Acorn abodes

Post by Jen B

My family went on a bike ride last weekend at Ray Lake Forest Preserve. All afternoon, rain sputtered on and off as the clouds played tag with the sun. After climbing up a steep hill, the sky darkened again and we sought refuge under a canopy of large oak trees. One of my sons yelped,”Ouch! That raindrop hurt!” We quickly realized it wasn’t a raindrop, but a storm of acorns jiggled loose by the wind, plopping down on us. The trail became littered with acorns, and the kids began grabbing them. Upon inspection, the boys noticed tiny round holes in many of the acorns—evidence that these nuts were homes to acorn weevils (Curculio spp).

Acorns are a part of this weevil’s life cycle, serving double-duty for these little critters: food for the adults and a nursery for larvae. Acorn weevils are insects belonging to the family Curculionidae, commonly called snout beetles or true weevils. While their size is small, most measuring less than quarter of an inch, their numbers are mighty. Weevils are one of the largest families of insects worldwide.

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Weevils have an extremely long, hollow snout with tiny jaws at the tip. Antennae are situated halfway up this long mouthpart at an angle, so as not to get in the way during dinner. They use this unusual mouthpart like a drill, chewing in circles until the acorn shell is pierced.

Adult weevils are hard to find. They spend early summer days at the tops of oaks, feasting on the liquid fat and sweet nut meat inside young acorns. Want to see this process in action? Take a look at this amazing footage from National Geographic.

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A female weevil is careful not to eat too much from each acorn. Once she has gotten her fill, she lays a fertilized egg or two inside the acorn via the same hole. She then plugs the hole with a fecal pellet that dries and turns white. The eggs hatch a few days later into grub-like, white larvae with brown heads. The larvae feast and grow inside the acorn. As autumn arrives and the acorn rains begin, the weevils inside are signaled to make their move.

Acorn_GrubThey escape by chewing a hole (or enlarging the hole their mother made) and slowly squeezing their plump bodies out. Exiting an acorn can take up to three days, during which time the larvae are an appealing snack for small mammals, spiders and other insects. Those that successfully emerge will immediately burrow underground, where they spend anywhere from one to three years before emerging as adults.

Acorns abound this year, and autumn is a great time to explore the Lake County Forest Preserves in IllinoisPick up an acorn and see these critters, or signs of their presence, firsthand. Families will enjoy learning about acorns and other seeds along our new Trail Tales at Greenbelt Forest Preserve and Ryerson Conservation Area. The self-guided storybook trails offer nature education and exploration along with your hike.

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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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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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