Past Species of the Week: Critters (mammals, amphibians and reptiles)

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2008

(July 5 - 11, 2008) American beaver Castor canadensis  (Beaver Family Castoridae)

The largest member of the Rodent order in Wisconsin, the American beaver is a mostly aquatic mammal who's distinct features are well-suited to life in the water.  It is 3 to 4 feet in length and weights from 20 to a whopping 60 pounds for the longest-lived specimens.  They have reddish-brown waterproof fur and a large, scaly paddle-shaped tail that helps it propel itself in the water.  It's hind feet are webbed and it's eyelids are like goggles, the clear membranes allowing it to see underwater while still protecting it's eyes.  It also has specialized ears and nostrils, with valves that close while underwater.  It's high-capacity lungs allow it to remain underwater for up to 15 minutes at a time.  Special lips seal the mouth yet allow the front teeth exposed to allow it to carry tree branches in it's mouth while swimming without letting water in. 

 Beaver are monogamous and mate for life, but will take a new mate if it's partner dies.  They have been known to live up to 20 years in captivity, although a more realistic age for them in the wild is 10 to 15 years.  They build a lodge of tree branches in the water for denning, which is hollow inside with holes in the top to allow air in.  The entrances are underwater. The young grow rapidly and remain with the parents the first winter in the den, then help them the next summer maintaining the den and storing the next winter's food while the parents raise the next litter.  They disperse after two years to start their own families. 

Beavers have specialized teeth which allows them to gnaw down the trees that they use to build their lodges and dams.  If you find a felled tree or remnants of one with large amounts of woodchips at the base, most likely it was felled by a beaver.  They usually cut the trees and make repairs to lodges and dams at night.  Beavers are  the only animals other than man to have made such grandiose changes to their environment.  The dams they build create ponds.  These ponds play an important role in moose populations in the north.  Moose feed on aquatic plants and escape biting insects in the beaver ponds during the summer.  Other animals, including frogs, turtles, and many birds rely on beaver ponds for their survival. 

The American beaver was once nearly extinct due to trapping for it's much-sought-after pelt in the 1800's.  They have made a remarkable comeback and are quite common at Crex Meadows and Fish Lake.  In fact, one of the things that make beavers so interesting, their ability and fondness for building dams, is a constant source of consternation for the crew at Crex.  They like to dam up the water structures in some of the flowages and the crew often finds it necessary to remove the dams to keep the flowages "flowing". 

(June 21 - July 4, 2008) White-tailed deer Odocoileus virginianus  (Deer Family Cervidae)

 The white-tailed deer is reddish-brown in the summer and grayish-brown in the winter.  They have large ears that are white inside and have black rims.  They have white on their eye-ring, nose band, chin, throat and belly, and their 6-12 inch tail is bright white on the underside.  The males can weigh up to 300 pounds and the females up to 250 pounds.  They are generally 4 to 7 feet in length and 3 to 4 feet tall at the shoulder.  White-tailed deer generally live 5 to 10 years. 

White-tailed deer are common to abundant in this area.  They live in the forests and in the meadows and prairies.  The do not den or nest, but rather roam wherever food is in good supply.  They do not tend to sleep in the same spot each night, but beds may be concentrated in one area.  They do not need shelter in bad weather, but may move to a semi-sheltered area with good food supply (yards) in the winter months.  They eat grasses, plants, twigs and buds of trees, and acorns. 

White-tailed deer breed in October and November and give birth in May or June.  The mothers generally lay down wherever they happen to be when it is time to fawn, and the newborns, covered in white spots, usually walk within hours after their birth.  Fawns may bleat, and males grunt and snort during the rut.  They are a much-hunted creature, with the bow-hunting season correlating with the breeding season, and the gun season starting just afterwards and continuing into December for some types of guns, such as muzzleloaders.  Their main predator, besides man, is the Gray Wolf, which has made a strong come-back in this area.  Despite heavy predation from hunting and wolf predation, the White-tailed deer population remains strong.

(June 21-27, 2008) Striped Skunk Mephitis mephitis (Skunk Family Mephitidae)

The striped skunk is the largest skunk in Wisconsin, more than twice the size of the only other skunk found here, the Eastern Spotted Skunk (this one is extremely rare in WI).  It is 20 to 24 inches long, with a 7 to 14 inch long tail.  It weighs 6 to 12 pounds.  It's fur is black with two broad white stripes that begin joined at the head and separate down the back and blend into the tail. There is usually a thin white stripe down it's forehead.  The male is larger than the female.  It lives 2 to 5 years, and prefers woodlands, river bottoms, farmland, prairies, fields.  It is found in both suburban and urban settings.

 The striped skunk burrows, often in a tree crevice or hollow log, in wood and rock piles, and under decks and porches.  It is an omnivore, preferring bugs, small mammals and reptiles, spiders, earthworms, as well as seeds and berries.  

Skunks mate in late winter/early spring and has a litter of 4 to 7 young, usually in mid-may.  The young have black and white skin, matching the fur pattern it will develop as it grows into an adult. 

Skunks are mostly nocturnal, and are more active in the summer than in the winter.  If you see a skunk during the day, be wary as it may be rabid.  Skunks are known to be the most susceptible to rabies of all mammals.  Of course, fear of the odor a skunk may emit as it sprays someone coming too close should keep you as far away as possible anyway.

2007

(September 1-7) American Badger Taxedea taxus (Weasel and Skunk Family Mustelidae)

 The American Badger is a one of the larger members of the weasel family, larger than a skunk or woodchuck, but smaller than a wolverine.  It's fur is coarse and grizzled gray on top and yellowish brown underneath.  It has a dark snout and a white stripe along the top of it's head, white cheeks just outside the eyes and white neck and ears.  It's body is wide and flattened, with short powerful legs and long, sharp nails on it's feet.  The male Badger is larger than the female, growing up to 30 inches in length and weighing up to 25 pounds.  It lives up to 10 years and is a native species to Wisconsin. 

The American Badger is common and widespread in Crex Meadows and Fish Lake Wildlife Areas.  It's den is usually built into a hillside with an opening that is wider than it is tall, with a large pile of dirt in front of the enterance.  It sometimes overtakes woodchuck dens and enlarges it for it's own purposes.  The Badger eats small rodents and large insects, small birds, eggs, snakes, frogs and toads.  It is noctournal but occasionally leaves the den during the day.

As you travel through Crex Meadows, look for holes dug along the edges of the gravel roads.  The Badger has dug these in search of the gophers and ground squirrels that burrow along the edges of the roads.  The Crex crew spends time every week filling in these holes, which can become quite large and dangerous for our tires if left to erode! 

(August 28-31) Common Snapping Turtle Chelydra serpentina (Family Chelydridae)

The Common Snapping Turtle is Wisconsin's largest and heaviest turtle species. Its carapace (the dorsal, convex part of the shell structure of a turtle, consisting primarily of the animal's broad ribcage) can vary from light brown to black in color and it has a saw-toothed back edge. The tail supports a row of jagged dorsal scales and is nearly as long as the carapace. The head has large jaws and a pointed snout with a prominent beak. Its long neck, powerful jaws and aggressive behavior have rightly earned the snapping turtle its name.

The often yellowish-colored plastron (the nearly flat part of the shell structure of a turtle or tortoise, what one would call the belly, similar in composition to the carapace) is greatly reduced, leaving the limbs very exposed from the underside.

Snapping turtles live in most aquatic habitats but prefer ponds, lakes and the backwaters of rivers. Both a predator and a scavenger, the snapper feeds on aquatic animals and plants. They consume almost any animal they can catch, although studies show that their reputation as a duckling predator has been greatly exaggerated. They also feed on slow-swimming, small fish, or fresh dead fish. Snapping turtles are important top-line predators in aquatic food chains.

These turtles have been sighted along Phantom Lake Road along the water edges and crossing the road during the past few days.

This information was stolen from the Wisconsin DNR website http://www.dnr.wi.gov/org/land/er/herps/turtles/comsnap.htm with a little help from Wikpedia.

(August 4-17) Red Fox Vulpes vulpes ICanidae family)

At 2 feet long and a foot or so tall, the red fox is the smallest of the Canids found at Crex Meadows.   It usually has rusty red fur with dark highlights but can sometimes be seen with light yellow to black fur.  It's large pointed ears are trimmed with black and are white inside.  It's chest and belly are usually white, and the legs are nearly black.  It's large bushy tail is about a foot long and is normally darker brown than the rest of the body, always with a white tip, which is absent in all other canids.  It's winter coat it much denser than it's summer coat. 

The Red Fox, like other canids, digs a den for it's pups.  It usually enlarges a woodchuck den, uses a hollow log, or digs a den beneath a large log, rock or in a bank of a stream or hillside.  The den differs from the Gray Fox's den in that it often has a small mound of dirt at the entrance of the den.  It has 1-10 pups, usually in late April or May.  These young leave their families at the end of the summer and travel as far as 150 miles to find their own territory. 

The Red Fox feeds on small mammals and eats berries, apples, nuts, fish, insects and road-kill.  They can hear low frequencies which helps it locate digging mice, moles, and other rodents that supply the majority of it's diet.  It hunts even when it is full, and will store it's food underground or buried in the snow. 

Look for the red fox throughout Crex Meadow and Fish Lake.  They have been spotted many times along Abel Road between Phantom Lake Road and Main Dike Road.   

(July 28 - August 3) Northern Green Frog Rana clamitans melanota

Green frogs have a light to dark olive green or brown background color with small, irregular dark brown spots. Spots are often more numerous in juveniles. They have prominent dorsolateral folds that run from behind the eye to about mid-body. Like bullfrogs, adult male green frogs have bright yellow chins.

The Green Frog is divided into two subspecies, the Bronze Frog, clamitans, and the Northern Green Frog, melanota. The Bronze Frog is a medium sized frog attaining lengths around 3 inches; the Northern Green Frog is slightly larger reaching sizes of 3.5 inches. As in some other species of frogs, the gender of the individual frog can be determined by the size of the tympanic membrane relative to the eye. It is considerably larger than the eye in males and about the same size as the eye in females. Also, males are often a bright yellow as shown below right. Northern Green Frogs usually have more green coloring on the back, but are often more brown than green. They also tend to have dark markings on the back.

Their calls are low "gung-gung-gung" - like strumming on a loose banjo string. Eggs are laid in a mass attached to floating vegetation on the water's surface. Because their young often overwinter as tadpoles, green frogs require permanent water, like deep marshes, large ponds and lakes. Recent studies show that heavy shoreline development significantly reduces populations, primarily because of lost natural shoreline vegetation.

Northern Green Frogs can be found in most of the waterways within Crex Meadows and Fish Lake Wildlife Areas.  The one in the photo above was found in the pond behind the visitor center.

(July 21-27) Blanding's Turtle Emydoidea blandingii

The Blanding's Turtle is a medium-sized turtle most readily identified by the yellow underside of it's neck, which brightens at 3-5 years of age.    The underside of it's shell is also yellow, with brown or black splotches and the upper shell is usually black with yellow spotted patterns.  The head, feet, and tail are a blue-black.  Adults are 8 to 10 inches long and weigh up to 3 pounds.  Males are larger than females with longer tails and concave plastrons (belly - the flat part of the underside of the shell) for mating.  The turtle's plastron is hinged, which allows it to close the front part of the shell tightly which protects the head, neck and legs from predators.

Blanding's Turtles are semi-aquatic but highly terrestrial, moving from one wetland area to another quite frequently to breed and lay eggs in the spring, and to feed throughout the summer.  It prefers open, grassy marshes containing shallow water, but it will, on occasion, move to ground adjacent to water to forage or bask in the sun. While in the water, it feeds on crustaceans, snails, insects, frogs, and fishes. Crayfish appear to be a preferred food when available. When on land, however, it consumes earthworms, slugs, grasses, berries, and succulent vegetation. The Blanding's turtle is unique because, unlike most turtles, it can swallow food both in and out of the water. During the winter, it hibernates by burying itself in the silt on the bottom of the pond, bay, or river it inhabits which reduces its chances of freezing.

Blanding's Turtles are a threatened species in Wisconsin, but occur frequently in Crex Meadows and Fish Lake Wildlife Areas.  They are more common in the southern half of the state where they are concentrated near the Wisconsin River in the vast marshes of that area.  They do not occur in the north-central part if the state at all.  Watch for Blanding's Turtles crossing the roads where there is wetlands on both sides, especially along Phantom Lake Road and Main Dike Road in Crex Meadows and Stolte Road in Fish Lake.  Please take care to let them cross over before proceeding past them. 

(Much of this info was taken from the WI DNR Website http://dnr.wi.gov/org/land/er/factsheets/herps/bldtur.htm)

(June 30 - July 6) Northern River Otter Lontra canadensis (Weasel and Skunk Family Mustelidae)

The Northern River Otter is a long, sleek dark-brown mammal that is more at home in the water than on land.  It grows up to 3 1/2 feet in length and stands up to 20 inches high (on all fours).  It has overall dark brown-to-black fur with a lighter brown-to-gray belly and a silver-gray chin and throat.  It's ears and eyes are small and it's snout is short with white whiskers.  It has a long, thick tail, tapered at the end, which aids it in swimming.  The male is larger than the female.  It is a species native to Wisconsin and lives 7 to 20 years. 

The River Otter inhabits lakes, streams, rivers and ponds.  It builds a den in a riverbank or lakeshore, most often with an underwater entrance.  It sometimes uses a abandoned beaver lodge.  River Otters are not very afraid of humans and will sometimes allow us to get a good close-up view of them.  They are playful creatures and enjoy sliding on their bellies in mud and on ice. 

In Crex Meadows and Fish Lake, otters are often seen in the late winter as ice breaks up along the shorelines of the larger flowages.  In summer, they can sometimes be seen near the roadsides playing in the mud when the water levels are low, or swimming in the larger bodies of water.  Look for long uninterrupted tracks where they have moved through the mud along Phantom Lake Road.  The family of otters in the photo above were observed near the #3 Auto Tour sign on June 26th enjoying the mid-day sun.  It was 94 degrees that day, so the heat does not seem to bother them.

See main Species of the Week page for references.

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