Wisconsin Nature Notes

July: Crane Colts Flying and Green Frogs Calling

In July, crane colts are flying, regal fritillaries are dining on wildflowers and green frogs are calling.

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Sandhill Crane Colts Begin Flying

July is also a good time to watch one of Wisconsin’s largest birds raise its young. Sandhill cranes are big birds – more than five feet tall with a wingspan that can exceed seven feet. Their loud rattling, bugling call makes them easy to find. Look for them on grasslands and in open wetlands.

Sandhill cranes return to Wisconsin in March from their winter home in the southern United States. They nest in early April, laying one to two eggs on a nest of grass piled high on the ground in a marsh. The eggs hatch by mid-May, and the young begin flying in July.

Young cranes, called “colts,” are easy to recognize. Adult cranes are gray overall, with bright red foreheads and white cheek patches. Young birds are reddish-brown and lack the adults’ head coloration. The colts stay with their parents through the winter migration, then form separate flocks of juvenile birds the following spring. The young cranes do not begin nesting until they are two to seven years old – and they can remain with the same mates for 25 to 30 years.

Sandhills are the most numerous crane in the world, but that was not always the case. Unregulated market hunting and wetland destruction in the late 19th and early 20th centuries caused sandhill crane numbers to plummet – in 1936, Wisconsin’s entire crane population was estimated at just 25 pairs.

Unregulated hunting of migratory birds, including sandhill cranes, was eventually halted thanks to the Migratory Bird Treaty Act, and people began to appreciate and protect wetland habitat, which is critical for cranes.

In 2011, the estimate was 5,000 breeding pairs plus several thousand non-breeding juvenile birds in Wisconsin. The comeback of the sandhill crane is one of the great conservation success stories.

Sandhill cranes can be found throughout Wisconsin. A good place to see them is the Conservancy’s Lulu Lake Preserve near Mukwonago.

Aquatic Flowers Brighten Northern Lakes

Northern Wisconsin is world-renowned for having one of the highest lake densities in the world. In Vilas County alone, some 1,300 lakes cover 17 percent of the land surface, with wetlands blanketing another 18 percent. So, when aquatic and wetland flowers come into full bloom in July, it can be a riot of color.

Shoreland flowers abound along the water’s edge, in the reds and purples of marsh milkweed and blue flag iris, the orange of jewelweed, the white of water hemlock, and the blue of blue vervain. Emergent flowers like pickerelweed, arrowhead, and wild rice clothe the shallows, rising above the surface of the water. Floating-leaf plants like white and yellow water lilies, watershield, and smartweeds inhabit a little deeper water. And some aquatic plants like the yellow flowers of common bladderwort just loosely float around, rootless but beautiful.

In the bogs, pitcher plants and sundews have come into flower, too. The single nodding, deep burgundy flower of the pitcher plant is quite unusual, looking a bit like an upside-down, star-shaped umbrella.

Perhaps most beloved of the aquatic flowers are white water lilies, which smell to many like fresh oranges. One historical use of white water lilies was as a love potion. For the love potion to work, the flowers had to be picked during a full moon, though the pickers had to wear earplugs to prevent being bewitched by the local water nymphs. The dried flowers were then worn as love talismans.

An exceptional area to explore for aquatic flowers is The Nature Conservancy’s Catherine Wolter Wilderness Area near Boulder Junction with its 36,000 feet of undeveloped shoreline on 15 wild lakes, and its many associated woodland ponds.

Green Frog’s Twang Attracts Mates

In July, male green frogs sing just about every night from the shallow waters of our lakes and rivers, hoping for female companionship. Their call, usually described as something like strumming a loose banjo string, wouldn’t seem attractive, but music is truly in the ear of the beholder.

Most of the singing will come to a close once the females choose their mates, apparently preferring males with territories that include lots of submergent plants, which provide a mat for her eggs to lie upon. She’ll lay 3,000 to 5,000 eggs, each tiny, black egg embedded in a filmy, foot-wide egg mass.

A Wisconsin Department of Natural Resources study looked at the effect of lakeshore development on green frog distribution and abundance in northern Wisconsin. The study found that green frog numbers were greatly reduced on developed lakes. The decrease was directly related to the reduction and fragmentation of optimal green frog habitat.

Their depletion in numbers is important, because like the proverbial canary in the coal mine, the green frog can serve as an indicator of the health of aquatic life in northern Wisconsin lakes.

Green frogs and bull frogs are usually the last frogs to sing over the course of the summer and will gradually grow silent, leaving late July often eerily quiet.

To hear green frogs in all their twanging virtuosity, visit undeveloped lake shorelands like those at The Nature Conservancy’s Caroline Lake Preserve near Mellen or Wabikon Waters and Woodlands near Crandon.

Regal Fritillaries Nectar on Prairie Flowers

Blooming summer flowers on the prairie attract butterflies, and among Wisconsin’s most impressive butterflies is the appropriately named regal fritillary.

These are large, conspicuous butterflies that fly slowly from flower to flower, gathering nectar from plants such as milkweeds, thistles, sunflowers and blazing stars. Their bright orange and black wings, nearly four inches across, are hard to miss. They live only a few months, typically from late June to early September. July is an ideal time to look for them on Wisconsin’s prairies.

But regal fritillaries are alive on the prairie at other times, too – as caterpillars. Come August, the big butterflies lay their eggs on the prairie’s violets. The eggs hatch in the fall, and the tiny larvae crawl into the leaf litter where they remain dormant through the winter. They emerge the following spring and feed on the violets’ new leaves. By late June, the caterpillars have completed their metamorphosis into butterflies.

Regal fritillaries are dependent on these prairie violets for their young, so fewer prairies mean fewer fritillaries. They are listed as endangered in Wisconsin. A good location to look for regal fritillaries in July is the Military Ridge Prairie Heritage Area near Barneveld.

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