Wisconsin Nature Notes

June: Cactus in Bloom and Osprey Chicks Hatch

In June, cactus is blooming, osprey chicks are hatching and birds are nesting in the prairie.

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Wisconsin Desert in Bloom

In June, Wisconsin’s “desert” is bright with color – this is the month when the cactus blooms.

Desert? In Wisconsin? Sandy soils along parts of the Lower Wisconsin River create a desert-like habitat. This “driftless” part of the state was never glaciated, but when glaciers to the northeast receded approximately 18,000 years ago, nearby glacial Lake Wisconsin drained and washed sandy sediments downstream to locations that later became dry prairie.

Much of this dry prairie is now gone, but at The Nature Conservancy’s Spring Green Preserve this rare habitat is protected. It is an arid place, reminiscent of the American West. The most visible evidence of that are the prickly pear cacti that grow in dense patches here.

The large, waxy yellow flowers of the prickly pear cactus only bloom for one day and then are gone, helping them conserve water, which is so vital in this dry environment. But while in bloom, they are abuzz with bees and other insects sipping nectar and pollinating the cactus in the process.

The best time to admire the prickly pear cactus is from June into July when their bright yellow flowers bloom and then wither, revealing pulpy, red fruit in late summer. Visit the eastern portion of Spring Green Preserve off Jones Road, park in the lot and walk the trail to the bluff face to see flowering cactus growing throughout the prairie.

Osprey Chicks Hatching

Osprey return to Wisconsin in mid-April, mating, repairing nests and quickly laying eggs by late April or early May. The adults incubate the eggs for an average of 38 days, with the osprey chicks typically hatching in the first week of June.

In 2013, 531 breeding pairs of ospreys nested in 55 of Wisconsin’s 72 counties. Nearly one-fifth of all nests are located in Oneida County, the hotbed of osprey reproduction. Historically, ospreys built their nests atop trees, rocky cliffs and other promontories, and even on a few islands free of mammalian predators. But today, more than 80 percent of the nests in Wisconsin occur on artificial structures and platforms, in particular on power transmission poles and cell phone towers.

Since these nests are often in plain sight, observations of the hatching and rearing of the chicks can be remarkably easy and enjoyable. The chicks grow quickly, fledging in less than two months. The adults frequently haul fish to the nest throughout the day, providing ample opportunities to watch their remarkable aerial skills.

Ospreys are the continent’s only raptor that eats almost exclusively live fish, so they’re truly expert at their craft. Several studies have documented that ospreys catch fish on at least one in every four dives, with success rates sometimes as high as 70 percent. The average time they spend hunting before making a catch is about 12 minutes, a figure human anglers can usually only dream about.

Ospreys typically circle and then hover over lakes in search of fish, finally diving feet first for their prey and plunging under the water. It’s a spectacular display, completed when the osprey rises from the water and straightens the fish out so it’s headfirst in its talons for maximum flight efficiency.

However, one complication often arises – eagles frequently watch the osprey’s successful catch and then swoop in to try and steal the fish, making for acrobatic aerial confrontations.

This drama occurs nearly every day over many northern Wisconsin lakes. One of the best places to see the action is at Wabikon and Riley lakes in Forest County where the shallow waters provide optimum fishing for ospreys and eagles.

Dragonflies Take Wing

June marks the first big hatches of dragonflies in northern Wisconsin, well-timed to help knock back the far larger hatches of mosquitoes. As common as their emergence is, few people have seen the amazing metamorphosis of an aquatic dragonfly into an adult, a phenomenon that occurs on nearly every Wisconsin lakeshore throughout the summer.

The nymph climbs out of the water onto a dock post, a cattail stalk, or sometimes just onto the shoreline, and then slowly breaks through its old exoskeleton. Its wings are like soft cellophane at first, but then the dragonfly pumps them full of fluid to expand and harden them until they eventually can sustain flight.

Dragonflies go straight from an aquatic nymph breathing through gills to flying, air-breathing adults, an amazing transformation.

Wisconsin supports 102 species of dragonflies, and the rarest of the family is the Hine's emerald dragonfly, the only dragonfly on the federal endangered species list. The insect's largest remaining population lives in Door County where coastal springs and wetlands provide rich habitat.

No one knows exactly how many Hine's emerald dragonflies are left, but the largest breeding population known to occur on the planet lives in twelve known habitats in Door County, with far smaller populations in a few locations in Illinois, Michigan and Missouri.

Hine’s emerald dragonflies live as aquatic larvae for up to four years before emerging as adult dragonflies. The larvae flourish only in streams, springs and wetlands fed by high quality groundwater. They first emerge in late June and live for only 2 to 6 weeks. After vigorous daylight feeding on mosquitoes, deerflies, flying ants and other flying insects, females return to water after mating to lay their eggs.

The Hine’s emerald dragonfly thrives in and around The Ridges Sanctuary in Baileys Harbor, as well as at The Nature Conservancy’s Mink River Estuary, Kangaroo Lake, and Shivering Sands preserves.

Grassland Birds Nesting

Many older Wisconsin landowners can remember a time when bobolinks, meadowlarks and other grassland birds were a common sight in Wisconsin. But as Wisconsin’s native prairies and savannas were plowed and converted to other uses, the populations of these grassland denizens declined precipitously.

The Nature Conservancy is working with a coalition of partners to preserve prairie remnants that are vital habitat for grassland-nesting birds in the Military Ridge Prairie Heritage Area, southwest Wisconsin. If you visit Military Ridge in June, you’ll see lots of bird activity. Males are still singing and females have begun to nest.

Some grassland birds like the Henslow’s sparrow are secretive and can be difficult to see, but bobolinks have a conspicuous hovering flight coupled with an “ecstatic and bubbling” song. The males are easy to recognize – their black head and belly, contrasting with their yellow nape and white rump is unlike any other songbird on the prairie. Bobolinks winter in Argentina, so their return to Wisconsin each spring to breed and nest requires an impressive journey of more than 5,700 miles.

Upland sandpipers are another bird you can see at Military Ridge – listen for their unusual “wolf whistle” call and look to the sky to spot them in flight. Upland sandpipers were once hunted extensively; now their numbers are declining due to the loss of their grassland habitat.

If we want to ensure that this “shorebird of the grasslands,” bobolinks and meadowlarks will be around to delight future generations of bird lovers, protecting Wisconsin’s grasslands is vital.

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