Spring 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 spring edition of phenology notes is the first of four quarterly articles that will be released with each changing season.

April Phenology Notes

Birds

Black and white and black-throated green warblers are abundant now and already breeding. Other birds like ruby-crowned kinglets, blue-gray gnatcatchers, and hermit thrushes return to woodland edges and interiors. Wood thrushes and blue-headed vireos have returned to mixed, open forests. Rather than repeating a rival male's song, wood thrushes try to outdo each other by singing a new song.

Mammals

White-tailed deer shed their winter fur. Bucks develop antlers as the daylight lengthens. Bats wake from hibernation and are busy feeding to replenish and prepare for the upcoming mating season. The first litters of chipmunks are born. Raccoon young are born, nestled in hollowed trees. Gray foxes are born now, in litters of 1-7 kits. They are sometimes called “tree foxes" as their dens may be either underground or in a tree cavity as high as 30 feet.

Plants

The forest floor grows colorful again with early woodland wildflowers. Among the first is trailing arbutus, a low-growing evergreen member of the heath family. Smooth-leaved and sharp-leaved hepaticas, wild ginger, twin leaf, and violets also bloom now. Spicebush shrubs show their yellow-green flowers. Red maples are among the first trees to flower, giving a reddish hue to the landscape. Soon to follow are the blooms of aspen, birch, and tulip poplars.

Insects

Mourning cloak butterflies emerge, having spent the winter sheltered as adults. Along woodland streams, little blue wing olive mayflies appear. Adults emerge during late morning within the first week of the month. In mid-April, the little olive caddisfly and little black caddisfly emerge. Caddisflies go through complete metamorphosis, pupating in underwater cocoons. Mayflies skip the pupal stage, emerging as adults directly from exoskeletons developed in their aquatic larval stage.

Fungi

Morels emerge amid the leaf litter when day temperatures are about 60 degrees and nights are above 40 degrees. Look for these tasty fungi in and along the edges of the forests, under elm, ash, aspen, and oaks.

Reptiles and Amphibians

Listen for mountain chorus frogs, pickerel frogs, and green frogs calling. Black rat snakes begin their 2-3 month breeding season late-April. Box turtles emerge from their woodland soil burrows after hibernation. Eastern garter snakes gather to form mating knots, with up to 20 males encircling one female.

May Phenology Notes

Birds

It's a busy and colorful time in the world of birds—scarlet tanagers, rose-breasted grosbeaks, Baltimore orioles, and indigo buntings appear at woodland edges and in treetops with their bright mating plumage. Summer tanagers, blackpoll warblers, and gray-cheeked thrushes also appear again throughout the month.

Mammals

Porcupine pups are born in their rock or tree dens, after a gestation period of 205-217 days. When born, porcupines already are able to open their eyes and have fur and soft quills. They climb trees within a matter of days. White-tailed does give birth late May and into early June, most within a single week.

Plants

Black cherry trees, sassafras, red oaks, and blackhaw viburnum are flowering. Trees leaf out during the first half of May in most of Pennsylvania, often prompted by a good rain that follows warm days. Wind pollinated tree species produce pollen either just before or during leaf-out, so that the pollen is blown to the flowers without interference from the leaves. As the trees leaf-out, the ephemeral woodland wildflowers begin to wane. Late-spring woodland wildflowers blooming now include mayapples, trillium, and yellow and pink Lady's slippers.

Insects

More butterflies are becoming active, laying eggs on the leaves of trees and herbaceous plants. The spring azure often lays its eggs on the flower buds of dogwoods, blueberry bushes, and viburnums. The Eastern tiger swallowtail is spotted frequently feeding on the nectar of black cherry blooms.

Fungi

Overlapping with morel mushrooms in timing, dryad's saddle (Polyporus squamosus) mushrooms are also found often in the same areas. Look for them at the base of dead or dying elm trees. Also called the pheasant back mushroom, this shelf mushroom has a light brown color with darker feather-like markings on the top side. The underside is white and has many pores rather than gills (making it a polypore mushroom). It has a characteristic scent when cut, similar to a watermelon rind.

Reptiles and Amphibians

Fowler's toads are beginning to mate. Their call is a nasal "wraaah," relatively high-pitched in tone. Toads lay their eggs in long strands, whereas frog and salamander eggs are laid in globular clusters. Frog and salamander larvae hatched from eggs laid in early spring are close to metamorphosis.

June Phenology Notes

Birds

Mating and territorial calls continue among birds that rear multiple broods, while the songs of species that raise a single brood grow quiet. Woodpeckers fledge their young now. Pileated and hairy woodpecker fledglings are often heard or seen peeking out from cavity nests. Goldfinches begin breeding late in the month. Watch for them at forest edges, busy gathering thistledown for nests. Grouse chicks are learning to fly under the protection of shrubs.

Mammals

Cottontail rabbits and many other young mammals are on their own now and easy to spot. Now 1-2 months old, eastern coyote pups are learning how to hunt. Gray squirrels are in a second period of courtship and mating. The last of the red squirrels to mate during their winter breeding are now giving birth. The common little brown bat gives birth to a single pup. When nursing, a female bat eats her weight in mosquitos and other insects each night.

Plants

Along woodland edges and streams, elderberry bushes show their white or cream-colored blooms in wide flat heads. Chokecherries and purple-flowering raspberries are blooming along fencerows and rocky ledges. Mountain laurels are in full bloom on woodland slopes. In some areas, bowman's root may be flowering late. Look for white flowers with five long petals above tri-lobed leaves, or the red calyxes that remain after the petals drop.

Insects

The six-spotted tiger beetle (Cicindela sexguttata) is easily recognized along woodland paths and edges because of its brilliant metallic green color. Like other tiger beetles, this species has excellent sight, and its fast, zig-zag flight and landing pattern help in its predation of other insects. During mating, the male uses his mandibles to grasp the female's thorax.

Fungi

Among the numerous fungi emerging are two-colored boletes, variable russula, rosy russula, almond-scented russula, and common laccaria. Russula mushrooms have gills, are brittle in texture, and often have brightly colored caps. Lacking gills, bolete mushrooms disperse their spores from tiny tubes on the underside of the cap.

Reptiles and Amphibians

Listen at night for the long, resonating trill of grey tree frogs' mating calls. Box turtles and black rat snakes are now laying eggs. A box turtle lays up to 8 eggs in a hole dug with long claws on her hind legs. Black rat snakes lay as many as 12-20 eggs, usually under a decaying log or similarly protected spot.

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.