An online resource based on the award-winning nature guide

Rodents

Meadow Voles Soon To Begin Breeding

2-23-16  meadow vole 036

Under perfect conditions, with no predators, no deaths and abundant food, a pair of meadow voles (Microtus pennsylvanicus) could produce a million descendants in a single year. Because they are prey for nearly every meat-eating animal that exists, however, their population, while large, is nowhere near this.

Even though the number of meadow voles is relatively high and they are active day and night, year round, it is unusual to actually set eyes on one. What we do find, especially this time of year, are meadow vole signs in the snow: mazes of runways on the surface of the ground that are exposed as snow starts to melt, air-exchange holes originating in their tunnels and extending to the surface of the snow, tracks and entrance/exit holes to their tunnels.

The social behavior of meadow voles is about to undergo a seasonal change. During the winter, when they are not breeding, meadow voles are more social and commonly share their nests, probably to conserve heat. In another month, however, as breeding begins, females become fiercely territorial towards other females, and males are aggressively establishing dominance over each other. The peaceable subnivean meadow vole kingdom is about to come to an end. (Thanks to Susan and Dean Greenberg for photo op.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Porcupine Tracks

2-5-16 w's porcupine IMG_3938Alas, yesterday’s Mystery Photo ‘twas not made by a squirrel loaded down with a bag of nuts, a guess hazarded by one reader, but, as most of you knew, it was created by a Porcupine, or Quill Pig (Erethizon dorsatum). A bit pigeon-toed, Porcupines walk with their feet pointed slightly inward, with their feet flat on the ground. Their pebbly soles rarely leave a distinctive pattern, and their toe pads are not usually evident, but under the right conditions, their nails do make an impression. Usually a Porcupine’s quill-laden tail is raised slightly as it moves, but occasionally it drags along the surface of the snow as the Porcupine walks, producing a broad band composed of very fine lines that weaves between the Porcupine’s tracks, as in yesterday’s photo.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Beavers To The Rescue

12-23-15 beaver dam & pussy willow IMG_5739With peepers peeping and pussy willows starting to poke their heads out of local willows in mid- late December, it is clear that in the coming years humans will need to adapt to the effects of climate change. Help with that mission may come from many sources, including beavers, whose landscape alterations have been shown to mitigate many of the more extreme conditions caused by climate change. Where beaver dams are persistent, they may sequester sediment and create wet meadows that can moderate floods, augment early summer baseflows, sequester carbon in soils and standing biomass, decrease ecological problems posed by earlier spring stream recession, and potentially help cool early summer and post-wildfire stream temperatures. (Jeff Baldwin, California Fish & Game) How fortunate that silk hats became fashionable in the early 1800’s, decreasing the demand for beaver pelts and rescuing beavers from extinction.


Meadow Vole Nests

meadow vole nest  089Meadow voles (Microtus pennsylvanicus), tiny mouse-like rodents, spend a majority of their time on the surface of the ground, particularly in moist fields filled with grasses and sedges. They have elaborate runways through the vegetation – well-worn trails about the width of a garden hose which they keep mowed down with their incisors. Latrines of small brownish-green pellets can be found intermittently along the trails.

Most meadow vole nests are constructed out of dried grasses, also on the surface of the ground, although they are sometimes built at the end of shallow burrows. When above ground, the nests are often located in the center of a grass tussock, where they are less apt to be flooded. When there is snow on the ground they are a bit easier to find, as the heat of the voles inside the nest melts away the snow, forming a chimney that sometimes reveals the nest below.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Rodent Incisors

12-3 woodchuck skull IMG_7187Rodents have two pairs of incisors that oppose each other; two in the front of the upper jaw and two in the front of the lower jaw. These four teeth never stop growing, and thus have to be constantly filed down. (Squirrel incisors grow about one-half inch a month.) While nipping herbaceous plants and cutting into bark help do this, it isn’t enough to significantly wear down the teeth. When mice, beavers, woodchucks and other rodents nip or gnaw food, they move their jaws in such a way that these two pairs of teeth grind against each other. Most rodents have hard orange enamel on the outer side of their incisors (woodchucks are our only rodent with white enamel), and softer dentine in the back. When the incisors grind against each other, the dentine wears away faster than the enamel, creating a sharp, chisel-shaped edge to the incisors. This, more than anything else, keeps the growth of rodent incisors under control, just as a nail file keeps our nails from getting too long.

If a rodent breaks an incisor, there is nothing to wear down the opposing incisor. The tooth opposite the missing incisor will continue to grow unchecked in a circle until it causes the death of the rodent, either by piercing its skull or by preventing the animal from being able to eat. In the pictured woodchuck skull, the lower left incisor has broken off, allowing the upper left incisor to grow through the woodchuck’s palate and into its brain.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Red Squirrels Winter-proofing Nests

11-18-15 red squirrel2  032Red Squirrels are active year round and have nests that they can retreat to at any time of the year. These nests are used for shelter and rest, for over-wintering and as brood chambers. Red Squirrels build them in a variety of spots (tree cavities, old woodpecker holes, middens, rock piles, rotting logs, tree canopies) with a variety of material (twigs, branches, leaves, shredded grape bark, etc.).

Regardless of where they build their nest or what they build it with, Red Squirrels line it with fine, relatively soft material, such as grasses, bark fibers, feathers and fur. If a Red Squirrel happens upon potential nest-lining material, including an old dog towel hung out to dry, it will readily chew it into shreds and carry them back to its nest.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Eastern Chipmunks Soon To Encounter Round the Clock Darkness and Periodic Torpor

11-6-15  eastern chipmunk IMG_0439Although Eastern Chipmunks are much in evidence during our current November heat wave, these lively rodents will soon retreat underground to their maze of interconnecting tunnels for the winter. This burrow system usually has one unobstructed entrance with the opening of other tunnels that lead to the surface plugged with leaves. A chipmunk may dig part of the burrow system using its forefeet and cheek pouches to loosen and transport soil, but the renovation of old root channels and existing burrows of other mammals is the primary method of burrow construction. The two-inch diameter tunnels are roughly 12 to 30 feet long and typically 18 to 36 inches deep. Off of these tunnels are several food galleries as well as a chamber six to ten inches in diameter which contains a nest of leaves.

Chipmunks reside in their subterranean environs from mid-November until early March – late April, with local snow depth and temperatures influencing the duration. They are not true hibernators and accumulate little body fat prior to winter. Throughout the winter chipmunks are aroused from their state of torpor every week or two and snack on their underground caches of food (up to 5,000 – 6,000 nuts per chipmunk, according to one source). During mid-winter thaws, some chipmunks may leave their burrows, even digging through several feet of snow to forage for seeds in nearby areas where the snow has melted and the forest floor is exposed.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Follow

Get every new post delivered to your Inbox.

Join 4,242 other followers