Woolly Bears in the Snow

“Woolly Bears in the Snow” sounds like the title of a fun children’s book. However, this month CNC received a call about a Woolly Bear caterpillar on the snow. Surprisingly it is not uncommon for CNC naturalists to receive calls in the late winter about caterpillars, cocoons or moths. Most frequently the calls are about giant cocoons that appear suddenly on top of the snow crust in February or March.

Moths and butterflies use a variety of survival tactics when faced with our frigid Midwestern winters. The most well-known is the 3,000 mile Monarch Butterfly fall migration. These *wise* creatures escape before winter turns brutal. But not all moths and butterflies undertake such an arduous journey. Mourning Cloaks prefer to stay right where they are, over-wintering as adults in the shelter of barns or tree holes. Other species of moth and caterpillar overwinter as eggs, pupa (chrysalis/cocoon) or caterpillars.

In the case of the Banded Woolly Bear, the caterpillar spends the winter dormant under the leaf litter beneath an insulating blanket of snow and ice. Dormant is a nice way to say that these tiny insects are equipped to survive freezing. They produce large quantities of glycerol, a cryoprotectant, which keeps their cells from rupturing when they freeze. In the spring the Woolly Bears become active, form a cocoon and metamorphose into the Isabella Tiger Moth (Pyrrharctia Isabella). A relative of our Woolly Bear, the Arctic woolly bear moth (Gynaephora groenlandica), actually has a life cycle that involves repeated freezing and thawing. Due to the harsh conditions in the Arctic Tundra, and the short growing season, it can take up to 14 years for the Arctic Woolly Bear Moth to grow from an egg into a moth. That is the longest life cycle of any moth or butterfly.

And what about those giant mystery cocoons that appear on the snow in the late winter? The cocoons are the over-wintering stage of a giant silk moth species. The most common in the Midwest are the Cecropia, Polyphemus, Promethea Silkworm and Luna Moths. These species only have one generation a year. The caterpillars feed on a variety of plants including trees such as box elder, cherry, birch and oak. In the late fall silk moth caterpillars weave large brown cocoons. The cocoons may be wrapped in group of leaves, attached to a branch or on the ground. In the spring a beautiful moth hatches out, but it will only live a few days. These moths do not even have mouth parts to allow them to feed. Their sole purpose is to mate, lay eggs and start the next generation of silk moths. In the late winter it is not uncommon for these cocoons to be dislodged from branches by the wind and weather

If you find a Woolly Bear caterpillar or a silk moth cocoon in the winter, do not bring it inside. If it warms up during the wrong season there will be nothing for it to eat, or in the case of the silk moth, no other moth to mate with. Odd as it sounds, the best thing for these amazing insects is to leave them out in the cold.

Wood Thrushes, Blackpolls and Windows

Later this month the Smithsonian Wood Thrush researcher will be returning to the St. Croix River Valley to relocate 25 gps-geotagged thrushes. These tiny Neotropical migrants travel over 3,000 miles twice a year on their spring and fall migrations. Already one geo-locator has been removed from a returning thrush that was captured during a routine banding session at Warner Nature Center. Wood Thrush populations have been declining by about 2% a year since the 60’s. This partnership research project aims to pinpoint where the thrush spend their winters, which will help when developing a species conservation plan.

In similar news, researchers have finally documented the INCREDIBLE journey that the tiny Blackpoll Warbler makes every year. Instead of migrating across land from northern Canada to Venezuela and Columbia, these small birds leave northeastern US and Canada and make a 1,400-1,721 mile non-stop flight across the ocean to arrive exhausted in Puerto Rico, Cuba and the Greater Antilles. And they only weight 12-13 grams. One of the researchers is quoted as saying “There is no longer any doubt that the blackpoll undertakes one of the most audacious migrations of any bird on earth.” To read more about the Blackpoll research visit The Boston Globe.

In late May I found a Wood Thrush dead outside a strip mall window in Hastings. This bird had traveled all the way to Costa Rica, or Mexico, and back, only to break its neck trying to reach the tree reflected in the store window. Neotropical migrants depend on safe winter and summer habitats, as well as critical migratory stop-over points in between. One of those stop-overs could be YOUR backyard. This June, as you clean your windows and fill your bird feeders, take a moment to evaluate your own backyard habitat. Can you plant more native species which can better feed and shelter native insects and animals? Can you modify your windows to keep birds from killing themselves in the reflective glass? Many window suppliers offer windows with screens on outside, such as those by Andersen Windows on Carpenter Nature Center’s Administration Building. For windows that don’t have external screens, the American Bird Conservancy makes window tape. Stop by this summer as we add the tape to more of the non-screened windows. Together we can make a difference for our songbirds.

Have you seen a Wild Ginger flower?

Have you ever wondered why some plants brag about their flowers by showcasing them at the top of the plant, while others covertly hide the flower under the leaves?

It all comes back to survival and in this case the importance of pollination. Wild Ginger grows along the shady trails in the woodlands at Carpenter Nature Center. During the spring its large leaves spring out the soil, hiding an intricate rusty red flower that sits at the base of the plant on the ground. The flower is bell-shaped and some people say it looks like a jug that has been knocked onto its side. This flower isn’t using UV maps to attract bees. Instead it is trying to attract small flies that emerge from the soil in early spring. These flies are interested in feeding on the thawing carcasses of animals that died during the winter. Although scientists debate whether or not the fly is the primary pollinator, the color of the flower does resemble decomposing animal flesh and the flies are observed entering the flower and getting covered in pollen.

During the summer the Wild Ginger’s seed matures. The seed has an elaiosome. An elaiosome is small oily food gift that is attached to the seed, which entices ants to take the seed and elaiosome underground where it will ultimately germinate and form a new plant. Native Americans and early settlers used the plant as a spice but researchers today believe it contains poisonous compounds. Wild Ginger was also used as a poultice to treat wounds, and modern science has confirmed the presence of two antibiotic compounds in the plant.

Bombus impatiens OR “the HUGE buzzing bee in my leaf litter

North America is home to over 4,000 native bee species, and one non-native, well-known European Honey Bee. You may have heard about declines in Honey Bee winter survival rates, but did you know that our native bees are also in trouble? In many study areas the variety of bee species and number of bees has decreased. The Rusty Patched Bumble Bee population has declined by 87%. The Franklin’s Bumble Bee hasn’t been seen since 2003. Native bees pollinate 80% of the top 100 crops globally. Plants and pollinators develop intricate symbiotic relationships, often resulting in specific pollinators being the only creatures to be able to pollinate a specific plant. If the pollinator goes extinct, so does the plant. Causes of bee declines include habitat loss, nest parasites, diseases spread from commercial bees, and chemicals.

What can you do?

Provide lots of bee food in the form of native plants with a wide variety that bloom throughout the year. Protect bee nesting habitat by installing artificial bee boxes, leaving bare soil for ground nesting bees and leaving dead snags for tunnel nesting bees. Use fewer chemicals of all types (pesticides, herbicides, rodenticides, etc). All these chemicals are, to some degree, toxic to plants, animals and our ecosystem. The suffix “–cide” means “to kill”.

One last note word of advice. This spring as you clean out the leaf litter in your garden, pay special attention to those residents who might have overwintered safely under the leaves. Queen Bumble Bees are the only Bumble Bees which overwinter. These matriarchs emerge from their shelter in the spring to buzz off and start a new colony. Early season gardeners may be surprised by the large, loud, buzzing bee but simply move to another area of the garden and leave that section until a little later in the season. A Queen needs her beauty rest after all.

Peregrine Falcons

The other day I was asked “How far will this Peregrine Falcon that is being released back to the wild migrate?” That’s a great question without a simple answer. Migration is complex as a bird needs to know where it is now, which direction it will go and where its destination is. Bird species use different navigation tools to migrate. There are species that use the sun, species that use landmarks like coastlines and rivers, species that migrate at night and use the stars, species that use olfactory cues and species that use the Earth’s Magnetic field which they monitor with tiny grains of magnetite in their heads that act as a compass.

Peregrine Falcons are found all over the world and of the 19 different subspecies many have different migratory habits. The “tundrius” subspecies nest on the tundra and will move an astounding 15,500 miles each year to spend winters in South America. The “anatum” subspecies generally spends the winter on its breeding grounds, unless they nest in the far north. This subspecies was once common across the Eastern United States but was extirpated by DDT. Through hard work and numerous partnerships, Peregrine Falcons have been restored in much of their eastern U.S. habitats. The young female Peregrine Falcon that was released looked like she was an ‘anatum’ subspecies. A logical guess would be that she’ll make some small seasonal movements and then try to set up a nest site in the Midwest in the next year or two. As she was banded with a federal band, plus a color marked alpha band, researchers may re-encounter her in the future and we’d all find out more about the life of this fascinating bird.