Wildlife

by

Gray Tree Frogs

This tiny gray tree frog’s green camouflage helps hide it in nature. (All of the tree frogs for this post were photographed by my sister in her garden.)

Like tiny amphibious chameleons, gray tree frogs (Hyla versicolor) change color to match their surroundings. Sometimes bark-like gray or brown, at times a leafy green, and at others a mottled combination of color that mimics lichens or rocks, these tiny frogs elude predators through camouflage. Sometimes they even display a shade of creamy white or tan. No matter what color they exhibit, all gray tree frogs have bright yellow or orange marks under their thighs.

Why are they “tree” frogs rather than just frogs? All species known as tree frogs (or treefrogs) have large toe pads that enable them to climb trees, sides of buildings, and other structures. Climbing trees is all about catching the wide variety of food available there on warm summer nights: small insects and their larvae, spiders, mites, aphids, snails and even smaller frogs. At night gray tree frogs also climb sides of houses to perch on windows and capture small moths and other insects attracted to light. Because gray tree frogs are nocturnal, I often hear rather than see them unless they perch on the windows. What preys on them? Small mammals such as skunks, raccoons and opossums. Snakes, birds and larger frogs also eat them.

Artificial lights attract gray tree frogs in search of insects. This little one climbed the side of the house.

Gray tree frogs typically inhabit woodland edges and gardens near water. We’ve seen them at our cabin in rural Minnesota, and my sister, who lives in a Twin Cities suburb, has regulars that hang out in her garden. They pop up in damp places — the cat’s water dish, inside her garden watering can, under flower pots, on the patio furniture and in her small fountain. Adults are typically found higher up in trees or shrubs, while younger tree frogs are more terrestrial.

This tree frog’s golden color blends well with the potted plant.
Gray and charcoal hues help camouflage a tree frog on this weathered deck.

Unlike most frogs, the gray tree frog sounds more like a bird as it trills its one-note call. They breed from April to July and call most frequently during May and June, though it can be as early as April and as late as September. Females lay their eggs near a shallow pond or pool of water. Hatching and development takes about 7-8 weeks. They reach adulthood in two years and the average life span ranges from 5 to 7 years. Adult size is generally 1-to-2 inches (3-to-5 cm) in length.

Tree frogs hibernate on land, usually buried under leaf litter, fallen logs and other materials. Their bodies produce glycerol, which is converted to glucose. Large amounts of glucose in the frog’s vital organs acts as an antifreeze. Ice crystals will form in the body cavity and under the skin, but the lungs and heart are protected from freezing, and stop functioning until spring. Warm weather will thaw the frog and it will revive and continue its life. Gray tree frogs live in eastern North America from New Brunswick to Manitoba, south to northern Florida and west to central Texas.

Young gray tree frogs are often bright green.

Further Reading

Gray Tree Frog – Minnesota DNR

Gray Tree Frog – New Hampshire PBS

Gray Tree Frog – NatureWatch

by

September Hatchlings

Newly hatched snapping turtles (Chelydra serpentina) are half-dollar sized and usually charcoal or black in color.

September is hatching time — but don’t look to the trees for these babies: they are common snapping turtles! Every spring, in late May or early June, a large female snapper lumbers out of the Snake River, digs a nest nearby and lays between 20-50 (or more) round, leathery eggs. She picks a sunny location, and when she’s finished, she returns to the river to let the sun warm and incubate her egg clutch.

Three months later, the eggs hatch and the baby snappers dig their way to the surface. (We couldn’t locate the nest site this year.) Our neighbors, Ed and Melinda, who live year-round next to Pine County’s Snake River, say the snappers usually hatch on September 2nd. Some years there’s a slight variation; this year it was September 3rd and I was there to see part of it.

This hatchling still carries mud on its shell from recently leaving the nest.

The babies take off in several directions, but generally head toward the river or the swamp across the road often stopping to rest. It’s a slow, dangerous journey from nest to water for the half-dollar-sized hatchlings. According to the Minnesota Department of Natural Resources, between 60 and 100 percent of each egg clutch is lost to predators. Baby snappers are a favorite food of many woodland creatures, such as herons, fox, skunks, mink and raccoons. Once they reach the water, they are vulnerable to many other predators, such as fish, frogs, northern water snakes, some birds and other turtles.

The turtles moved slowly, many taking naps along the way. I lost sight of them in the tall vegetation on the riverbank. However, this little one popped out on the rocky shore.

Those who survive infancy take at least 5-to-7 years to reach adulthood. Most settle in quiet water with a muddy bottom, such as a pond, stream, marsh or slow-moving river. They feed on crayfish, frogs, small birds and mammals, insects and many types of aquatic plants. They also scavenge dead plants and animals, which helps to clean their aquatic environment.

As adults, snappers typically measure at least 8-to-14 inches across the greenish-brown carapace or upper shell, and weigh 35 pounds or more. They have one main predator: humans who hunt them for their meat.

The hatchling headed straight into the water. Notice the grass and seeds picked up during its trip to the river.

Snapping turtles are shy by nature. They are often docile if encountered in the water and will sink and swim away. However, on land they are vulnerable because they cannot completely retract into their shell. That’s because the plastron or lower shell is much smaller than that of most turtles. The smaller size makes it much easier for a snapper to move its head and neck, but provides less protection. If they are harassed and feel threatened, they may become aggressive, lunge forward and bite very hard.

Scientists believe that common snappers evolved in North America about 90 million years ago during the Cretaceous period. They outlived the dinosaurs and survived several ice ages. Today they populate North America from the Atlantic Ocean to the Rocky Mountains, and from southern Canada to the Gulf of Mexico. Humans are the main threat to their long-term survival. In addition to being hunted for their meat, many are killed by motorists during the nesting season when females and hatchlings cross roads moving to and from water.

The baby snapper began to swim upriver. It was not taken by predators while I watched it. I hope it will be part of the slim percentage that survives infancy.

To learn more about snapping turtles, check out these resources: Tortoise Trust, The Staying Power of Snapping Turtles, Common Snapping Turtle.

by

Pileated Acrobatics

The bush seemed too weak to support the pileated woodpecker’s (Dryocopus pileatus) size and heft.  Catbirds, robins, chipmunks and squirrels easily picked the ruby and purple fruit from the spindly chokecherry branches.  But, the crow-sized woodpecker struggled to alight and balance in the bush.  Its black forehead and mustache stripe identified this pileated as being a female. First, she flew straight into the bush, but the branches bent and sank under her weight.  Next, the woodpecker landed in each of the bur oak trees that flank the chokecherry and then dropped into the bush; still unsuccessful.

pileated5

When we returned to our cabin on the Snake River the following weekend, she had solved the problem.  Sometimes the pileated used her wings and tail to brace herself — even hanging upside down.  At other times, she seemed to pluck the fruit from midair.  The beauty of her wings unfurled in waves of ivory and black that thwacked the air.  Her red crest glowed like a flame in the bush.

pileated1

pileated4

pileated3

Though pileated woodpeckers primarily eat insects such as carpenter ants and beetles found in bark, they also eat a variety of berries and fruit, and sometimes visit our backyard suet feeder in St. Paul, Minnesota.

Chokecherry fruit (Prunus virginiana).

Chokecherry fruit (Prunus virginiana).

Our deck is just 6 feet from the bush, and if we were silent and still, the woodpecker payed no attention to us.  When I tried to photograph her she flew immediately.  As a result, I had to photograph her through the cabin windows, which reduced photo quality.

by

Nature: Looking Back at 2013

Snow, ice and cold blanket Minnesota now, but last June through October the woodlands bustled with life.  From unfurling ferns, to hummingbirds and harebells, to the changing Snake River and autumn woods in Pine County, MN, here are a few of nature’s simple gifts in 2013 that I recall with gratitude — and look forward to seeing again in 2014.  Happy New Year!

Trillium grandiflorum blooms at the base of a burr oak.

Large-flowered trillium (Trillium grandiflorum) and early meadow rue (Thalictrum dioicum) bloom at the base of a burr oak.

The maroon blossoms of Canadian wild ginger (Asarum canadense) lie hidden beneath its leaves.

The maroon blossom of Canadian wild ginger (Asarum canadense) lies hidden beneath its leaves.

Furled fiddleheads of an ostrich fern began to open.

Furled fiddleheads of an ostrich fern (Matteuccia struthiopteris) begin to open.

Canada columbine (Aquilegia canadensis) attracts hummingbirds in the spring.

Canada columbine (Aquilegia canadensis) attracts hummingbirds in the spring.

The Snake River flows high and fast through spring and early summer.

The Snake River in east central Minnesota flows high and fast through spring and early summer.

Yellow warblers are one of the most visible and vocal of our warbler species.

Yellow warblers (Dendroica petechia) are one of the most visible and vocal of our warbler species.

A web moth rests on the trunk of a red pine.

A woodland moth rests on the trunk of a red pine (Pinus resinosa), Minnesota’s state tree.

Ruby-throated hummingbirds are abundant through the summer and early autumn.

Ruby-throated hummingbirds (Archilochus colubris) are abundant throughout the summer and early autumn.

Bluets (Enallagma) are plentiful along the river in late summer.

Bluets (Enallagma) are plentiful along the river in late summer.

Delicate native harebells (Campanula rotundifolia) bloom into autumn and are loved by bumblebees.

Delicate native harebells (Campanula rotundifolia) are loved by bumblebees.

The Snake River runs slower in autumn.

The Snake River’s water level drops in late summer revealing basalt river rock.

Many different kinds of colorful fungi appear in autumn.

Many different kinds of colorful fungi appear in autumn.

Eastern chipmunks gather nuts, seeds and fruit for the winter.

Eastern chipmunks (Tamias striatus) gather nuts, seeds and fruit for the winter.

Native bladdernut seeds ripen in papery husks.

Native bladdernut seeds (Staphylea trifolia) ripen in papery husks.

Falling leaves settle among pebbles and add color to the riverbed.

Falling leaves settle among pebbles and add color to the riverbed.

A basswood leaf glows in the late afternoon autumn sun.

A basswood leaf (Tilia americana) glows in the late afternoon sun.

In late autumn, the river...

In mid-October, soft green, beige, maroon and brown color the riverbank.

Birch branches, bare except for their catkins, ...

Male catkins on a paper birch (Betula papyrifera) stand starkly against an early-winter sky.

by

Autumn Photos and Phenology

Seasonal changes happen quickly in Minnesota during October and it’s interesting to watch the progression into autumn. For example, swamp milkweed seed pods break open, male goldfinch feathers transform from bright yellow to olive green, chipmunks and other rodents stash nuts and seeds for the winter, and bees and most other insects have either died or are hibernating until spring.

Naturalists use the term phenology to refer to these changes.  Phenology is the study of the changes that occur in plants and animals from year to year — such as flowering, ripening of fruit and nuts, emergence or disappearance of insects, and migration of birds — especially the timing and relationship of these events with weather and climate.  It also can include other observations, such as the occurrence of the first frost, the date on which a body of water freezes, and when specific constellations are visible in the sky.  Here are a few examples of current autumn phenology that I photographed along the Snake River in Pine County, MN:

Northern red oak leaves begin to change color.

Northern red oak (Quercus rubra) leaves begin to change color.

Wild rose hips ripen to cherry red.

Wild rose hips (Rosa acicularis) ripen to cherry red.

Swamp milkweed (Esclepias incarnata) seeds pods release their silky seeds.

Swamp milkweed (Esclepias incarnata) pods release their silky seeds.

An eastern chipmunk collects acorns, hickory and hazelnuts in its pouches to store in its den for the winter.

An eastern chipmunk stuffs bur oak acorns into its pouches to store in its den.

Puffball mushrooms are common in autumn.

Puffball mushrooms appear in autumn.

Everyone who observes nature and records their observations contributes to the science of phenology.  If you’re interested in contributing your own observations, there are several organizations online, including:  “Nature’s Notebook” at the USA Phenology Network, the University of Minnesota’s Minnesota Phenology Network  and the National Science Foundation’s “Project Budburst”.