These impossibly cute swimming weasels are notoriously shy which is why they may not be seen as often as their populations in the state would indicate. Department reports now show that the animals are returning to their historic range. While river otters, the otters found in Texas, may be found around the salty waters of the Texas Gulf Coast they are distinct from their much larger cohort.
Male sea otters can weigh up to 90 pounds while male river otters typically reach around 30 pounds female river otters weigh around pounds. Unlike back-floating sea otters, river otters stay belly down with most of their bodies submerged. They will also take over beaver lodges.
Several years ago, scientists surveyed beaver in Big Bend. They found that these water-loving mammals are holding their own. Thomas Simpson is a retired Texas State University biology professor. The bank burrows are an adaptation to this environment, Simpson said. Those pulse floods would sweep away a typical beaver lodge. The fur trade was a central economic venture for early Europeans in the West.
Beaver fur was prized, and tens of millions of beaver were killed. Rio Grande beaver were certainly trapped — but beaver in colder regions were thought to have thicker, more luxuriant fur. While beaver were wiped out on some northern rivers, they endured here. Found over most of the state where suitable aquatic habitat prevails. In the western part of its range it occurs in low density and local distribution, and it is absent from the Llano Estacado except for Randall County and some adjacent areas and from much of the Trans-Pecos.
Castor c. Beavers are aquatic and require water in the form of a pond, stream, lake, or river. Because of their skills in regulating water level and stream flow with dams, beavers are able to convert an unfavorable area into one that is habitable.
However, over time, their ponds tend to fill in with sediment and eventually become meadows, forcing the beavers to move to new sites. Large rivers and lakes offer suitable habitat in places where natural food and den or house sites are available, but the largest populations are on smaller bodies of water. In cold regions, beavers live in houses lodges constructed of sticks and mud. Beavers enter and leave their lodge by means of underwater tunnels, or plunge holes.
In Texas they may burrow into cut banks of streams or lakes. Burrows as long as 50 m ft. Researchers have found that this oil contains at least forty-five chemical ingredients, and humans have used the oil in making perfumes. The scented patty reveals the sex of the beaver that made it and many other messages only another beaver can understand. It serves as a chemical communication system. Unlike its northern relatives, the Texas beaver usually can move about during most of the winter season.
Although the water's surface seldom freezes around its lodge, the southern beaver still gathers and stores a cache of twigs and branches under water for winter food. Probably the most distinctive part of the beaver is its tail, which looks like a large scaly paddle.
The adult's tail is about a foot long, six or seven inches wide, and less than an inch thick. The base is covered with the same type of fur as the body, but the flat, scaly part of the tail has only a few short, bristly hairs. The tail serves as a prop on dry land, bracing the beaver as it cuts down a tree and helping the beaver sit up so it can use its front feet for various chores.
At any sign of danger the beaver slaps its flat tail on the water's surface with a loud smack, creating a big splash before it dives to safety. Some observers believe that slapping the tail in water and on land not only is a warning signal for fellow beavers, but also may be a sign of anger or an attempt to frighten away an approaching predator.
A downward thrust of the tail as the beaver submerges helps push its body under. Once underwater, the tail acts as a diving plane, determining the angle of descent. It also serves as a rudder, keeping the beaver on a straight course, especially when the animal is towing a tree or large branch.
Seldom, if ever, is the tail used for actual swimming. Large, webbed hind feet deliver the powerful strokes that push the beaver through the water. The webbing folds together ducklike as the foot is brought forward and spreads wide for the backward thrust. If the beaver is in no particular hurry, its back feet stroke at the same time, sending it forward in a smooth glide. As the forward movement slows, the feet stroke together again. But when the beaver needs to turn on the speed, it switches to alternate foot strokes.
Since each foot is six or seven inches long and spreads to a width of about six inches, each individual kick produces quite a bit of forward thrust. To further streamline its shape in the water, the beaver hugs its front legs to its chest.
The front feet are clenched into fists and serve as bumpers. These flexible front feet can be used almost like hands. Even though the beaver doesn't have thumbs, it has five fingers that are able to pick up and grip objects with ease. While the beaver is underwater, its heartbeat slows so less oxygen is needed. An extra large liver and big lungs make it possible for the beaver to store air and oxygen-rich blood for long dives. Three minutes is the beaver's usual time underwater, but it can stay down for as long as fifteen minutes.
It's not unusual for the beaver to travel as far as half a mile underwater before surfacing, especially if frightened. The beaver has several waterproofing devices that go into operation as it submerges. Valves in the ears and nostrils snap shut and membranes slide over the eyes like goggles to protect them and increase their underwater vision. Folds of skin meet tightly behind the large front teeth to seal off the mouth.
These folds of skin also prevent splinters from entering the mouth as the beaver chomps away on land or in the water. Speaking of chomping, another unmistakable feature is the beaver's large, orange buckteeth.
As with other rodents, these front teeth grow continually and are kept worn down by constant gnawing. The front surface is very hard enamel that wears slowly.
The backs are of a softer material that wears faster. This unequal wear gives the teeth a chisel-like edge, and the angle the edges form makes it possible for the beaver to sharpen them against each other.
The sixteen molars used to grind the beaver's woody food seldom show any sign of wear. Small twigs are fed into the mouth with the front feet, nipped into small pieces by the front teeth, chewed by the molars, and swallowed. When eating bark off larger sticks, the beaver picks up a piece about a foot long.
One "hand" closes around it and the other grips it between the little finger and the other four. The stick is turned quickly and evenly by the fingers and moved slowly sideways. The sharp front teeth strip off the bark as you might eat corn off a cob. When its mouth fills with bark, the beaver pauses, chews, swallows, sharpens its teeth, and then continues eating. Upon nearing the end, it holds the stick against the "palm" of its "hand" so the teeth can eat right up to the edge.
The cleaned stick is then tossed aside and another is picked up. The discarded sticks have an almost threaded appearance because of the grooves the teeth cut while removing the bark from the turning stick. Later these cleaned sticks will be used to reinforce the beaver's dam. A beaver dam is a remarkable structure, but the builder's reputation for engineering intelligence may be slightly exaggerated.
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