Muskrats, beavers similar but not related

Muskrats and beavers are similar in many ways which is surprising since they aren’t even close relatives. Muskrats are more closely related to voles and lemmings than to beavers. 

Both are semiaquatic rodents that slap their tails when alarmed. However, a beaver’s tail is flat like a paddle and a muskrat’s tail is like a rat tail--scaly and nearly hairless. 

Muskrats are more buoyant than beavers, so more of their body is visible when swimming

Both are able to swim underwater for over 15 minutes and also feed underwater. Muskrats and beavers can both close their lips behind their incisor teeth to harvest food underwater but they feed on different food. Muskrats eat aquatic plants such as cattails and bulrush, including the shoots, bulbs, roots, tubers and leaves. They will also eat the occasional small fish, snail or turtle. Beavers eat bark, twigs, leaves, roots and green vegetation, which can include sedges, grasses and pond lilies. 

Like beavers, muskrats build lodges except that their lodges are made of cattails and sedges, not sticks. Muskrats build in shallow water and access the nest chambers via underwater tunnels like beavers. A muskrat lodge is smaller than a beaver lodge with a diameter of six to eight feet at the base. 

Muskrats also excavate burrows in shoreline banks like beavers that live in rivers. Muskrats prefer denning in banks than living in lodges if conditions allow possibly because less maintenance is needed and they are cooler in the summer. Unlike beavers whose den entrances are underwater, a muskrat’s den entrance can be above or below water. 

Muskrat lodges can often be found in beaver ponds because beaver dams increase habitat for muskrats by flooding new areas. They are able to occupy the same habitat because there is no apparent competition for food. Muskrats are more commonly found in shallow marshes with abundant cattails verses wooded areas that beavers prefer. 

A muskrat has a small home range compared to a beaver, often less than 200 feet in diameter, which is roughly half a football field. Depending on the location a beaver can have a home range of half a mile. 

Within that home range, muskrats build a lodge and feeding shelters (sometimes referred to as “push-ups”). During the winter, muskrats build feeding shelters on the ice as a place to feed, rest and warm up. The shelters are constructed by the muskrat pushing various types of debris up through a hole in the ice until it forms a heap that is large enough to include a cavity for the muskrat to sit. When the shelter becomes covered with snow, there is enough insulation to keep the hole in the ice open. 

The feeding shelters are built within the dive limits of the muskrat, which is longer in the winter because their oxygen-storing capacity increases by 42 percent. This allows the muskrat more access to submerged vegetation in the winter. Beavers, on the other hand, build a raft of wood near their lodge to feed on during the winter so they don’t have to actively forage. 

In the warmer months when both are foraging, it may be hard to see them since they are both nocturnal. Both can be active during the day, especially muskrats on rainy, overcast days, but they prefer to be nocturnal to stay hidden from predators. 

When beavers swim, sometimes only their head is visible

Once spotted, there are two major differences that distinguish the two. When swimming a beaver has one hump consisting of its head, neck and upper back or just its head. Whereas a muskrat while swimming has two or three separate humps--its head, its upper back and sometimes its tail. 

The other difference is size. A muskrat weighs roughly two-and-a-half pounds, while a beaver weighs between 35 to 70 pounds. 

Note: Published in the Bonners Ferry Herald on Nov. 29, 2012. 

Feast or famine for animals in the winter

Last weekend, the chickadees and nuthatches finally found the two bird feeders I filled several weeks ago. For birds, finding a full feeder is like finding a Thanksgiving feast. 

Surviving winter is feast or famine for animals that don’t migrate or hibernate. Plentiful insects, fruits and green vegetation are gone or hard to find. Once an animal finds a feast, it will frequently come back, eat it all at once or cache it away for times of famine. 

The chickadees and nuthatches don’t stay at my feeder all day, but come in waves. They make their rounds between known food sources--maybe even the neighbor’s bird feeders. Before they found my feeders, they fed on the cones in the Douglas-fir trees in the yard every morning. 

Some flocks of birds feed almost exclusively on seed crops in the winter which makes their movements highly irregular. Redpolls and goldfinches fly between birch stands to feed on small birch seeds. Flocks of crossbills seek out spruce and pine trees to feast on the seeds that their bills are specifically adapted to pry out of the cones.

Flock of pine grosbeaks on cone-laden tree

Hemlocks are the tree of choice for pine siskins whose long, thin bills reach under the bracts of hemlock cones. Waxwings travel in flocks and descend upon berry-laden trees or shrubs and feast until every last berry is gone. 

Birds such as waxwings, redpolls and grosbeaks will fly out of their typical range in search of seeds or berries if there is a crop failure in their regular range--which is one way to avoid famine in the winter. 

Gray Jay

Another way animals avoid famine is to cache food when it is abundant. Only a small percentage of species worldwide cache food for winter. Gray jays cache food all year long by wadding food into a ball, coating it with saliva and wedging it under tree bark. As long as they cache enough food, their excellent memory prevents them from famine in the winter. 

Living in mountain talus slopes, the resourceful pika makes hay in the summer by drying grasses and stockpiling it deep within the rocks where snow can’t reach it during the winter. 

Pika collecting vegetation to dry

Red squirrels are notorious for their caches of cones, called middens, scattered throughout the forest. Unlike the mushrooms that squirrels harvest and dry in the crotch of tree branches, they prefer to keep the cones moist. Dry cones are less palatable, so the cool, damp depths of middens are perfect for storing cones.

Squirrel midden

A few other rodents that stockpile seeds for winter are deer mice, pocket mice and chipmunks. A larger rodent, the beaver, stockpiles trees underwater to feast on all winter. 

Fewer animals stockpile meat for winter. Saw-whet and great horned owls create their own frozen dinners by killing and stockpiling mice. Then to eat a mouse, the owl sits on it like it is incubating an egg until the mouse is thawed enough to tear apart and eat. 

Then there are those animals that take advantage of other species caches to survive. Elk and deer feast on hay bales in fields and barns, turkeys feed on grain spilled next to grain bins, and birds feast on the cache of sunflower seeds hanging outside my window.

Note: Published in the Bonners Ferry Herald on Nov. 21, 2012. 

Leonid meteor shower peaks this weekend

Shooting stars are always exciting to see. Sometimes I only see them out of the corner of my eye, other times I’m lucky enough to be looking at the right part of the sky at the right time. 

Star trails with satellite crossing sky

Despite resemblance in brightness and size, shooting stars are not stars streaking through the sky but instead are meteors. Meteors have nothing to do with stars. Meteors are bits of interplanetary rock or debris that have fallen or broken off comets or asteroids and enter Earth’s atmosphere. Outside of Earth’s atmosphere, these rocks are called meteoroids.

Most meteors are smaller than a garden pea. Larger meteors do exist but they are less common. Meteors that are barely visible to the naked eye are usually only 0.55 millimeters in diameter--that’s smaller than a grain of rice!

When a meteor streaks across the sky, we aren’t seeing the meteor itself. We see the light emitted from reactions between the friction of the rapidly moving meteor with the gases in the atmosphere.   

Big Dipper

Meteoroids enter the atmosphere at tremendous speeds--between 25,000 to 160,000 miles per hour. They quickly ignite from searing friction with the atmosphere. The outer layer of the meteor is vaporized and stripped away due to high speed collisions with air molecules. 

The composition of a meteor and the colliding air molecules are responsible for a meteor’s color. Since the source of meteors varies, the elements within the rock or debris varies. When vaporized, each element emits a signature color. Meteors containing sodium will be orange-yellow, iron will be yellow, magnesium will be blue-green, nickel will be green, and ionized calcium will be violet. When a meteor appears red, the reactions of the atmospheric nitrogen and oxygen atoms are overpowering the reactions of the elements in the meteor. 

A meteor’s velocity can also impact its color and brightness. Slow meteors tend to be red or orange while fast meteors are frequently blue. Faster meteors are also brighter. 

Watching for meteors provides a chance to look at the stars

Most meteors only streak across the sky for a short time before they burn up in the atmosphere, typically between 60 to 80 miles above the Earth’s surface. If a meteor does make it to the Earth’s surface, it is called a meteorite. 

Interestingly, most meteorites tend to be from slow meteors. Nearly all meteorites originate from astroids but astroid-originated meteors only comprise five percent of the meteor population. The other 95 percent of meteors originate from comets and they rarely make it to the Earth’s surface. 

Meteoroids originating from astroids are created when something collides with the astroid and a piece is chipped off. These meteoroids typically create the sporadic meteors not associated with meteor showers. 

Comet-originated meteors are the ones seen during meteor showers. As a comet orbits around the sun, the heat from the sun causes the comet’s outer layer to vaporize and particles to “fall off” in the form of comet dust. 

Always a chance of seeing the unexpected

If the comet’s path crosses Earth’s orbit, then a meteor shower will occur when Earth passes through the comet dust every year. Since Earth encounters the comet dust at the same time every year, meteors seem to radiate from a specific constellation in the sky every time. Meteor showers receive their name by the constellation they radiate from. For example, the Leonid meteor shower radiates from the constellation Leo. 

November is when Earth passes through the comet dust that creates the Leonid meteor shower. The Leonid shower begins on Nov. 13 and ends on Nov. 21, with the peak around Nov. 17 or 18. At the peak, up to 10 meteors per hour will be visible. However, the Leonid meteor shower is cyclic like sunspots and has a cyclic peak every 33 years that is associated with the return of its parent comet into the inner solar system. During this cyclic peak, hundreds to thousands of meteors can be visible every hour--but that peak won’t be until around 2028. 

Note: Published in the Bonners Ferry Herald on Nov. 15, 2012. 

Sign Posts of the Forest

Wandering through the woods, I found a tree with claw marks scratched in the bark at eye-level and black hair stuck to once oozing sap. The culprit--most likely a black bear sometime this summer. 

Black bear claw marks and sapsucker holes

After I found the claw marks, I started to look for more animal sign on trees. On the same tree right next to the claw marks, were lines of square holes drilled into the bark--a sapsucker. True to their name, sapsuckers drill the holes to allow sap to ooze out so they can lap it up. 

Sapsuckers drill holes for sap

Sap is also the motive for black bears to peel the bark off the lower portion of trees, sometimes even girdling the tree. On the same wander in the woods, almost every larch tree for a few hundred yards had a section of bark removed from the base. Black bears go after the sweet tasting sap in spring and early summer and signs of their destruction last for the life of the tree. 

A black bear girdled this larch tree by peeling off the bark for the sap

Likewise, one single climb up an aspen tree by a black bear may be seen for the entire life of the tree since the claw marks scratched into the soft, smooth bark can become scabbed over. 

Aspen trees may also have rough, blackened trucks to the height an elk can reach. Elk like to gnaw on the aspen trees in winter, which causes the tree to scab over. 

Gnawing on trees, especially during the winter, is a habit on many animals and key to their survival. Porcupines gnaw large patches of bark off tree trunks and eat the bark off twigs. Their gnawed areas have neat edges, irregular outlines and numerous small toothmarks, which help distinguish them from elk or moose sign. 

Closer to the ground, snowshoe hares will feed on the bark of trees. However, when they feed on the cambium, they gnaw far beyond the bark into the woody center unlike other animals. 

Then there is the gnawing champion--the beaver--who gnaws through an entire tree trunk to fell a tree. In addition to eating the bark and wood, beavers need to constantly gnaw on trees to wear down their continuously growing teeth. 

Beaver sign

Instead of gnawing, woodpeckers drill into trees to find insects to eat or to excavate a nest cavity. Some of these sought after insects leave their own sign. Ever notice the insect trails on the inside of bark or the outer edge of wood when peeling the bark off for firewood? Birds will debark a section of tree to access these insects, such as bark beetles, and will expose the insect’s trails.

Woodpeckers hammered this tree for insects

Insect trails in wood

Some tree signs aren’t related to food. A medium-sized sapling with its bark shredded and small limbs broken reveals the presence of an elk or deer rubbing or thrashing its antlers on the tree during the rut. 

A deer rubbed the branches off this sapling

While not as obvious as elk or deer, bears will rub against a tree to remove their winter coat or unwanted parasites, often leaving behind hairs in sap or on bark. They need a back scratch too!

More animals than mentioned here let their presence be known, whether purposely or not, on sign posts in the forest. We even leave our sign on trees, in the form of trail blazes, so that we can find our way through the forest.  

Note: Published in the Bonners Ferry Herald on Nov. 8, 2012. 

Autumn reveals hidden hornet nests

As the yellow leaves of autumn drop from trees, they often reveal hidden treasures such as bird nests and less desirable wasp nests. The gray, papery football- to basketball-sized nests normally hidden by leaves are home to bald-faced hornets during the warmer months. Other paper wasps such as yellowjackets also create paper nests in varying shapes and sizes. Despite their name, bald-faced hornets are members of the yellowjacket family.

A bald-faced hornet nest that once was hidden by leaves

These visible nests in late fall and winter are the result of a summer’s worth of work by many hornets. The entire nest is built from wood fibers that each hornet has gathered, chewed and mixed with salvia in their mouth to form a soft wood pulp. The varying colors on the outside of the nest (called the envelope) result from different sources of wood fibers, which can include weathered and rotting wood, fence posts, dead plants, cardboard or newspaper. 

Varying colors a result of different sources of wood fibers

The queen bee initiates nest building by adhering wood pulp to a structure, such as a tree branch, that will hold the nest, typically at least three feet off the ground. Then the queen starts building the nest with a horizontal layer of hexagonal cells on the inside and a papery, protective envelope on the outside to the size of a golf ball. 

In those first cells, the queen will lay eggs that will become adult workers. Upon hatching and pupating into adults, the workers will take over the nest building and feeding the larvae while the queen solely lays more eggs in the cells they create. During the height of production a nest may hold up to 700 hornets. 

Inside of a hornet's nest

The workers keep building the nest one mouthful at a time until it is roughly football or basketball size. They will create several horizontal layers of cells on the inside and a one-to-two inch multi-layered envelope on the outside while leaving a small, round hole near the bottom for an entrance. 

Workers leave a small hole at the bottom for an entrance

Two sizes of hexagonal cells are created: small and large. The majority of the cells will be small and will be utilized up to three times during the summer to raise worker hornets. Starting in the fall, single-use larger cells will be constructed to raise the future queen hornets and the males (drones) that will mate with the newly hatched queens. 

Mated queen hornets are the only ones to overwinter--the remainder die off when the temperature drops below freezing, including the reigning queen. Despite the thick outer envelope on the nest that keeps the hornets warm in the spring and fall and cool in the summer, it isn’t enough protection for a new queen in the winter. Instead, she will spend the winter in a crevice under tree bark, in a tree stump, behind house siding or in the eaves of a house. Come spring, the new queen will begin her own nest since bald-faced hornets do not reuse nests. 

Bald-faced hornets still occupying a deteriorating nest in late autumn

The abandoned nests don’t go unused--spiders and other insects will seek shelter in the nests during winter. However, insect-seeking birds easily hone in on the exposed hornet nests dangling in bare trees and will readily shred the nests looking for slumbering insects, which truly makes the nests hidden treasures. 

Note: Published in the Bonners Ferry Herald on November 1, 2012.