Monthly Archives

July 2017

Friends of Retzer Receive Donation From Local High School

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In December 2016 we received a wonderful donation to the Friends of Retzer Nature Center from Waukesha West’s Interact Club. They held a fundraiser and we were chosen as their recipient. A check for $1280 was presented to the Friends from Patty Corrao (advisor) and Waukesha West students. We were very surprised at such a generous donation and will be put to great use with continuing support of Retzer Nature Center.

Also pictured are Friends Board members: Jerry Strom, Lyle Drier and MK Kelly.

Planetarium Premiers New Video System

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For 39 years, the School District of Waukesha’s Charles Horwitz Planetarium has been using slides for its basic form of media projection.  This fall, at Retzer Nature Center’s Apple Harvest Festival, the planetarium will celebrate the beginning of its 40 year with the premier of a completely new digital sound and video technology.

This entire $330,000 project was made possible by the generous donations of the Friends of Retzer Nature Center, the School District of Waukesha and the supportive public and private fund-raising activities promoted by the “Friends of the Charles Horwitz Planetarium.”

The planetarium’s new equipment called Digistar-6, will be combined with a new 7.1 surround sound system to transform the planetarium dome into an incredible immersive experience for visitors. Digistar-6 consists of a high-powered “host” computer and four, high-resolution “graphic processing” computers.  The 4,000 pixel presentation is made possible by sending the rendered graphic images through two new laser-phosphor video projectors.

Without leaving their seats, audiences can now trek through a rain forest, climb the heights of Mt. Everest, explore the depths of the world’s oceans or experience the weightlessness of space.  Beginning in September, a new library of school and public programs will be available.  For a complete list of programs, please see Waukesha County’s Environmental Guide, or visit the Charles Horwitz Planetarium website:

Parents, Tell Your Children: Fluttering, Flirtations, Fairies

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(Excerpts below are from an article on butterflies entitled, “Parents, Tell Your Children: Fluttering, Flirtations, Fairies” which was authored by Retzer naturalist Karen Mann and first appeared 30 years ago in the May/June 1992 “Center Line” issue. In this article, she aptly describes in detail the morphology, physiology, adaptation, reproduction and life cycle of butterflies.)

On behalf of Retzer Nature Center, I would like to acknowledge our appreciation to six families for their age old contribution. Most of us anxiously await their arrival: the Hesperiidae, Papilionidae, Pieridae, Nymphalidae, Rionidae and Lycaenidae, known together as the Order Lepidoptera (from the Latin “lepis” meaning scale and “pteron” which means wing). It is the scales, covering the wings of butterflies, which contain the pigments that give them their dazzling colors. Arrangement of the colored scales produces the distinct patterns used to tell individual species apart. These six families of butterflies account for roughly 18,200 species, including swallow-tails, sulphurs, skippers, metalmarks, angelwings, checkerspots, commas, and the gossamer wings such as hairstreaks, elfins and blues. Their secret to success (evidenced by their abundance and diversity) is their wings. The mobility afforded these animals allows them to establish large territories and breeding areas. This puts them in contact with the needed resources which provide them with food, cover and space.

Migration of butterflies offers an additional strategy for success. Flight allows butterflies to cover as many as 1100 miles in only a few days.

There is more to this success story. Numerous adaptations offer further points of study and observation. We can look further at wings. Butterflies communicate by means of their colored, patterned wings. Bright colors warn predators of the ill-effects associated with consumption of the butterfly’s sometimes poisonous body. (Many butterflies mimic the colors and patterns of poisonous or foul-tasting relatives to avoid predation themselves, however palatable they may be). Patterns such as owl spots or eye spots may frighten some predators away. Other patterns deflect a predator’s attack from vulnerable body parts to modified scales which appear antennae or tail-like.

Some butterflies confuse predators by folding up bicolored wings, hiding the brightly colored upper surface and exposing a camouflaged lower surface. These camouflage patterns blend with the host plants the butterflies often associate with. A bird may be attracted to butterflies’ bright colors. By folding up their wings many butterflies can quickly “disappear”, confusing the predators and saving their own lives. Another technique of camouflage is that of having transparent wings. Transparency allows the butterfly to blend completely with any background, since the background shows through.

Wings also function as a furnace. Butterflies bask in the sun on leaves, on the ground or on tree trunks. The colored scales absorb heat, warming muscles and nerves before flight. As the seasons change, successive generations of offspring produce varying shades of color. Lighter color in summer helps the summer-hatched; the wings reflect sunlight, which keeps them from heating up. In cooler weather, those hatched are darker, absorb more sunlight, and keep warmer. Some wing pigments are undetectable to humans (and other predators). These pigments reflect ultraviolet light which other insects can detect. This offers a mode of species-to-species communication, something like the flashing of mirrors used long ago.

Energy. A butterfly is a perfect example of what would appear to be a never-ending bundle of energy. Constantly moving, searching, fleeing, it burns energy, but from what source?

Butterflies are equipped with a long mouth structure called a proboscis. Usually coiled up under the head, this can be extended into flowers to probe for and extract the sweet nectar deep within. Few butterflies incorporate any form of protein into their diet. A few tropical species extract amino acids and proteins from seeds. Most burn the easily used carbohydrates derived from nectar. The proboscis is also used to apply saliva to dry surfaces. This dissolves salts left after evaporation, which are then consumed.

Reproduction in butterflies is as varied as are the species. The most significant communication between butterflies is that which is done for attracting a mate. Color is important in this. Males also have specialized scales (androconia) on their wings which dispense scent from glands within the wings. This scent rather intoxicates the female during courtship and mating.

When food is available and fat reserves are ample, the females produce eggs of varying, odd shapes and sizes. Over the course of their lives, females lay 100 – 500 of these unusual eggs. Patterns in which eggs are laid are just as diverse. Eggs hatch, and larvae emerge, more familiarly known as caterpillars. They proceed to gorge themselves, first by eating their egg shells and then by eating the leaves of the host plants they live on. As they grow, their skin tightens. They swallow air to puff themselves up. This causes the skin to split, and the caterpillar emerges. This process, called molting, repeats about four times. Caterpillars between molts are called instars. The final molt produces a hard outer layer, the chrysalis, Inside, the caterpillar changes to a butterfly. Although temperature and moisture trigger development, it is hormones that regulate this miracle of metamorphosis.

Adults emerge fresh, moist and crumpled. Soon after stretching and drying, they take to the air. They flutter about in search of a mate and a place to lay their eggs. They eat, do their best to escape predators, and, eventually, they die.

At least one Wisconsin butterfly species has already become extinct, the Xerxes Blue. Others appear on the Wisconsin Endangered and Threatened Species List, (endangered – Powesheik Skipper; threatened – Swamp Metalmark, Frosted Elfin, Regal Fritillary). As other animals are affected by destruction and manipulation of habitat, so are butterflies. Forests, fields, prairies, wetlands; butterflies have found a place in most habitats all over the world. These areas must be monitored and preserved, not only for butterflies but to maintain the balance of nature (with which we too are interconnected).

Our plans at Retzer include development of a butterfly garden in the area outside the existing greenhouse. The Waukesha Public Library has books available for those interested in starting their own butterfly garden. One of the most important factors to consider is to provide plants (for food and cover) for both caterpillars and butterflies. These might include pussy willow, lilac, phlox, butterfly weed, fernleaf yarrow, black-eyed susan, creeping St. Johns wort, cinquefoil, coreopsis, cherry, plum, dill and carrot. Planning is required to determine which species of butterflies are native to your area and which plants are used by them.

I invite you and your family to come and enjoy the company of these butterfly families.

Karen Mann

Bird Sightings (June 16, 2017)

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The following 36 species were seen during the bird hike on June 16th at Retzer Nature Center:

Orchard Oriole

American Robin

Red-winged Blackbird


Song Sparrow

Field Sparrow

Eastern Bluebird

American Goldfinch

American Crow

Eastern Kingbird

Northern Cardinal

Brown-headed Cowbird

Black-capped Chickadee

Northern Flicker

Sandhill Crane

Barn Swallow

House Wren

Tree Swallow

Clay Colored Sparrow

Chipping Sparrow

Savannah Sparrow

Henslow’s Sparrow


Blue Jay

White-breasted Nuthatch

Eastern Wood-Pewee

Indigo Bunting

Orchard Oriole male and female

Ruby Throated Hummingbird

Yellow Warbler

Gray Catbird

Common Yellowthroat

Rose-breasted Grosbeak

Turkey Vulture



Eastern Phoebe

Woodside at Retzer

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Shared by Woodside Elementary Teacher, Peter Dargatz.

The 2016-2017 school year marked the beginning of a creative collaboration between the staff and volunteers of the Retzer Nature Center and the nature kindergarten program at Woodside Elementary in Sussex. Over the school year,  eight experiences were split between the nature center grounds and the elementary school’s outdoor learning area.

Following the natural cycle of the seasons and connecting to the school’s curriculum, the students engaged in hands on experiential learning opportunities that built on prior lessons, culminating in a special nature celebration event in June where families were invited to the Retzer Nature Center to experience their child’s growth firsthand. Through parent surveys sent out by Woodside’s kindergarten team, the collaboration was very well-received by the families. Both staff at Retzer and Woodside look forward to not only continuing this collaboration, but hopefully expanding it as well.