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

Robins and Apple Blossoms

Spotting a robin in March signaled the onset of spring to me as a child. We had a “Golden Book” titled, Birds: A Child’s First Book About Our Most Familiar Birds. It featured drawings of neatly woven nests cradling delicate eggs and portraits of familiar garden birds. Illustrations often showed robin nests built in blossoming apple trees and that image, along with the robin’s melodic songs, became synonymous with spring in my young mind.

Decades later, my husband and I bought our home in Saint Paul. Our first evening there, we sat on the back stoop beneath a beacon apple tree that’s now more than 80 years old. Two adult robins flew in and out of its leafy crown indicating the presence of a nest. A chorus of high-pitched chirps greeted the parents as the hatchlings anticipated dinner, their tiny heads stretching over the nest’s rim. During the next few weeks, we were privy to nestling squabbles, flight training, food procuring and the proper way to down a worm!

Some say that red-winged blackbirds (Agelaius phoeniceus) are the new sign of spring’s return to Minnesota. Robins now winter in the state and I hear their sweet songs on milder midwinter days. Many birds can withstand very cold weather as long as they find enough food to fuel their metabolic rate. Gardens often feature crabapple, mountain ash, dogwood and other fruit eaten by wintering birds. City boulevard plantings include fruit trees and larger trees like hackberry. I frequently see large groups of wintering robins dart between the crowns of boulevard hackberries near Saint Catherine University in Saint Paul. Robins also eat bird feeder food during winter that they wouldn’t touch in other seasons. Many a robin has dined with the woodpeckers at our suet feeder!

Sometimes I wake up to robin song drifting in through my bedroom windows in the predawn darkness. I remember childhood mornings of their pure, lovely caroling along with the scent of lilacs, the touch of humid air and perhaps thunder rumbling in the distance from an early morning storm. These are joyful memories — and though robins often ride out the winter in Minnesota, their clear singing, and the beauty of apple blossoms, still signify spring to me.

Further Reading:

American Robin

Red-winged Blackbird

Early Spring Native Flowers: Bloodroot

One of Minnesota’s earliest native wildflowers is bloodroot, (Sanguinea canadensis). Given its name, you might expect a scarlet or crimson flower. In fact, it blooms ice-white with a sun-gold center, though some emerge light pink. They look out of place, so stark and fresh among the remains of last year’s woodland growth and garden detritus. Its name refers to the toxic red-orange sap in the rhizome or root.

Each bloom emerges wrapped in a single curling leaf like a little blanket. The leaf remains curled until the blossom withers and then unfurls into a rounded leaf with a varying number of lobes. The leaves range in color from light green to blue-green depending on the plant’s age and condition. In its natural setting, bloodroot often grows along woodland edges, which provide sun in early spring and shade when the trees leaf out. In my garden, it grows along the edge of an arbor vitae hedge and under an ash tree. With shade and regular watering, bloodroot creates a pretty ground cover that lasts all summer under deciduous trees. If they aren’t watered during summer’s hot, dry spells, bloodroot leaves just go dormant until the following spring.

Native bees, honey bees and beetles pollinate bloodroot, which also can self-pollinate. Fertilized flowers form elongated capsules that enclose spherical seeds colored black, red, or brown. Here’s what’s special about bloodroot seeds: Each produces an elaiosome, an attachment containing lipids, amino acids and other nutrients. Attracted to these nutrients, ants carry the seeds back to their nests and feed the elaiosomes to their larvae. The ants either discard the remaining seed in a separate chamber of their nest, or toss it back out onto the ground. Either way, this process, called myrmecochory, helps ensure that the bloodroot seeds are dispersed for germination. Other spring wildflowers, such as violets, trilliums, hepaticas and Canada wild ginger, also form this mutual relationship with ants.

A member of the poppy family, bloodroot is native to much of eastern North America from Nova Scotia south to Florida, west to Manitoba and south to Texas. Native Americans used the plant’s red sap to make paint and to dye clothing, leather and other items. It blooms from March to May in Minnesota woodlands and was one of the first native wildflowers that I identified in the woods at our cabin years ago. The plants in most of these photos grow in our backyard. They hold special meaning for me because they were a gift from my aunt, who grew them under her trees for decades. They remind me of how she nurtured my love for nature when I was young.

Further reading:

Ants as Seed Dispersers

Friends of the Wildflower Garden – Bloodroot

Minnesota Board of Water and Soil Resources – Bloodroot

Wisconsin Horticulture – Bloodroot

Spring Happens All Around Us

On a recent morning, a friend looked outside and noticed the green blush beginning on trees and bushes. She recalled a teaching colleague’s comment during playground duty years ago. The colleague, a quiet woman of few words said, joyfully, “Oh, take a look! Spring is happening right before our eyes!”

Indeed it is. Thunderstorms, rain and mild temperatures coaxed baby leaves from their snug buds. They open like tiny green roses, flawless and smooth, not yet chewed upon by insects or mammals. Even on these cloudy, gray days buds and baby leaves paint the landscape in soft pastel greens and yellows. Don’t miss their fleeting, fragile beauty! They’ll quickly mature to full size and summer’s cool greens.

Maple Flowers

silvermapleflower1

In Minnesota, native maple trees typically flower before bees and other pollinators are active.

Spring’s earliest flowers are popping open: gauzy crocus clusters, squill — Siberian and striped — and snowdrops that have bloomed through snow, cold and high winds for a month. They are lovely, these Eurasian transplants that paint the earth with pockets of bright color. Our native blooms are more hidden and less showy, yet are beautiful in their unflowerlike forms.

Look up at the maple trees. Easy to miss high overhead, these blossoms are small, muted and less recognizable as flowers. Each emerges from a scarlet bud coat and glitters with golden, translucent filaments tipped in auburn pollen. They remind me of minute, single-celled creatures that we might see in a drop of water under a microscope, or of the tiny squiggly animals living on a coral reef — beauty suspended in air rather than water.

silvermaplecaron

Male flowers of the silver maple (Acer saccharinum) are packed with pollen for wind dispersal.

 

The female flowers of red maples (Acer rubrum) remind me of tiny coral reef creatures.

Oh, and even if we don’t notice the flowers overhead, if you are allergic to tree pollen, your “nose knows” that maples are blooming! Why do they disperse so much pollen? In most years, maples and a few other trees bloom before native bees and honey bees are active. The early-flowering trees depend on indirect wind pollination. Male flowers produce copious pollen to successfully fertilize female flowers on other maples.

Who Will Nest Here?

Black-capped chickadees, downy woodpeckers and white-breasted nuthatches recently explored this cavity in our apple tree.

Our beacon apple tree is pushing 80 years old. It’s dropped a few limbs over time; some splintered under the weight of apples, others weakened with age and rot. One old limb bears a small cavity. “So what?” you think —  unless you’re a chickadee, nuthatch or other cavity dweller looking for a nesting site. All three species frequently explore and tussle over this cavity, and I believe the chickadees are winning.

One sunny, frigid afternoon, a downy woodpecker pair ducked in and out of the cavity and were confronted and chased away by a black-capped chickadee. A curious white-breasted nuthatch also sidled over for a peek and was waved off by the chickadee. Later, three chickadees fluttered around the opening until two chased off the third. The remaining pair excavated and removed wood chips from the cavity interior; evidence they are preparing a nesting site! The male sings his territorial “fee-bee” (sometimes “fee-bee-bee”) song. I first heard him sing on December 31. 

One member of the black-capped chickadee pair (Poecile atricapillus) removes wood chips from the apple tree cavity.

Chickadees deposit excavated wood chips away from the nest site to avoid leaving signs for predators.

Will this pair nest in our apple tree? Black-capped chickadees prepare multiple nesting sites before the female chooses one, so we won’t know for a few weeks. Wherever they nest, the female will line the tree cavity with moss, soft plant fibers, feathers, hair and fur. She will lay 1-13 (usually 6-8) white eggs marked with reddish-brown spots. The female incubates the eggs and the male feeds her on the nest. Once the hatchlings are old enough to be alone for a short time, both parents feed them. Insects (including their eggs and caterpillars) and spiders comprise most of their high-protein summer diet. Black-capped chickadees also eat other small invertebrates, seeds, nuts and berries. They’ll visit seed and suet feeders in the winter. One cold afternoon, as I topped off our sunflower seed feeder, a cheeky chickadee landed on the edge of my filling-cup, snatched a seed off the top and flew into our arbor vitae hedge to either eat its treat, or cache it for another day.

Black-capped chickadees remain in Minnesota year round.  They are common in much of the northern United States and most of Canada.

I enjoy the chickadees’ curiosity, high-energy antics and their melodious breeding calls, especially as winter drags on. Stay tuned to find out whether or not they nest in our apple tree.

Further Reading

Black-capped Chickadee; Audubon Bird Guide

Chickadee Delight. The Sleepy Eye Herald-Dispatch. February 3, 2020.

Haupt, Lyanda Lynn. The Urban Bestiary: Encountering the Everyday Wild. (First edition). New York: Little, Brown and Company, 2013.

January Silence and Sound

Male cardinals (Cardinalis cardinalis) typically begin singing during mid-January in Minnesota. (I photographed this fellow on a sunny winter morning.)

The weight of winter silence presses on my ears. Heavy snowflakes drape tree limbs, topple seed heads and cover squirrel nests with a crystalline blanket. Falling snow absorbs the whir of auto engines, which pass almost noiselessly down the street. Even the incessant hum of the airport is muffled.

Suddenly, in the snowy hush a northern cardinal sings: “What cheer-cheer-cheer-cheer.” He repeats his joyful song four times and falls silent. His call momentarily illuminates the quiet. His red brilliance punctuates the black, gray and white of a January snowfall.

It is the first time I’ve heard a cardinal sing since last summer. In Minnesota, they typically begin singing in mid-January and will soon renew pair bonds and breeding territories. I welcome his upbeat melody that, along with the lengthening daylight, signals another milestone on the journey to spring.

Further Reading:

Northern Cardinal (All About Birds)

Northern Cardinal Minnesota DNR

Winter Crane Flies

Maple and basswood line the banks of the Mississippi River.

We hike along the Mississippi River as a cloudless sky, calm wind and a mild 52°F settle in for the afternoon. (The average high for Minneapolis-Saint Paul is 28°F today.) Blue jays, black-capped chickadees, and red-bellied woodpeckers call; gray squirrels rattle through the crisp fallen leaves. The river’s surface is unmarked by ripple or wave, and two Canada geese float a few feet from shore, honking softly to each other. 

Winter crane flies (Trichocera species) swarm and mate on mild winter days.

Wherever rays of winter sunlight stream through bare branches of basswood and maple, the air shimmers with small swarms of winter crane flies. The low December sun ignites their wispy forms into sparks of gold. They zip around as energetically as though it were July.

Most types of crane flies are abundant in summer. Just a few species mature and mate in the winter. The swarms shimmering in the afternoon sun consist mainly of males. Females join them briefly to mate, and then lay their eggs in rotting leaves and soil. When not in flight on mild days, the adults rest in protected areas such as hollow trees and caves. (What could they possibly find to eat during a Minnesota winter? Not much. In fact, adults typically don’t eat at all! The larvae eat rotting vegetation, fungi and animal scat.)

They sparkle like tiny gold jewels in patches of winter sunlight.

Winter crane flies are most common in late autumn, early spring and sometimes on mild winter days. Today, they never stray from the sun’s mild warmth — nor do we! A rare Minnesota December day, indeed, and one to remember when winter weather returns.

Further reading:

Winter Crane Fly (Family Trichoceridae)

Winter Crane Flies

 

 

November Honey Bees and Asters

A honey bee (Apis mellifera) nectars in asters (Aster novi-belgii) on a summer-like November day.

Two weeks ago, temperatures bottomed out at 15°F and a winter storm buried gardens, yards and colorful-leafed trees under almost 10 inches of snow. Now, sun and a week of daytime highs around 74°F have awakened chipmunks, spurred American robins to sing and enticed honey bees from their hives. The bees found our last asters of the season. In a sunny location, and protected by an overhanging arbor vitae hedge on the north side, the pastel blossoms continue to open despite the early snow and frigid cold. What a gift — a sweet treat for the honey bees and an unexpected return to autumn beauty for us.

October Yellow (Move Over, Red!)

 

It’s easy to focus on the “can’t miss” colors of autumn’s oaks and maples. Orange and red dominate October’s landscape.  But, look more closely: Yellow’s quiet beauty slowly swells from a few bright pockets of heart-shaped basswood leaves, to entire bluff-sides wrapped in lemon, butter and gold of birch, cottonwood, maple and hickory. Woods that were deeply shadowed and cool green just a few days ago, now glow on a sunny afternoon. The air smells good — earth, ripe seeds and the slightly tangy scent of aging leaves — all part of autumn’s final act before winter spreads its monochrome blanket.