Halloween is coming, and we at Crossroads at Big Creek are noticing skeletons everywhere! But we aren't talking about holiday decorations. This time of year, we start noticing leaf skeletons, tree skeletons, bat skeletons, and, thanks to our resident coyotes, random skulls and bones scattered throughout our preserve.

As we pass the peak of color in the trees, our Wandering Wednesday hiking group will probably be looking at fallen leaves—some intact, but some looking like fancy, intricate lace. The caterpillars of several moth species are classified as "skeletonizers" because, at different stages of development, they feed on the juicy green tissue of the leaves. They do not eat the veins. Consequently, we find perfect skeletons of the leaves still clinging to trees or blanketing the forest floor.

Then, on Wednesday afternoon, participants of the Environmental Exploration activity, which is geared toward elementary students but open to learners of all ages, will observe "Leaves in the Creek," or at least the skeletal remains of them.

 In autumn, every leaf that drifts into the water infuses nutrients into the complex stream ecosystem. As soon as a leaf hits the water, food is leached from the tissues and quickly colonized by fungi and bacteria, which, in turn, provide carbohydrates and proteins for aquatic insects.

But then, the "shredders"… the leaf-eating aquatic insects such as caddisfly and crane fly larvae and herbaceous stoneflies eat the remaining tissue. The energy from last summer’s sunshine eventually passes through the food web to fish and other aquatic creatures, simply because in fall, leaves fall.   

Saturday Science (our weekend family program) will look at Tree Skeletons and will do a bit of forest forensics by examining the leafless branches of deciduous trees.

On the day before Halloween, the Environmental Exploration lesson will be on Bats! Even though we don’t have live bats to observe, we have the opportunity to examine the skeletons of these mammals. The inside bend of a bat wing is the elbow. The hook at the top of the wing is the thumb.

The other “fingers” function as bracing for the wing. The finger bones are sandwiched between two layers of skin. The skin is also attached to the hind legs at the ankles, and a very short tail is enclosed.

With this skeleton (essentially the same as that of a human--just longer fingers and shorter legs), bats can fly. And their flying ability is remarkable. 

While bats snap up insects with their mouths, they can also use their hands/wings or the membranes around their tails, which work rather like baseball gloves. 

The world has many kinds of bats. Understand that bats in Wisconsin do not suck blood. They do not pollinate flowers. They do not get caught in people’s hair.

Instead, according to the DNR website, “Bats in Wisconsin are insectivorous and are major predators of night-flying insects, including agricultural and forestry pests. “A single bat can consume up to 1,000 mosquito-sized insects in an hour, and a pregnant female can consume her weight in insects every night. It has been estimated that bats save farmers in North America over $22 billion yearly in [chemical free] pest control services.” 

So those are the bones of the Crossroads activities this week, but the Door Peninsula Astronomical Society will be sponsoring the “School's Out” program at 2:30 on Friday, October 25.  Open to all ages but geared to middle and high school students, the "Are We Alone in the Universe?" exercise is a good introduction to the DPAS Citizen Science Exoplanet research. Know (and share with promising young people) that the Astronomy Society hopes to mentor Door County pre-college students in this exciting research opportunity next summer.

Finally, our Monday afternoon adult program this week is a screening of the Wisconsin Public Television documentary Wisconsin Water from the Air.

 Wednesday, October 25

1:30 Wandering Wednesday

Join a naturalist-led hike through falling leaves and still green forests. It's easy walking and will take about an hour. Meet at the Collins Learning Center, Crossroads at Big Creek, Sturgeon Bay. Registration is not needed. The hike is open to the public and free thanks to our donors.

3:30 Environmental Exploration: Leaves in the Creek

This program, intended for elementary school students but open to all ages, will explore leaves in the creek, which provide an infusion of nutrients into the complex stream ecosystem. Dress for the weather. Meet at the Collins Learning Center. Registration is not needed. It is open to the public and free, thanks to the generosity of donors like you!

Friday, October 25 

2:30 School's Out Excursion: DPAS Sponsors: "Are We Alone?"

To interest middle and high school students in Exoplanets, the Door Peninsula Astronomical Society is sponsoring this activity in hopes of recruiting young people to experience authentic astronomical research during their pre-college years. This program is free and open to all.  Free and open to the public.  Meet in the Lecture Hall of the Collins Learning Center, Crossroads, 2041 Michigan Sturgeon Bay, Wisconsin 

Saturday, October 26 

2:00 Science Saturday: Tree Skeletons

The family Saturday Science (our weekend family program) will look at Tree Skeletons, and the indoor/outdoor program will include a bit of forest forensics as we examine the leafless silhouettes of deciduous trees. Meet in the Collins Learning Center, Crossroads 2041 Michigan, Sturgeon Bay.

Monday, October 28

1:30 Film Documentary  "Wisconsin Water from the Air"

Wisconsin Water From the Air" takes viewers above, atop, and along state waterways that inspire reflection, wonder, and adventure. From the routes that the Wisconsin, Mississippi, and St. Croix Rivers carve through the state’s landscape to the wide-stretching shores of Lake Michigan, celebrate the waterways that shape Wisconsin. Meet at the Collins Learning Center, Crossroads, 2041 Michigan, Sturgeon Bay.

Wednesday, October 30

1:30 Wandering Wednesday

Feel the crunch of fallen leaves and inhale the special scent of late autumn as you participate in this one-hour hike through the Big Creek Preserve. Free and open to the public. Meet at the Collins Learning Center, Crossroads, 2041 Michigan, Sturgeon Bay

3:30  Environmental Exploration: Meet the Bat

One of the quintessential Halloween icons, bats are an essential part of our Door County ecosystem. Geared to elementary students, this program on our favorite flying mammals is free and open to learners of all ages. Meet at the Collins Learning Center, 2041 Michigan, Sturgeon Bay.