Final songs of summer

Post by Jen B

As summer winds down, a telltale hum that signals the changing seasons begins to ramp up in the fields and forests. These trills and chirps are the mating calls of tree crickets (Oecanthinae)—a group of fascinating insects that are often heard but seldom known or seen. Their small size and mint green color helps camouflage them amidst the verdant grasses, shrubs and trees of late summer.

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In order to create this chorus, males flip their broad wings up at a 90-degree angle to their bodies. Rubbing the ridges of their wings together rapidly creates chirps and long trills, which are often mistaken for frogs or cicadas. The sound frequency of these calls are unique to each species within a certain range, making it possible for females to pluck out the call of a potential mate from amidst the din. While mating, the female sips a secretion produced by a special metanotal gland, referred to as the “honey pot,” located under the wing on the male’s thorax. This fluid provides nutrients that increase the chance of successful reproduction; it is so coveted that females have been known to steal sips from other mating pairs.

two spotted tree cricketMale tree crickets use interesting methods to broadcast their calls to a wider audience. The two-spotted tree cricket (Neoxabea bipunctata) will call though a small hole chewed in a leaf to amplify its song (photo, left top). snowy tree cricket singingThe snowy tree cricket (Oecanthus fultoni) uses leaves as a baffle to increase the surface area of his wings, which increases the vibrato of his song (photo, left bottom). The staccato chirps of the snowy tree cricket are commonly heard in Lake County, Illinois. The chirping rate of this cricket increases and decreases as temperatures rise and fall. Scientists discovered that if you count the number of chirps in 15 seconds and add 40 you can calculate the air temperature in degrees Fahrenheit with surprising accuracy. For this reason, the species has another common name: the thermometer cricket.

Once the song is sung, the honey pot has been sipped and mating is complete, female tree crickets deposit eggs snugly into plant stems or tree branches. The surrounding plant protects the eggs through the long, dark winter and new crickets emerge as nymphs the following spring.

As autumn approaches, the hum of the tree crickets will grow a little louder before dulling to a whisper. Because these insects reside in a variety of habitats, they are heard in almost every Lake County Forest Preserve. Take the Hike Lake County Challenge this fall, or join us on a Walk with Docs and listen for these amazing critters while out on the trail.

Ghost of the prairie

Post by Jen B

Many years ago, while hiking through a prairie at dusk, I saw a stalk of delicate white flowers. They seemed to rise and hover above the surrounding plants like a group of little dancing ghosts. This was the first and last time I ever saw an eastern prairie fringed orchid (Platanthera leucophaea). Due to its dwindling numbers and hidden habitats, this rare plant has reached almost mythical status—a holy grail of sorts in the Midwest. We’re thrilled that this endangered native orchid seems to be gaining a foothold in the Lake County Forest Preserves, which are home to some of the largest remaining populations. Just this month, one of our restoration ecologists discovered an orchid in bloom (photo below). It was found at one of the preserves known to provide habitat for this species but is the first documentation of a population at the site.

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Adding difficulty to the search for this orchid is its idiosyncratic life cycle. The number of individuals in a population varies greatly from year to year with some years producing record numbers of flowering orchids and other years seeing few to none. Seed germination is reliant on a special relationship between the roots of the orchid and a soil fungus. This fungus provides nutrients to a seedling that can remain underground for years until conditions are just right. Eastern prairie fringed orchids can live in a variety of habitats from wetlands to prairies, yet they require full sunlight and little competition from surrounding vegetation to thrive. Research has shown that high precipitation levels and fire are two factors that promote flowering of these unique orchids. Blooms typically only last one week to 10 days.

orchidandmothEastern prairie fringed orchids have a jasmine-like fragrance that intensifies as night falls. The perfumed prairie air attracts this orchid’s pollination soulmate—night flying hawkmoths (a.k.a Sphinx moths, family Sphingidae). Each flower’s large lower petal has three fringed parts and a nectar spur. The spur is one to two inches long, tube-like and holds a sweet treasure for these nocturnal creatures with a perfectly match proboscis. When a hawkmoth inserts its proboscis for a sip of nectar, the orchid’s pollen sticks to it in a small bundle. The pollen is then transferred to the next orchid the moth visits.

Illinois historically contained the most extensive populations of eastern prairie fringed orchids. In 1927, botanist Herman Pepoon described the orchids as “a blanket of white on the moist, low prairie.” The threads of this “blanket” quickly unraveled due to many factors, including habitat loss, competition from non-native invasive plants, and over-collection by humans. The orchid’s dependence on just a few hawkmoth pollinators, which are vulnerable to habitat loss and pesticide use, has contributed to its disappearance as well.

orchid hand pollinationTo prevent this endangered orchid from becoming extinct, the U.S. Fish and Wildlife Service, land management agencies, research institutions and volunteer stewards have rallied to protect remaining populations. To protect the eastern prairie fringed orchid the Lake County Forest Preserves and dedicated volunteers:

  • Conduct an annual census of plants.
  • Control competing exotic plants.
  • Induce seed production through hand pollination.
  • Collect seed capsules.
  • Disperse seeds at sites deemed suitable for reintroduction.

Our monitoring and hand pollination efforts help ensure the viability of this extremely rare orchid species in hopes that it will not disappear entirely and become a true ghost of the prairie.

A beautiful invasion

Post by Kelsey Roehrich

I am a student at Iowa State University, and traditions are an important part of school life. One long-standing tradition centers around two swans, Lancelot and Elaine, which float on a small campus lake. Legend has it, walk around the lake three times with your significant other and you will be together forever, since it is said that swan pairs mate for life.

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Spring songs

In May the natural world of Lake County, Illinois clamors for attention. Frogs peep, toads trill, insects buzz and chirp, but the all-stars of the show are birds. Perching songbirds, referred to scientifically as oscine passerines, are known for their amazing and extremely varied sounds. For many small and secretive species, their calls and songs are often the only way to identify individual birds within the chorus.

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Shorter, non-musical bird calls are heard year-round. Calls are used in social interactions and as alarms. They are considered innate. However, scientists have determined that birds’ longer, melodic songs are learned in the first year of life. Birds use these spring songs, some containing several melodies, primarily in establishing territory and breeding. Continue reading

Wood frogs found!

Discovery is often about being in the right place at the right time. This is exactly what happened recently when a wildlife biologist for the Lake County Forest Preserves was in the right woodland on the right spring day. While monitoring wildlife, a biologist heard sounds from the elusive wood frog (Rana sylvatica). The duck-like breeding calls made by male wood frogs had not been heard in Lake County, Illinois since the late 1980s. This discovery is the first sign of victory following extensive habitat restoration and recent species reintroduction efforts.

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Crane chronicles

I am part of a volunteer group for the Annual Midwest Crane Count, monitoring the wetlands and fields in Lake County, Illinois each year for sandhill cranes. In the pre-dawn hours, our eyes scan for any hint of movement. Our ears listen for a bugling sound. Our mission: Determine the abundance and distribution of sandhill cranes (Grus canadensis) in the Upper-Midwest United States.

The arrival of these large elegant birds in Lake County is a harbinger of spring. More migrate through this region every year, and an increasing number are deciding to nest here as well. We know this thanks to the early-rising volunteers who help with the Annual Midwest Crane Count held each spring. This year, some of the first sandhill cranes returning to Lake County, Illinois were spotted in mid-March at Rollins Savanna Forest Preserve. Continue reading

Surviving in the subnivean

This winter has been harsh in Lake County, Illinois, causing many of us to wish we could migrate to South America like some birds do, or hibernate in a cozy underground den like the groundhog.  Alas, most of us just stick it out in the cold. It may offer consolation to know we are not the only animals active during these record-breaking cold, snowy days. It turns out there is a whole ecosystem teeming with life right under the snow.

Recently, scientists having been taking a closer look at life in the subnivean, which literally translates to “a place under the snow.” The space between the snow and the ground acts as a seasonal refuge for invertebrates, birds, and small mammals. Snow affords these small critters with remarkable insulation, and temperatures around 32 F regardless of the temperature above the snow. Biologist Bernd Heinrich explains the science underlying these insulating properties in the book Winter World: The Ingenuity of Animal Survival. “As long as both ice and water exist side by side, they constitute a thermostat keeping temperatures constant.” When water converts to ice crystals, heat releases. When ice turns into water, the process uses up heat.

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A snowy spark

Many years ago, while running along the Lake Michigan shoreline late on an evening in January, a feathered ghost appeared on top of a flag pole. It was the first time I had ever seen a snowy owl (Bubo scandiacus) and it stopped me in my tracks. This was the spark on that frozen night that lighted my fire of curiosity about birds. This winter, snowy owls have left their Arctic homes in record numbers, causing one of the largest irruptions (sudden increase) in northern Illinois in decades.

Although it seems natural to correlate the arrival of these boreal birds with the extremely cold, snowy winter northern Illinois is having, experts say the motivator is more likely linked to food. On their Arctic breeding grounds, snowy owls feast under 24-hour sunshine. Their food of choice is lemmings, small mammals with an extremely cyclical population. Bird expert Kenn Kaufman explains in a recent Audubon magazine article, that when the lemming population explodes, like it did last summer in northern Quebec, snowy owls have great breeding success, producing large broods of up to 11 chicks. As these chicks quickly grow into juvenile birds, the competition grows for the now dwindling numbers of lemmings. Thus, the young birds get nudged further and further away to find a meal, resulting in them moving to areas that mimic their treeless tundra home, such as the Lake Michigan shoreline. Continue reading

Restoring our woodland habitats

Post by Allison

The wooded habitats along the Des Plaines River in southern Lake County, Illinois are changing. Last winter, the Lake County Forest Preserves completed 194 acres of canopy and understory thinning in woodland communities at MacArthur Woods and Grainger Woods Forest Preserves. This winter, woodland habitat restoration has begun at Captain Daniel Wright Woods and Ryerson Conservation Area, in addition to continuing at MacArthur Woods.

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The restoration and species monitoring that will continue within these natural areas for the next 20 years will help ensure the sustainability of oak woodlands and the wildlife they support for many generations to come.

Winter visitors to these preserves, or vehicular passersby, will notice the use of heavy equipment, burning piles of brush, and an already visible difference in the openness of the woodland landscape. A number of canopy trees are being removed to increase the amount of sunlight reaching the ground. Visit these areas again when the leaves return, and early results of the Woodland Habitat Restoration Project will be obvious. Continue reading

Virtual camouflage hike

Leaves throughout the forest glowed gold against a backdrop of graying sky as I left Ryerson Conservation Area yesterday afternoon. This morning—as I entered the same preserve along the same road—the dark, skeletal branches were completely visible, stripped of their vibrant leaves that now lay in muddied piles on the forest floor.

These days of November mark a change from crisp colors to muted tones, which offer the perfect backdrop for animals to hide using camouflage. Lake County Forest Preserve educators often teach the concept of camouflage during environmental programs, where students hike in search of animal hides and mounts that have been hidden along the trail. Teachers and scout leaders, peruse our variety of school and scout programs to find a great fit for your group this year. Following is a virtual version of our camouflage hike. Continue reading