Amazing and Incredible

Wednesday 16 October 2019

The Venomous Blue-ringed Octopus

Blue-ringed Octopus Species

There are about at least ten species of the tiny blue-ringed octopus, which ironically for their size, are the deadliest of all cephalopods, but only four have been formally named. All these are inhabitants of Asian-pacific waters. The common name comes from bright blue rings that appear when they are alarmed or attacked. These four species are as below.

1. Greater blue-ringed octopus (Hapalochlaena lunulata) is restricted to the tropical western Pacific Ocean including Papua New Guinea, Solomon Islands, the Philippines, and Indonesia.

2. Southern blue-ringed octopus or lesser blue-ringed octopus (Hapalochlaena maculosa) is Maximum size 20 cm across arms, body length 12 cm, found along the coastline of south Western Australia to eastern Victoria, including Tasmania.

3. Blue-lined octopus (Hapalochlaena fasciata) appear as lines, instead of rings on the body; occurs chiefly along the coastline of eastern Australia to Victoria.

4. Hapalochlaena nierstraszi

The rare occurrence of the Blue-ring Octopus apprises us about the importance of this Octopus in relation to its venomous nature and importance from the medical angle. Because the medical and psychological researchers are interested in the tetrodotoxin neurotoxin found in its venom for its aphrodisiac effect and its ability to block voltage-sodium channels.

Morphometric Characteristics and Habitats

The blue-ringed octopus is one of the jewels of the ocean. It has vivid blue rings visible over the body when hunting, courting or alarmed. They are normally grown at a length of 12 to 20 cm. They are considered as one of the world's most venomous marine animals.

When this octopus is agitated, the brown patches darken dramatically, and iridescent blue rings or clumps of rings appear and pulsate within the maculae. Typically, around 50 to 60 blue rings cover the dorsal and lateral surface of the mantle. They are frequently shallow rocky reefs in the intertidal and subtidal zones, avoiding surf conditions.

Diet

They eat small crabs, hermit crabs, and shrimp exoskeleton and may bite attackers including humans if provoked. They also take advantage of small injured fish and seizing it with its arms and pulling into the mouth. The octopus uses its beak to release its venom paralyzes the muscles essential for movement, which effectively kills the prey.

Blue-ringed Octopus Life Cycle

Blue-ringed octopus females lay only one clutch of 50 to 100 eggs in their whole life. The eggs are laid then they are incubated underneath are the female arms for approximately six months. Thus, during this process, she will not eat and dies after egg hatch. Although the small size and relatively docile in nature, its venom is powerful enough to kill anyone even human is not safe from him.

Most species of blue-ringed octopuses live less than two years, reaching sexual maturity at four months. The newly hatched juveniles feed on the yolk sac until about four weeks of age when as juveniles they begin attacking live crabs. Observational studies indicate that venom is active even at an early age.

The blue-ringed octopus spends much of its life cycle hiding camouflage patterns in cervices amongst the rocks, inside seashells, and discarded bottles, and stones in the shallow water. Moreover, like all octopuses, it can change its shape with no trouble. This helps it to squeeze into crevices much smaller than itself.

This is also helping in safeguarding the octopus from predators. In common with other octopus swims by expelling water from its funnel in a form of jet propulsion. If the blue-ringed Octopus loses an arm, that he can regenerate it within 6 weeks. Hence, it has regeneration power.

Poison

The powerful venom is a neurotoxin called tetrodotoxin. It has also found him in pufferfish and is ten thousand more toxic than cyanide. It infected the toxin using its beak, causing motor paralysis and respiratory arrest within a minute and leading to cardiac arrest due to lack of oxygen.

It carries enough venom to kill 26 adult humans within a minute. Their bites though are tiny and often painless, with many victims not realizing that they have been envenomated until respiratory depression and paralyzing start to set in.

Clinical Symptoms of Blue-ringed Octopus Bite

The symptoms of a bite are respiratory arrest which can occur within a minute as the toxin blocks nerve transmission. Other symptoms include vomiting, muscle weakness, and paralysis of respiratory muscles. Victims are fully awake until a lack of oxygen, from the inability to breathe leads to unconsciousness.

Positive Values of Blue-ring Octopus venom:

Although another Octopodidae is used from biomedical research, behavioral research and as a gourmet food source, Hapalochlaena sp. Are too small and too dangerous for many of these uses.

Medical and psychological researchers are interested in the tetrodotoxin neurotoxin found in its venom for its aphrodisiac effect and its ability to block voltage-sodium channels.

So, an action potential in neurons is inhibited or reduced. They also have value as an unusual luxury item. As strange as it may seem an individual H. lunulate was sold at an expensive value.

Negative Values of Blue-ring Octopus venom:

Poison from Hepalochlacna sp. Has proven to be fatal to humans particularly for young children. There is no anti-venom for this poison. Of the several human fatalities attributed to this potent species. All have involved the animal being picked up. The bite itself may not even be felt. Five minutes or so later, however, the victim may complain of dizziness and increasing difficulty in breathing.

The powerful venom acts on the victim’s voluntary muscles, paralyzing the muscles, required for body movement and breathing. Artificial respiration is necessary to maintain life. The poison gradually wears off after 24 hours apparently leaving no side effects. Moreover, compression immobilization bandaging is used for envenomation’s where a large amount of venom is placed in one area. If any human survives the first 24 hours normally recover from potent venom.

To function as an aposematic warning display, the display colors must be within the limits of the visual system of the relevant predator species. Thus, the peak reflectance of the blue-ring lies within the range of mid and long wavelength. It is penetrating opsins of likely marine vertebrate and invertebrate predators, together with cetaceans, birds, pinnipeds, teleost fishes and cephalopods.

Besides, the blue-green part of the visible spectrum is the most protuberant ambient underwater light field. Hence the iridescence is spectrally well-tuned to be maximally visible. Also, the peak reflectance of the iridescence also resembles the spectral absorbance of some of the recognized cephalopod visual pigments.

Read More – Golden Chains of Laburnum / The Snapping Turtles (Chelydra serpentina)

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Sunday 6 October 2019

Wildlife Values of Conservation Trees and Shrubs

SHRUBS

CARAGANA (SIBERIAN PEASHRUB) (Caragana arborescens): Used for nesting by several songbirds and the seeds are occasionally eaten. Not a preferred food for browsing animals. It provides good cover. (Introduced from Siberia).

COTONEASTER (Cotoneaster acutifolia): Provides roosting and loafing cover for numerous songbirds and game birds, and some utilize the fruits for food (esp. catbird, mockingbird, and purple finch). Not a preferred browse for animals. (Introduced from northern China).

HONEYSUCKLE (Lonicera tatarica): Provides fruit, which is eaten by several songbirds. It also provides some cover for both bird and animal species but has little value as a browse source. Preferred nesting site for many songbirds. Prefers open, moist areas; good in fencerows. It provides food for songbirds, rabbits, quail, and turkeys. (Introduced from southern Siberia).

CHOKECHERRY (Prunus virginiana): All parts of the plant have some benefit to wildlife for winter food, but most important during summer and fall. Among the most important plants for wildlife cover and food. The shrubby, thicket-forming growth provides cover for songbird nesting, loafing, and roosting, and animal loafing and bedding. The fruit and foliage are relished by a great number of wildlife species, including songbirds, upland game birds, rodents and other small mammals, bears, and whitetail and mule deer. (Native to most of North America).

COMMON LILAC (Syringa vulgaris): Because of root suckers, it provides high-quality cover for numerous species of birds and animals. Little value for fruit or browses. (Introduced from Eastern Europe).

NATIVE (AMERICAN) PLUM (Prunus americana): Highly important as wildlife cover and food. The thorny, suckering growth when protected forms a thicket valuable for bird nesting, loafing, and roosting, and animal loafing and bedding. Twigs and foliage provide a highly preferred browse for whitetail and mule deer. Foxes are chief consumers of fruit. (Native over eastern two-thirds of central North America, including eastern Colorado).

SKUNKBUSH SUMAC (QUAILBUSH) (Rhus trilobata): Prefers moist, sunny, open areas, but will grow in dry locations. Good in the fence row, along roads, and canal/stream edges. Important fall and winter food for songbirds, woodpeckers, and deer. Emergency winter food for game birds. Fruit and buds are stapled food for sharp-tailed grouse. A good source of vitamin A. Bark and twigs eaten by rabbits, rodents, and deer. Provides high quality roosting and loafing cover for many bird species and is a preferred nest site for many thicket-nesting birds. (Native to western North America).

WESTERN SAND CHERRY (BESSEY CHERRY) (Prunus besseyi): Provides preferred fruit for numerous songbirds. Growth form creates good roosting and loafing cover for songbirds and game birds, and nesting cover for songbirds. Occasionally browsed by deer. Short-lived; notable decline in vigor after 5 years. (Native to northern Great Plains, including northeastern Colorado).

NANKING CHERRY (Prunus tomentosa): Utilized by a few songbirds as nesting cover and produces a fruit that is relished by many songbirds. Preferred browse for rabbits, other rodents, white-tailed deer, and mule deer. (Introduced, native to China and Japan).

EUROPEAN SAGE (Artemesia abrotanum): Good in semi-arid sites. Better for cover than for food, but is eaten by antelope, mule deer, and small mammals.

WOODS ROSE (Rosa woodsii): Good in fencerows, along roads, and borders for windbreaks. Especially good food during bad winter weather. Hips high in vitamin C. Important food to upland game birds and deer and excellent nesting/escape cover for songbirds and game birds. (Native to much of North America).

SILVER BUFFALOBERRY (Shepherdia argentea): Will sucker like native plum and form thickets. Thorny thickets create an ideal cover for numerous bird and animal species. Preferred nesting site for many songbirds. Some birds eat the fruit although it is not relished by a wide variety of species. (Native to northwestern North America, including Colorado).

GOLDEN CURRANT (Ribes aureum): Good cover for birds and small mammals. Good palatability to game animals. Preferred roosting, loafing, or nesting cover for several songbirds and has general use by many birds for food. A preferred browse of mule deer. (Native to western North America).

SASKATOON SERVICEBERRY (JUNEBERRY) (Amelanchier alnifolia): Will grow in dry, rocky areas. A high-quality plant for wildlife cover and food. Songbirds and game birds seek the sweet, juicy berries in early summer. Squirrels, rodents, and bears also eat fruit. Whitetail and mule deer browse twigs and foliage extensively. The shrubby growth provides cover for bird nesting, loafing, and roosting, and animal loafing and bedding. (Native to western North America).

FOURWING SALTBUSH (Atriplex canescens): Provides cover and food for songbirds and small mammals as well as forage for antelope, whitetail deer, and mule deer. A San Miguel County landowner reports that elk heavily utilizes the four-wing saltbush there as winter and spring browse, a large herd removing as much as a meter’s growth over winter. (Native to the western U.S.)

COYOTE (SANDBAR) WILLOW (Salix exigua Nutt.): Coyote and other varieties of riparian willows are very important as browse and cover for the big game, especially in fall and winter. Also important as food and cover for birds in winter, particularly ptarmigan. Especially valuable along trout streams as shade and cover, and as a secondary food source for beaver. (Native to North America).

GAMBEL OAK (Quercus gambeli): Also called shrub oak and oak brush. Very important for mast, browse, and cover. Acorns are eaten by many species, especially jays, wild turkey, squirrels, and bears. Important winter browse and mast for deer, bighorn sheep, and elk. (Native to parts of southwestern U.S., including Colorado, and northern Mexico).

ANTELOPE BITTERBRUSH (Purshia tridentata): Palatable and a very important browse for deer, elk, antelope, and livestock, except horses. Other species, such as rabbits and grouse, also utilize. (Native to western North America).

TRUE MOUNTAIN MAHOGANY (Cercocarpus montanus): Very important browse species for all big game ungulates and livestock. Provides cover and food (seeds) for small game birds and mammals. (Native to western North America).

NEW MEXICO FORESTIERA (Forestiera neomexicana): Taken sparingly by deer, almost unpalatable to livestock. Fruits are eaten by quail and songbirds. (Native to southwestern U.S., including southwest Colorado).

DECIDUOUS TREES

GREEN ASH (Fraxinus pennsylvanica var. lanceolata): Most common on prairie, preferring moist areas. Of moderate importance to wildlife. The winged seeds (samaras) are eaten by several birds and mammals including wild turkey and rodents. Whitetail and mule deer browse the twigs and foliage. The biggest benefit is shade. (Native to eastern North America, including watercourses in eastern Colorado).

HONEYLOCUST (Gleditsia triacanthos var. inermis): Has limited wildlife use but provides some songbird cover and is eaten by cottontail rabbit, squirrels, and deer. (Native to central U.S.)

BLACK LOCUST (Robinia pseudoacacia): Seed is eaten by bobwhite quail and squirrel. (Native to parts of the eastern half of U.S.)

SIBERIAN (CHINESE) ELM (Ulmus pumila): Little value as a food source for game birds or mammals. Not sought by birds or mammals as a source of quality browse or cover, although it is used for nesting (esp. English sparrows and orioles). Seeds are eaten by songbirds, game birds, and rodents. (Introduced, native to northern China and eastern Siberia).

Wildlife Values of Conservation Trees and Shrubs

COTTONWOOD: HYBRID AND NARROWLEAF (Populus deltoides var. noreaster, Populus angustifolia): Need moist areas. Buds/catkins are good food in winter and early spring. Bark, twigs, and leaves are eaten by rodents, rabbits, deer, beaver, and porcupines. Provide forage for browsing wildlife such as whitetail and mule deer up through the sapling stage. Provide important nesting and roosting habitat for various species of birds. (Hybrid native to eastern North America, narrow-leaf native to Rocky Mountain region of North America).

GOLDEN WILLOW (Salix alba var. vitellina): Moist, fertile sites needed. Good browse food for the big game, rabbits, and beaver. It provides forage for browsing wildlife such as whitetail and mule deer through the sapling stage. It provides important nesting and roosting habitat for various species of birds. (Introduced, native to Europe, North Africa, and central Asia).

HACKBERRY (Celtis occidentalis): Fruit important winter food for songbirds (esp. waxwings, sapsuckers, mockingbirds, and robins). Important for shade. About 45 wildlife species eat fruit, and deer browse on twigs and leaves. (Native to eastern United States, including plains of eastern Colorado).

RUSSIAN OLIVE (Elaeagnus angustifolia): Spreads quite well on its own (birds and deer distribute seed). Tolerates alkaline soil and hardy during drought. Berries are a choice food of many birds and an important winter food for waxwings, grosbeaks, and robins. Not a preferred food for browsing animals. Fairly low overall wildlife value - has been overrated in the past. Tends to take over riparian areas, so avoid planting in. (Introduced from Eurasia).

LOMBARDY POPLAR (Populus nigra var. italica): Limited wildlife value, some songbirds use for nesting (especially English sparrows). (Introduced from Europe).

ASPEN (Populus tremuloides): Very important browse in many areas for snowshoe hare, deer, and elk. Deer avidly takes fallen leaves in fall and early winter. Important food and building material for beaver. Grouse depend on buds for winter food. (Native to North America).

BUR OAK (Quercus macrocarpa): Very important to wildlife. Acorns are very (possibly most) important wildlife food, especially in winter. Almost 100 wildlife species use oak; quail, turkey, deer, bear, and squirrels are especially avid acorn eaters. Also, excellent wildlife cover. (Native to mid-western and northeastern U.S., and southeastern Canada).

CONIFEROUS TREES (EVERGREENS)

PINE: AUSTRIAN, SCOTCH, PONDEROSA, PINON, LODGEPOLE, LIMBER, & BRISTLECONE (Pinus nigra, P. sylvestris, P. ponderosa, P. edulis, P. contorta, P. flexilis, P. aristata): Pines are nearly as important as oaks. All parts of the tree are used and/or eaten. Pine seeds are especially important for food. Bark harbors insects that woodpeckers, sapsuckers, and nuthatches eat. (Austrian and Scotch pine introduced from Europe; Ponderosa and lodgepole native to western North America; piñon native to western U.S. and northern Mexico; limber and bristlecone native to the western U.S.)

JUNIPER: EASTERN REDCEDAR & ROCKY MOUNTAIN (Juniperus virginiana, J. scopulorum): Some food value to songbirds. Important escape and nesting cover for songbirds and game birds. Use caution near apple trees, as juniper is the alternate host for apple rust. (Eastern redcedar native to central and eastern U.S., Rocky Mountain juniper native to the western U.S. and Canada).

SPRUCE: COLORADO BLUE & ENGELMANN (Picea pungens, P. engelmannii): Little food value. Provide excellent nesting, roosting, and winter cover for numerous small birds. Deer will browse on blue spruce although it is not a preferred forage plant. (Blue spruce native to Rocky Mountains of U.S.; Engelmann spruce native to the western U.S. and Canada).

DOUGLAS-FIR (Pseudotsuga menziesii): Seeds used by squirrels, rabbits, and other rodents. (Native to western North America).

WHITE FIR (Abies concolor): Prefer cool, moist sites. Moderate wildlife importance mostly used for cover by mammals and game birds. Used for roosting and nesting by songbirds, seeds eaten by squirrels. (Native to western U.S. and Mexico).

Read More – The Snapping Turtles (Chelydra serpentina)

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Thursday 3 October 2019

Red Fox Facts (Vulpes vulpes)

Unlike the more social wolves, foxes and coyotes tend to hunt alone, although coyotes may hunt larger prey in pairs. Foxes and coyotes are primarily carnivorous, preying predominantly on small mammals. But they also may eat insects, fruits, berries, seeds, and nuts. Foxes are found throughout most of the United States and Canada, including the arctic, as are coyotes except for the southeastern United States. Foxes and coyotes are active mainly at night.

Red foxes (Vulpes vulpes) are present throughout the United States and Canada except in the southeast, extreme southwest, and parts of the central states. Red fox preys extensively on mice and voles but also feed on other small mammals, insects, hares, game birds, poultry, and occasionally seeds, berries, and fruits.

Twelve subspecies are recognized in North America. The dog-sized red fox has a body of about 56 to 63 cm in length, with a 35 to 41 cm tail. They weigh from 3 to 7 kg, with the males usually outweighing the females by about 1 kg.

Habitat

As the most widely distributed carnivore in the world, the red fox can live in habitats ranging from arctic areas to temperate deserts. Red foxes utilize many types of habitat cropland, rolling farmland, brush, pastures, hardwood stands, and coniferous forests. They prefer areas with broken and diverse upland habitats such as occur in most agricultural areas. They are rare or absent from continuous stands of pine forests in the southeast, moist conifer forests along the Pacific coast, and semiarid grasslands and deserts.

Food Habits

The red fox feeds on both animal and plant material, mostly small mammals, birds, insects, and fruit. Meadow voles are a major food in most areas of North America. However, other common prey includes mice and rabbits. Game birds (e.g., ring-necked pheasant and ruffed grouse) and waterfowl are seasonally important prey in some areas.

Plant material is most common in red fox diets in summer and fall when fruits, berries, and nuts become available. Red foxes often cache food in a hole for future use. They also are noted scavengers on carcasses or other refuse. Most activity is nocturnal and at twilight. In winter, foxes do not undergo hibernation or torpor; instead, they are active year-round. They undergo one molt per year, which usually begins in April and is finished by June. The winter coat is regrown by October or November in northern latitudes.

Breeding occurs earlier in the south than in the red fox's northern ranges. A mated pair maintains a territory throughout the year, with the male contributing more to its defense than the female. Pups are born and reared in an underground den, and the male assists the female in rearing young, bringing food to the den for the pups.

Pups first emerge from the den when 4 to 5 weeks old. Once considered solitary, red foxes now are reported to exhibit more complex social habits. A fox family, the basic social unit, generally consists of a mated pair or one male and several related females. The additional females are usually nonbreeders that often help the breeding female.

Range

The home ranges of individuals from the same family overlap considerably, constituting a family territory. Territories of neighboring red fox families are largely nonoverlapping and contiguous, usually resulting in all parts of a landscape being occupied by foxes. Territory sizes range from less than 50 to over 3,000 ha. Territories in urban areas tend to be smaller than those in rural areas.

Adults visit most parts of their territory on a regular basis; however, they tend to concentrate their activities near to their dens, preferred hunting areas, abundant food supplies, and resting areas. Territory boundaries often conform to physical landscape features such as well-traveled roads and streams.

Territory defense is primarily by nonaggressive mechanisms involving urine scent-marking and avoidance behaviors. Scent marking occurs throughout the territory; there is little patrolling of territory boundaries. Each fox or family usually has a main underground den and one or more other burrows within the home range.

Most dens are abandoned burrows of other species e.g., woodchucks, badgers. Tunnels are up to 10 m in length and lead to a chamber 1 to 3 m below the surface. Pup-rearing dens are the focal point of fox activity during spring and early summer. Foxes have some rest sites and usually forage away from the den.

One red fox family per 100 to 1,000 ha is typical. Red foxes have larger home ranges where population densities are low and in poorer habitats. Most young foxes, especially males, disperse before the age of 1, usually from September to March, with peaks in dispersal in October and November.

Foxes usually produce pups their first year, except in extremely high-density areas and in some years in northern portions of their range where they may delay breeding until the next season. Litter size generally averages four to six pups. The pups leave the den about 1 month after birth, and they are weaned by about 8 to 10 weeks of age.

Red foxes incur high mortality rates as a result of the shooting, trapping, disease, and accidents at roadkill. Two factors that tend to limit red fox abundance are competition with other canids, especially coyotes, and seasonal limits on food availability. Fecundity is higher in areas of high mortality and low population densities.

Similar Species

The arctic fox (Alopexlagopus) is smaller than the red fox (body length approximately 51 cm; weight 3.2 to 6.7 kg) and is restricted in its distribution to the arctic, found in the United States only in Alaska. This species primarily scavenges for food but also eats lemmings, hares, birds, and eggs as well as berries in season.

The swift fox (Vulpes velox) is smaller than the red fox (body length 38 to 51 cm; weight 1.8 to 2.7 kg) and inhabits the deserts and plains of the southwest and the central United States. It dens in ground burrows and feeds on small mammals and insects.

The kit fox (Vulpes macrotis) is similar in size to the swift fox and is considered by some to be the same species, although it has noticeably larger ears. It inhabits the southwestern United States and prefers open, level, sandy areas, and low desert vegetation. It feeds on small mammals and insects.

The gray fox (Urocyon cinereoargenteus) is similar in size (body length 53 to 74 cm; weight 3.2 to 5.8 kg) to the red fox and ranges over most of the United States except the northwest and northern prairies. It is inhabiting chaparral, open forests, and rimrock regions. Secretive and nocturnal, gray foxes will climb trees to evade enemies. They feed primarily on small mammals but also eat insects, fruits, acorns, birds, and eggs.

The coyote (Canis latrans) is much larger (body length 81 to 94 cm; weight 9 to 22 kg) than the red fox and is found throughout most of the United States (except possibly eastern), western Canada, and Alaska. It inhabits prairies, open woodlands, brushy and boulder-strewn areas, and dens in the ground. Coyotes share some feeding habits with the red fox but also scavenge and hunt larger prey in pairs.

Read More – The Snapping Turtles (Chelydra serpentina)

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Saturday 28 September 2019

The Northern River Otter (Lutra canadensis)

River Otter Facts

Mustelids have long, slender bodies, short legs, and anal scent glands. Throughout the family, the male is usually larger than the female. The more terrestrial species of this family occupy various habitats and feed primarily on small mammals and birds. Mustelids that live around lakes and streams feed primarily on aquatic species such as fish, frogs, and invertebrates.

The northern river otter (Lutra canadensis) historically lived in or near lakes, marshes, streams, and seashores throughout much of the North American continent. Currently, many populations along the coastal United States and Canada are stable or increasing, but this species is rare or extirpated throughout much of the midwestern United States.

The river otter dens in banks and hollow logs. Individuals range over large areas daily, feeding primarily on fish. Although otters have few natural predators, while on land, they may be taken by coyotes, fox, or dogs. Otters clean themselves frequently by rubbing and rolling in any dry surface.

Otters appear to undergo bradycardia while submerged and can stay underwater for up to 4 minutes. Because of its piscivorous diet and high trophic level, the river otter is a noteworthy indicator of bioaccumulative pollution in aquatic ecosystems.

Body Size

River otters measure 66 to 76 cm with a 30 to 43 cm tail. Sexual dimorphism in size is seen among all subspecies, and adult males (5 to 10 kg) outweigh females (4 to 7 kg) by approximately 17 percent. Full adult weight generally is not attained until sexual maturity after 2 years of age.

Along the Pacific Coast, there is some evidence that size decreases from north to south. The basal metabolic rate of otters and other mustelids weighing 1 kg or more. The Free-living metabolic rates would be expected to be three to five times higher.

Habitat

Almost exclusively aquatic, the river otter is found in freshwater, estuarine, and some marine environments all the way from coastal areas to mountain lakes. They are found primarily in food-rich coastal areas, such as the lower portions of streams and rivers, estuaries, nonpolluted waterways, the lakes and tributaries that feed rivers, and areas showing little human impact.

River Otter Diet

Otters usually are active in the evening and from dawn to midmorning, although they can be active any time of day. The bulk of the river otter's diet is fish; however, otters are opportunistic and will feed on a variety of prey depending on availability and ease of capture. River otters take different fish species according to their availability and how well the fish can escape capture.

Depending on availability, otters also may consume crustaceans (especially crayfish), aquatic insects (e.g., stonefly nymphs, aquatic beetles), amphibians, insects, birds (e.g., ducks), mammals (e.g., young beavers), and turtles.

River otters consume more waterfowl in the northerly latitudes than in the south, probably because of the ease of capturing the waterfowl during their molt in the north. Otters probe the bottoms of ponds or streams for invertebrates and may ingest mud or other debris in the process. Otters in captivity required 700-900 g of food daily.

Temperature Regulation and molt

Seasonal patterns in otters are not well understood. Otters are active throughout the year. The most intense activity levels during the winter. They undergo a gradual molt in spring and fall.

Breeding activities and social organization

Adult males are usually solitary; an adult female and two or three pups make up a typical family group. River otters breed in late winter or early spring over a period of 3 months or more. Birth of a litter follows mating by about 1 year; however, implantation is delayed for approximately 10 months, and active gestation lasts only 2 months.

Newborn otters are born blind but fully furred and depend on their mother for milk until 3 to 5 months of age. Family groups disperse about 3 months after the pups are weaned. Home range and resources. The river otter's home range encompasses the area needed for foraging and reproduction.

The shape of the home range varies by habitat type; for example, near rivers or coastal areas, it may be a long strip along the shoreline. But in marshes or areas with many small streams, the home range may resemble a polygon.

All parts of a home range are not used equally; instead, several activity centers may be interconnected by a stream or coast. Food has the greatest influence on habitat use, but adequate shelter in the form of temporary dens and resting sites also plays a role. River otters use dens dug by other animals or natural shelters such as hollow logs, logjams, or drift piles.

River otters appear to prefer flowing water habitats over more stationary water (e.g., lakes, ponds). River otters maintain distinct territories within their home ranges: females maintain a feeding area for their families, males for breeding purposes.

Individuals tend to avoid confrontation through mutual avoidance. Home ranges are most restricted for lactating females. Adult and subadult males have larger, more variable home ranges than females.

River otter populations show variable spacing in relation to prey density and habitat. This characteristic, along with their secretive habits and use of several den sites, makes it difficult to estimate river otter populations. Population density of otters often is expressed in terms of number per kilometer of waterway or coastline because of their dependence on aquatic habitats. Densities between one otter every kilometer to one otter every 10 km of river or shoreline are typical.

Otters generally are not sexually mature until 2 years of age. Adult females appear to reproduce yearly in Oregon (based on a pregnancy rate of almost 100 percent. They breed every other year in Alabama and Georgia. Litters usually consist of two to three pups, although litters as large as six pups occur. As adults, river otter mortality rates are low, between 15 and 30 percent per year.

Similar Species

The sea otter (Enhy dralutris) is 76 to 91 cm body and 28 to 33 cm tail; weight 13 to 38 kg, inhabits kelp beds and rocky shores from the Aleutian Islands to California. Its diet includes fish, abalones, sea urchins, and other marine animals.

Read More – The Snapping Turtles (Chelydra serpentina)

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