventures from the den in search of food. E. Pup at birth-- A river otter pup is 7 to 8 inches long and weighs 4 to 5 oz. River otter pups are born toothless, blind, and helpless.

A pup's black, silky fur is not waterproof. River otter pups spend most of their time either suckling or sleeping. F. Care of young-- Nursing-- Mother river otters nurse their pups. Otters' milk is more than 24% fat and 11% protein. A female river otter has four nipples on her abdomen just forward of the hind paws. When hungry, a pup crawls up on its belly in search of her nipples, twittering softly until it locates them. Suckling vigorously, the pup wags its tail from side to side and kneads its mother's belly with its front paws. Pups are weaned at about three to four months. A mother river otter warms the pup by curling completely around it, putting her head in the center of this circle. If the young are weaned and the mother is killed, the male river otter may raise and protect the pups. G. Pup development-- Young river otters grow rapidly. At one week of age they weigh about 6oz. and by ten days their weight increases to about 1 lb. At five weeks the pups' eyes open and they begin to interact with one another.

Pups begin to acquire the waterproof coat of an adult and shed their baby fur at five weeks. At two months the pup and family leave the den to explore their home range. Pups begin learning to swim at about two months. The mother encourages her pup into the water by swimming around and calling out to it. Once in the water, the pup holds onto the mother's fur. The mother swims underwater, forcing the pup to swim. The mother may also grab the pup by the scruff of the neck and carry or throw it into the water. When first placed in the water pups have difficulty staying upright, but after a few minutes they can swim on their own. Young river otters learn how to hunt by mimicking their parents. At first they catch only slow-moving prey like snails and worms but soon catch fish. Young river otters remain with their mother throughout their first winter. Pups are independent before the mother gives birth again. Pups reach adult size after two years. Communication River otters are easily recognized by their staccato, "chuckle". When anxious, river otters utter a hissing sound or a yelp. When threatened, the sound is a deep, nasal growl or a piercing scream.

A twittering sound is used as a companionship call. The pups in a den peep like chicks. The begging and alarm calls of pups and the mating calls of adults resemble soft whistles. A one-syllable chirp occurs as a contact call that carries quite a distance. B. Scent markings-- River otters use urine and a musky scent from scent glands to communicate with other river otters. Scent markings may provide otters with important information such as individual identity of the animal that produced the scent, its age, sex, breeding condition, and territory. The scent of a river otter's spray is very strong and can be detected near the deposition site for several weeks. Longevity and Causes of Death A. Longevity--

Question: What is a male otter called?
Answer: Dog