What to notice outside around Sudbury in December
49 things from the field guide you can notice around Sudbury in December.
Sky
- Why you can see the moon in the daytime skyThe moon spends almost as much time up in daylight as at night, and on the right days it sits plainly in the blue sky.
- Sundogs and sun halos: how ice crystals bend sunlightIce crystals high in the atmosphere can bend sunlight into a pale ring around the sun or bright patches on either side of it.
- Crepuscular rays: sunbeams fanning out near sunrise and sunsetWhen broken clouds and haze meet a low sun, bright and dark bands can fan across the sky near sunrise or sunset.
- Geminid meteor shower: the one you can watch before bedtimeThe Geminids peak on December 13-14 and are already going in the early evening, unlike other major showers that ask you to stay up past midnight.
- How the sunset point moves along the horizon through the yearWhere the sun sets on your skyline slides north through spring and south through autumn, fastest near the equinoxes and nearly still at each solstice.
- The Pleiades, Taurus and Orion return to the early evening skyThrough late autumn and early winter the Pleiades, Taurus and Orion climb into the eastern sky earlier each night, changing the bedtime sky month by month.
- Why your noon shadow more than doubles from September to DecemberFrom the September equinox to the December solstice the midday sun drops from about 47 to about 24 degrees here, and your noon shadow more than doubles.
- The Big Dipper never sets from eastern MassachusettsFrom eastern Massachusetts the Big Dipper is circumpolar, circling Polaris once a day, though the tip of its handle skims the horizon at its lowest.
Weather
- Hoarfrost: ice crystals growing on twigs, wires and weed stemsOn the right cold morning, water vapor turns straight into ice and builds crystals on thin things like fence wire while the ground stays bare.
- Why fresh snow makes everything so quietThe hush after a snowfall is real. Fresh snow is mostly air, and that trapped space swallows sound instead of bouncing it back like pavement does.
- Why sound carries so far on cold, clear, calm nightsOn a clear calm night the air at your feet ends up colder than the air above, and that flipped layer bends sound back down so it carries much further.
- Why there is frost when the air never dropped below freezingOn a clear, still night a surface facing the sky loses heat faster than the air, dropping below freezing while the air a few feet up does not.
Birds
- Why robins travel in fruit-eating flocks in fall and winterThrough fall and winter, robins stop patrolling lawns alone and roam in nomadic flocks that live on fruit, which can be over 90 percent of the diet.
- Wild turkey flocks in fall: hens and broods joining forcesIn fall, hens and their grown broods join forces, and New England turkey flocks commonly hold several families, 40 or more birds, sweeping across fields.
- Starling flocks twisting in unison: why they fly as one shapeAutumn starling flocks in Massachusetts fly as one shape-shifting cloud, turning in unison because no falcon can pick one bird out of a swirl of thousands.
- Ducks arriving at Great Meadows in Concord through late autumnDucks keep arriving on eastern Massachusetts marshes after the songbirds leave, and at Great Meadows in Concord, pools reflooded through fall feed them.
- Crows flying to a shared winter roost before sunsetAfter nesting, American crows pile into one enormous shared night roost, and for about an hour before sunset long loose strings of them pass overhead.
- Dark-eyed juncos: the gray winter bird under the feederThe dark-eyed junco, a slate-grey sparrow with a white belly, is in eastern Massachusetts yards from October to April, feeding on the ground under feeders.
- Crow or raven: how to tell them apart by the tailCrows and common ravens are both big black birds, and the tail settles it at a glance: a crow's opens like a fan, a raven's like a wedge.
- Golden-crowned kinglets in the pines from fall into winterGolden-crowned kinglets, among North America's tiniest songbirds, pass through Massachusetts conifers from mid-September through November.
Insects
- Goldenrod ball galls in winter, and the fly larva living insideThe round swellings on dry goldenrod stems, marble to golf ball size, are each a fly larva's winter room, built by the plant on the larva's instructions.
- Mantis egg cases on winter twigsA mantis lays one hard foam case in autumn and dies. The case sits out all winter on a twig or fence post, with dozens to hundreds of eggs inside.
- Small tan moths at outdoor lights on mild November to January nightsOn mild nights from mid-November into January, small tan moths gather at outdoor lights while their nearly wingless mates crawl up tree trunks.
- How honey bees survive winter by huddling and shiveringA honey bee colony stays awake all winter, packed into a ball in the hive and vibrating flight muscles for heat, burning stored honey until spring.
- Bark beetle galleries: the patterns carved under loose barkUnder loose bark on a dead log, a branching pattern in the wood marks a female beetle's egg gallery, with each side tunnel cut by one feeding larva.
Plants
- Next spring's tree buds, already formed at the twig tips by fallTrees in eastern Massachusetts build next spring's buds near the end of the growing season, so by fall every twig tip already carries next year.
- Witch hazel: the shrub that blooms from October into DecemberSpidery yellow flowers with four crinkled ribbon petals open on bare witch hazel branches from October into December, beside last year's fruit.
- Winterberry holly: red berries on bare branches in wet groundWinterberry is a holly that drops its leaves, so by late autumn its fruit stands bare on grey twigs in swampy places and holds there into winter.
- Identifying trees by their bark in winterWith the leaves down, bark tells trees apart: shagbark hickory peels in long strips, black cherry breaks into dark curling plates, red oak runs in ridges.
- Why some beech and oak trees keep their dead leaves all winterAmerican beech and several oaks carry some dead leaves into winter, a habit called marcescence, mostly on young trees and the low branches of tall ones.
- Hemlock groves in winter: less snow, less light, and deer shelterAn eastern hemlock grove is so dense that far less snow reaches the ground and the light dims as you step in, which is why deer gather there in winter.
- Clubmoss: tiny evergreen forests on the winter woodland floorAfter leaf fall, patches of evergreen clubmoss stand out on brown leaf litter in eastern Massachusetts woods, spore-bearing plants related to ferns.
- Oriental bittersweet: the invasive vine with orange and red berriesOriental bittersweet is an invasive Asian vine whose yellow-orange capsules split in fall to show red berries, and birds carry its seeds to new ground.
Mammals
- Beaver signs: chewed stumps and pale wood chips along pond edgesBeavers work mostly at night, so pointed stumps, pale wood chips and paired tooth grooves along a pond edge are often easier to find than the animal.
- Reading animal tracks in snow by the pattern of the whole trailSnow blurs a footprint and widens it as it melts, so print detail misleads. The shape the whole trail makes does not, and you can learn three in a morning.
- Squirrel dreys: the leaf nests that show up in bare treesA drey is a gray squirrel's nest of leaves and twigs, a foot or two wide and usually twenty feet up or more, hidden all summer until the leaves come down.
- Meadow vole runways hidden under matted grassMeadow voles clip networks of inch-wide trails through grass and use the same paths over and over. Part the matted dead grass at a field edge to find them.
Fungi
- Why lichen turns bright green after rainRain turns a lichen's gray outer layer see-through so the green algal partner shows, while lichens with cyanobacteria go dark green, brown or black.
- How fallen leaves turn back into soil over the winterUnder damp leaf piles in eastern Massachusetts yards and woodlots, microbes, millipedes and earthworms turn dead leaves back into soil nutrients.
- Turkey tail fungus on fallen logs through the winterOverlapping fans banded brown, buff and cinnamon cover dead hardwood logs all winter, the visible end of the work that turns a fallen tree back into soil.
- Jelly fungi like witch's butter that swell with rain and shrivel dryWitch's butter and other jelly fungi are rubbery blobs on dead branches that swell after rain, shrivel to a crust in dry spells, then swell back again.
- Black knot on cherry trees: the black lumps are a fungusHard black swellings on a roadside cherry's twigs are black knot, a native fungus, not fire damage or an insect gall, and it can keep growing for decades.
- Artist's conk: the shelf fungus you can draw onArtist's conk is a thick, woody bracket fungus on hardwood trunks and stumps that lasts for years, and its white underside bruises brown when scratched.
Amphibians
- How wood frogs freeze solid in winter and come back in springWood frogs do not dig deep or find shelter. They settle into the leaf litter and freeze, heart and all, and stay that way until the ground warms.
- Bullfrog tadpoles that spend the winter under the iceA bullfrog tadpole usually takes two years to turn into a frog, so a November pond holds last year's tadpoles, still tadpoles when the ice goes out.
Landscape
- Stone walls in the Sudbury woods and the farms they once edgedAlmost every stone wall in a Sudbury woodlot was a field or pasture edge, built of glacial stones farmers cleared between the Revolution and the Civil War.
- Kettle holes: ponds and hollows left by melting glacial iceSome round ponds and deep hollows in eastern Massachusetts mark where a block of ice, stranded and buried as the last glacier retreated, slowly melted.
- Ice needles: frost columns that grow up out of bare wet groundOn a cold morning after wet ground, bare soil can sprout clusters of ice needles that lifted themselves out overnight, each with a little cap of dirt.
- Groundwater seeps: the patches of woods that never freezeGroundwater at a seep arrives near the ground's average annual temperature, so it keeps trickling and stays soft while ponds and brook edges ice over.