Winter Phenology Notes

Phenology is the study of the times when natural phenomena occur and observation of seasonal changes. Phenology is nature's calendar: when flowers bloom, leaves break bud, when birds begin migrating, when leaves change color and begin to fall. We study phenology to better understand the abundance and distribution of different species, food web interactions, global water cycles, and more. Farmers and gardeners use phenology to develop a planting schedule and decide when to apply fertilizers and pesticides. Researchers are using changes in phenology as an indicator of the vulnerability of species and communities to changes in climate.

We invite you to use this collection of notes to deepen your connection to the woods and wildlife around you. These notes can help you pay attention to the natural cycles and processes that happen throughout the year. Make your own notes and compare them from year-to-year. This winter edition of phenology notes is the last of four quarterly articles that have been released with each changing season.

January Phenology Notes

Birds

Barred Owls have been vocalizing their "who cooks for you all" and more excited monkey-ish sounding calls for several weeks. Their breeding will begin around mid-January.

Mammals

A new-fallen snow provides a great opportunity to see animal tracks. Foxes and raccoons are beginning to breed, and skunks venture out during relatively mild weather. Skunks spend the winter in dens in a state of deep sleep called torpor, waking from time to time when the temperature and food availability make movement more desirable. Bear cubs are born to their still-hibernating mothers, who wake just enough to ensure the cubs are warm and nursing.

Plants

On warm days, conifers can carry on some photosynthesis through their needle-like leaves. Deciduous trees remain dormant. Black birch seeds matured in late September through November, but many remain on the tree for dispersal by wind. Look for these three-sided seeds speckling the snow.

Insects

Winter stoneflies may be seen walking along the surface of ice and snow near woodland streams. In mid-winter, the adult winter stoneflies emerge from unfrozen spots in the creeks where they have spent the last year as nymphs (larvae). The adults mate during the winter months, able to survive the sub-freezing temperatures with a type of anti-freeze in their circulatory system.

Fungi

One of the most common of the winter-fruiting fungi brightens up the woods with its colors. The turkey tail, or Polyporus versicolor, has stripes of brown, tan, dark red, green, and grey on the upper side of the mushroom, and the underside is a pale color with many pores. Look for turkey tails on the ends of downed logs and on stumps.

Reptiles and Amphibians

Spring peepers, chorus frogs, and wood frogs are hibernating beneath several inches of soil in the forest. These species endure freezing without damage to their organs and will thaw again when the soil thaws. Eastern American toads are burrowed deeper in the soil, hibernating below the frostline.

General

Days are beginning to get noticeably longer again by late-January. The sunrises are later, but the daylight lasts longer. The day length is around 10 hours by late-January.

February Phenology Notes

Birds

Bald eagles, great horned owls, and barred owls are now sitting on nests, warming their eggs. Turkeys may wander out of the forest and into yards, looking for birdseed now that much of the food on the forest floor has been eaten. A few American woodcocks ("timberdoodles") return in late February.

Mammals

By late February some male woodchucks emerge from their burrows, where they’ve hibernated since late October or early November. Also known as groundhogs or whistle pigs, woodchucks are one of the only mammals who enter into true hibernation. Chipmunks are out and about, beginning to court. Eastern coyotes, foxes, and skunks begin breeding.

Plants

As the days become warmer and the night temperatures are still below freezing, maple sap will begin to flow. Sap is water drawn from the roots of the trees that has mixed with the tree's sugars.

Insects

Snow fleas, one of many species of springtails, can be seen on warm winter days hopping about the snow along a woodland creek. They feed on decaying leaves, fungi, and even soil microbes which have become exposed.

Fungi

Look on the branches of dead elms for the pure white dainty saucer-like fungus Polyporous conchifer. Although seen on many elms that have been infected with Dutch Elm disease, these fungi are also found on the branches and trunks of maples, birches, and black cherry trees. Winter fungi provide an important source of food for deer during this period when other resources are harder to find or unavailable.

Reptiles and Amphibians

Snakes are in a state of greatly reduced metabolism called brumation, This slowed state is comparable to hibernation in mammals, though brumating reptiles are not in a deep physiological sleep and will sometimes emerge to eat or drink on unseasonably warm days.

General

The depth and characteristics of snow may provide different degrees of help or hindrance to various animals. Deeper snows can benefit cottontail rabbits by helping them get closer to the buds of low-hanging tree branches and shrubs that they eat. For foxes, deeper and fluffier snow may mean they expend more energy than usual in chasing and pouncing on prey.

March Phenology Notes

Birds

Flocks of red-winged blackbirds arrive, joining the chorus of American robins at dusk and dawn. Pine warblers and palm warblers are returning. Ruffed grouse begin to mate. Males are busy drumming—flapping their wings to create a drum-like sound that begins slowly then to a speed so fast the individual beats aren't heard. Listen for ruffed grouse in young forests and forest openings. Near a meadow or woodland edge at dusk in late March, you may catch the male American woodcocks perform a dramatic mating flight.

Mammals

Bear cubs just born in January are now able to walk and will soon leave the den, spending about 1½ years alongside their mother. The fisher, a woodland carnivore, gives birth to 3 or 4 kits. Red fox and opossum young are also born now. Chipmunk mating is in full swing. The males announce their territories through repeated chirping. Woodchucks breed now through April.

Plants

The "flower" or spathe of the skunk cabbage, sometimes found just poking out of the ground during the winter months, is now growing. The leaves will develop within 2-3 weeks, providing an easy meal for bears when they leave their dens. Aspen flowers expand and are obvious in mid-March.

Insects

The cocoons of pupating luna moths may be seen—and if disturbed, heard—among the leaf litter, especially near hickory, walnut, birch, persimmon, and sweetgum trees. The pupae overwintered here, following their autumn life cycle phase in which the caterpillars drop from the trees and form cocoons in fallen leaves. As temperatures warm and days lengthen, growth begins again.

Fungi

Scarlet cups, Sarcoscypha coccinea, are growing on hardwood logs and on hardwood sticks nestled below the leaf litter. The inside of the "cup" is bright red, while the outside is muted white with fine hairs.

Reptiles and Amphibians

Spring peepers begin mating. On warm evenings in wetland areas, the peeps can be almost deafening. Wood frogs also call now, sounding almost like a raspy-voiced duck's quack. The northern leopard frog and American toad join the spring chorus and begin to mate. Spotted salamanders move about the forest on nights with temperatures above 40 degrees in search of vernal pools for breeding and egg-laying.

Woodland Nature Journal

If you are interested in keeping your own set of phenology notes, these are adapted from A Woodland Nature Journal: Tracking Changes Through the Seasons, which can be purchased for just $10 to cover shipping and handling.

Each Journal features:

• A water-resistant full-color cover featuring renowned photographer Bill Coleman's four-print collection entitled Seasons
• 218 pages printed on thick cream-colored paper with sturdy wire binding
• Dozens of sketches by artist and forester John Sidelinger throughout
• Plenty of space for you to write, sketch, and collect--to record experiences, observations, and inspirations season after season
• Observation tips provide plenty of resources to help identify plants and animals
• Activities outline ways for you to participate as a "citizen scientist," such as counting and tracking birds, recording plant activity, and monitoring monarchs, to name a few

To order your Journal, call 814-863-0401 or toll-free 800-235-9473, or send a check made out to Penn State University to: Center for Private Forests, 416 Forest Resources Building, University Park, PA 16802. Be sure to include your name, mailing address, phone number, and email address (please print clearly). Cost is $10 each.