Water vole — it is an amphibious carnivorous rodent. It displays many adaptations related to foraging in the water and digging along streams, rivers and lakes. One of the smallest species is the South American fish-eating rat, with a body length of 10 to 12 cm and a tail of about the same length. The golden-bellied water vole from Australia and New Guinea is the largest, with a body length of 20 to 39 cm and a shorter tail (20 to 33 cm).
Origin of the species and description
Although all water voles are members of the Muridae family, they belong to two distinct subfamilies . The genera Hydromys, Crossomys, and Colomys are classified in the subfamily Murinae (Old World mice and rats), while the American species are members of the subfamily Sigmodontinae (New World mice and rats).
In the Asian tropics or in non-tropical latitudes, water voles do not exist. The ecological niche of water voles there is occupied by carnivorous amphibious shrews and moles. European water voles (Genus Arvicola) are also sometimes called water rats. Water voles are believed to have originated in New Guinea. Well adapted to aquatic life thanks to its webbed hind feet and waterproof coat, the water vole is distinguished by its large size and long, white-tipped tail.
Video: Water vole
Key features that help distinguish the water vole from other rodents include:
- front teeth: one pair of distinctive chisel-like incisors with hard yellow enamel on the anterior surfaces;
- head: flattened head, long blunt nose, with lots of whiskers, small eyes;
- ears: noticeably small ears;
- feet: webbed hind feet;
- tail: thick, with a white tip;
- colour: variable. From almost black, gray with brown or white to orange. Thick, soft, waterproof fur.
Appearance & Features
Many of us have had the unpleasant experience of hearing domestic rats nibble at night: an unwanted wild animal that can spread disease. In contrast, the Australian water vole, despite belonging to the same family, is an attractive native animal.
The water vole is a distinctive rodent that specializes in aquatic life. This is a relatively large rodent (its body length is about 30 cm, the length of the tail is up to 40 cm, and the weight is about 700 g) with wide, partially webbed hind legs, water-repellent long and thick fur and many sensitive whiskers.
The long, wide hind feet of the water vole are lined with stiff hairs and have bald soles with prominent webbing between the toes. They use their large, partially webbed hind feet as paddles while their thick tail acts as a rudder. The body is streamlined and its color varies from gray to almost black on the back and from white to orange on the belly. As animals age, the dorsal (back or upper side) fur changes to a gray-brown color and may be spotted with white.
The tail is thick, usually heavily furred, and in some species the hairs form a keel along the underside. The skull of the water vole is large and elongated. The eyes are small, the nostrils may be closed to keep water out, and the outer part of the ears is either small and fluffy or missing. In addition to their obvious need for water, they are habitat generalists capable of occupying a range of aquatic environments, both natural and artificial, fresh, brackish and salty. They tend to avoid high energy currents, preferring slow motion or calm water.
Where does the water vole live?
Water the vole is commonly found in permanent fresh or brackish waters, including freshwater lakes, streams, swamps, dams, and city rivers. Living near freshwater lakes, estuaries and rivers, as well as coastal mangrove swamps, it is tolerant of heavily polluted aquatic habitats.
This species occupies a wide variety of freshwater habitats, from subalpine streams and other inland waterways to lakes, swamps and farm dams. The population may exist in drainage swamps, although the water vole seems to be much less common along the riverbed itself. Animals can adapt to the conditions of urban areas and are one of the few native species that have benefited, at least in some areas, from human activities.
Water voles of the genus Hydromys live in the mountains and coastal lowlands of Australia, New Guinea, and some nearby islands. The waterless rat (Crossomys moncktoni) lives in the mountains of eastern New Guinea, where it prefers cold fast streams surrounded by rainforest or grass.
The African water vole is also found along rainforest-fringed streams. The 11 Western Hemisphere water voles are found in southern Mexico and South America, where they typically live along rainforest streams from sea level upwards to mountain pastures above the tree line.
Now you know where the water vole is found. Let's see what it eats.
What does the water vole eat?
Water voles are carnivores, and although they catch most of their prey in shallow water close to coastlines, they are also adept at hunting on land. They are predominantly carnivorous and their diet varies by location.
Prey may include crayfish, aquatic invertebrates, fish, mussels, birds (including poultry), small mammals, frogs, and reptiles (including small turtles). They have also been seen near urban waterways when hunting black rats. Water voles can also eat carrion, food scraps, the occasional plant, and have been observed to steal food from pet bowls.
Water voles — smart animals. They take the mussels out of the water and leave them in the sun to open before eating. Researchers have found that they are very careful with traps, and if they are caught, they do not make the same mistake twice. If they are accidentally caught in nylon traps, they are more likely to start chewing on them. However, like turtles and platypuses, water voles can drown if caught in a fish trap.
Water voles are generally shy and are not often seen eating, however, there is one sign that indicates their presence, — it is their habit to dine at the “table”. After the prey is captured, it is carried to a convenient feeding area such as an exposed tree root, stone or log. Discarded crayfish and mussel shells on such a “table”, or eaten fish scattered around a pond, can be a good sign that a water vole lives nearby.
Fun fact: Water voles love gather food and then dine at the “meal table.”
Twilight is probably the best time to see water voles, as they are usually most active after sunset, but these animals are unique among rodents because of their likely spontaneous daytime feeding.
Character and lifestyle features
Water Mouse — ground nocturnal rodent. Constructed nesting mounds and natural or artificial depressions located near or above the high tide mark are used for shelter during the day and between tidal cycles. Artificial structures can also be used for shelter when no other suitable sites exist.
The water vole spends most of its day in burrows along the stream, but is mostly active around sunset when it comes out to feed, although it has also been known to forage during the day. It builds a grass-lined nest at the entrance to its burrow, which is usually hidden among vegetation and built at the end of tunnels on the banks of rivers and lakes.
Fun fact: Water voles' burrows are usually hidden among vegetation and built along the banks of rivers and lakes. The round entrance has a diameter of about 15 cm.
Most water voles — skilled swimmers and aggressive underwater predators, but the African water vole (Colomys goslingi) roams shallow water or sits at the water's edge with a submerged muzzle. The water vole has adapted well to life with humans. It used to be hunted for its fur, but is now a protected species in Australia and the population appears to have recovered from the effects of hunting.
However, current potential threats to the species include:
- habitat change from flood mitigation, urbanization and marsh drainage;
- predation by introduced animals such as cats, foxes and some native birds of prey;
- youngsters are also vulnerable to predation by snakes and large fish.
Photo: Water vole
Male water voles defend their territory selflessly. They leave a distinctly pungent scent to mark their land. Not only are they smelly, male water voles are quite aggressive and will vigorously defend their territory, which can lead to violent fights with enemies, sometimes resulting in the loss or injury of their tails. Water vole — a fierce hunter who prefers the roots of trees along the banks of the river as a place of regular feeding.
Little is known about the reproductive biology of this species. It is believed to breed all year round, however most breeding occurs from spring to late summer. Research has shown that social factors, individual age, and climate can also influence breeding times. Animals of mixed age and sex may share a burrow, although only one sexually active male is usually present. The burrow can also be used for several years by later generations.
Females typically breed at eight months of age and may have up to five litters, each with three to four young per year. After about a month of suckling, the cubs are weaned and should be able to fend for themselves. They become independent eight weeks after birth.
Fun fact: Water voles typically live in the wild for a maximum of 3-4 years and are mostly solitary.
It is a tough and resilient species that tolerates human encroachment and habitat modification.
Water voles' natural enemies
During the depression in the 1930s, a ban was placed on the importation of fur skins (mainly American muskrat). The water vole was seen as an ideal substitute, and the price of its pelt rose from four shillings in 1931 to ten shillings in 1941. During that time, water voles were hunted, and the decline and extinction of the local population of the species was recorded. Later, protective legislation was introduced and over time the population recovered.
Despite wild hunting in the 1930s, the distribution of water voles does not appear to have changed much since European settlement. As urban and rural land management practices continue to improve, there is hope that the habitat of this little-known Australian aquatic predator will also improve.
The main threats to water voles today are habitat change from flood mitigation and swamp drainage, and predation by introduced animals such as cats and foxes. Juveniles are also threatened by snakes and large fish, while adult water voles can be preyed upon by birds of prey.
Population and species status
As a species, the water vole poses the least concern for conservation, although water management practices have undoubtedly changed its habitual habitat, and its current range is probably similar to that which was occupied before European settlement.
The water vole is considered a pest in irrigation areas (eg along the Murray) where it hides in canals and other water and irrigation structures, causing leakage and sometimes collapse of structures. Some sources, however, consider this damage less significant than that caused by freshwater crayfish, whose population is helped to control the water vole. However, the water vole is listed as Vulnerable in Queensland (Nature Conservation Act 1992) and nationally (Environmental Protection and Biodiversity Conservation Act 1999) is recognized as one of the top conservation priorities under the priority activity framework. Back-Track in Australia.
The water vole is mostly threatened by habitat loss, fragmentation and degradation. This has been the result of urban development, sand mining, land reclamation, swamp drainage, wildlife, recreational vehicles, polluted water discharges, and chemical pollution (runoff from agricultural and urban land, exposure to acid sulfate soils, and coastal pollution incidents). These degrading processes reduce potential foraging resources and nesting opportunities, encourage weed entry, and increase predation by wildlife (foxes, pigs, and cats).
Water vole — ground nocturnal rodent. It is found in a wide variety of aquatic habitats, typically coastal salt marshes, mangroves and adjacent freshwater wetlands in Australia. It is a good colonizer and can be expected to be a reasonable indicator of the presence of its largely aquatic prey and the general quality of the waters it normally inhabits.