Nature Blog

Ripples 11/14/19

Unlike many years, judging by the average daily temperatures, this winter was thrust upon us. It seems we missed out on those wonderful late fall days with temps in the mid-40’s when the woods are awash with colorful fallen leaves. They may return, but right now the world is prematurely snow-covered. A week ago, there was still a chipmunk under the bird feeder – I’m sure gathering seeds to be stored in its subterranean home for later snacking.  Now it’s gone – perhaps sleeping on top of its larder.  One wonders if such animals will feel the effects of the shortened gathering season later on.

photo of tree sparrow on branch

American tree sparrow

One always wonders about the birds, too, and how they manage to stay warm.  There are still some fall migrants around, like white-throated and song sparrows- hardy little birds which tolerate a lot of cold.  And tree sparrows are yet to come.  It turns out there are a number of things birds employ to stay warm in the winter.  

First, birds are warmer than we are.  Their body temperatures average 104 or 105 degrees F.  Combined with their generally smaller size and greater relative surface area, they have to work hard to maintain those temperatures.  Small birds like chickadees start shivering when the outside temperature is about 65 degrees. The movement of their muscles generates heat, and they will shiver the whole winter through.

We all know that birds have feathers – that’s one of the things that defines them. Feathers are amazing structures that give birds their streamlined shape, insulate them, repel water, and create displays to potential mates. How many feathers do birds have?  Small songbirds have usually 1,500-3,000 feathers that are molted and replaced as they wear.  The average bird has probably from 3,000 to 5,000 feathers. Large birds, like swans, have upwards of 25,000. Birds spend a lot of time tending and maintaining their feathers so that they function properly. They also molt and grow extra feathers in the fall.

Birds also have the ability to restrict blood flow to their legs and feet – preventing hypothermia.  Even though they can do this, watching ducks in cold water in winter still makes me shiver. The scales on their legs also help to prevent heat loss. Many owls, on the other hand,  have well-feathered legs to help them stay warm. Birds can fluff out their feathers, trapping air beneath them to provide extra insulation. On very cold days, this gives birds a puffy, swollen appearance.  

Birds  metabolize fat quickly.  They store calories taken in from the sunflower seeds that we put out as fat. They can draw down their fat reserves quickly, also. If one catches birds for banding, one can sometimes see the change in fat reserves on a bird from day to day if the same bird is re-caught.  

Some birds, including chickadees, go into a lower metabolic state at night called torpor. They aren’t actually hibernating – their metabolism drops just a bit, so they use less energy to make it through to morning.

Birds also adopt certain behaviors in winter- they find sunny places which are warmer and utilize dense vegetation to get out of the wind. (It can be significantly warmer under the boughs of a spruce tree, and some birds huddle together to share the warmth- chickadees are known to do that at night.)

The native trees and shrubs we planted help protect the songbirds in our yard during winter. The bird feeding area at Woodland Dunes is ringed with plants that shelter birds as they come in to feed. Offering high-quality foods like black sunflower, suet, and liquid water also makes things easier for birds in the winter.  They are ingesting good nutrition and spending less energy than required to obtain water from frozen snow and ice. Birds have the tools to make it through the longest winter, and with a little help from us will generally do just fine.

The first tree sparrow showed up at the feeders today.  Welcome back.

photo- American tree sparrow by Mdf from Wikipedia. 

Ripples 11/7/19

If you own a dog, you are assured to get outdoors in all kinds of weather and at all hours. I am one of those people and am sometimes less than thrilled at these excursions, especially when they happen in the middle of the night. At other times, I see things that I would not otherwise notice. I’ve written about this before, but I am so frequently reminded of the value of these little canine excursions that I think they bear further mention.

Lately, owls have been more apparent both at home and at Woodland Dunes. Even though they are not breeding this time of year, screech owls owls are calling and are more noticeable, perhaps because the nights are longer and I am outside more in the dark.  Actually, they never really seem to stop calling, but in summer seem to produce their quiet, tremolo call more than their full-fledged screech or whinny. Their eerie vocalizations are especially appropriate around Halloween, and I wonder what they think my little companion and me out for evening or early morning rounds. Great horned owls are vocal now too, as this is their courtship season. Theirs is a booming call that carries for long distances, with males calling at a lower pitch than females.

robin in snow

Any time that it’s not completely dark there are birds at or beneath the feeders – cardinals especially seem to be present when the light is low. Juncos are back, but there are still white-throated, song, and fox sparrows lurking in the weeds.

Lately, during the daylight hours, there have been robins everywhere, and it’s been that way for several weeks. This morning, despite the onset of another early-season snowfall, the very first bird to be heard was a robin, followed by a mallard duck. I live in a neighborhood with many crabapple trees which are wonderful sources of bird food. There are also thousands of common buckthorns – an invasive plant from Eurasia which also produces berries which birds consume. Eating buckthorn berries causes digestive problems for animals, to put it delicately.  The buckthorn berries and their seeds pass through the robins rapidly, so the birds are a great source of seed distribution for the invasives. And they seem to sprout everywhere. They must supply just enough nutrition to keep the robins in the neighborhood, at least until the real cold arrives.  Then the robins will move south just far enough to feel they can tolerate the winter, many just a few days flight south of here, ready to return when spring does. The less-hardy birds go to the Gulf coast  or even central Mexico. They are not the same birds as are the robins of Europe- those are smaller and lighter-colored members of the flycatcher family, while ours are thrushes.

We usually think of robins eating worms on the lawn, but there certainly won’t be any worms around here for those birds who choose to stay all winter.  Really, most of their diet consists of fruit and insects, although worms are certainly a favorite when available, conveniently right around nesting time. And all of those crabapples, berries, and bugs help to sustain a species whose numbers are estimated to be about 320 million birds, almost as many as there are people in this country. Unlike us though, they have to watch out for hawks, stray cats, and windows to survive.  

Seeing robins when the world is snow-covered is a treat, and even though we’re just starting winter, a sign of things to come.  In the meantime, I’ll appreciate their hardiness, and look forward to the next interesting encounter with them on these little but necessary walkabouts.

photo- American robin by the Weather Network

Ripples 10/31/19

The sun has come out, illuminating the soggy, white, crystalline world outside.  The first snow is retreating, and in a bare patch of sidewalk, moving very slowly, is a little wooly bear caterpillar.  They must be one of the hardiest insects and can be found moving around on mild days even in winter – apparently to upgrade their seasonal shelters.

photo of wooly bear and isabella moth

wooly bear and isabella moth

Banded wooly bears, or wooly bears, or wooly worms are so familiar, wearing their fur coats of black and brown. Their hairs are stiff, and might be irritating to the most sensitive of us, although they are not poisonous. They eat a wide variety of leaves from several tree species as well as asters and can be found almost anywhere there is vegetation.  They’ve also been know to be cannibals,  but we won’t get into that.

Wooly bears are really the larvae of the Isabella tiger moth, Pyrrarctia isabella.  The adults are beige-orange with a few spots, not a very noticeable moth at all. They produce two broods each year – the first in spring from the caterpillars that survived the winter. They then lay eggs to complete their life cycle in late summer. Those hatch into the wooly bears we see in the fall. These tough little caterpillars freeze solid in the winter, and their heart actually stops beating. They have enough stored energy to make it to warmer days when food is once again available.

The folklore surrounding the ability of the wooly bear to forecast the weather in the coming winter is interesting. It’s based on the width of the brown and black bands on the insect. The wider the brown band is, the milder the winter is expected to be.  What happens, in fact, is that as the caterpillar matures, the brown band becomes longer. If the fall is long and mild, one might see more caterpillars with broad brown bands, but if there is an early onset to winter, it will force caterpillars with smaller brown and larger black bands to seek places to hibernate. We would certainly already be aware if that were the case. Another story is that if winter is to be severe, the wooly bears migrate south to escape the cold. The ability to predict the weather has no scientific basis, however.

If wooly bears are threatened, they either scurry off at a fast pace or curl up into a ball and play dead – allowing one to pick them up for a close look (unless you are sensitive to them).  Even though they are common and constantly underfoot, they are interesting little creatures with 13 body segments, bristly hairs, and bright red-orange forelegs.  Adult tiger moths are known to produce sounds which interfere with bat echolocation, and the larvae are known to take up and concentrate substances from plants which make them unpalatable to predators so they have the ability to defend themselves.

As far as insects go, wooly bears, or Isabella tiger moths, are probably more appealing to people than most.  They are familiar, and share some of the same space with us, and probably survive despite some of the things we do.  Although we are now bracing ourselves for the coming winter, they are the ones whose lives depend on the shelter they find in these last golden days of autumn.

photo- from iNaturalist.org, caterpillar and adult Isabella tiger moth

Ripples 10/24/19

photo of a golden-crowned kinglet on a branch

golden-crowned kinglet

It seems to have been a wild fall so far and difficult to predict.  At the nature center, because so much of what we do depends on conditions outside, we’re very aware of what’s going on outside our door. The living things in our preserve, however, are remarkably consistent.

The wet year we’ve had has caused our staff to reschedule more visiting groups than I can remember.  Many classes of school children were either rescheduled or ultimately cancelled for weather-related reasons, despite our best efforts. Some of our trails that are normally dry were closed due to standing water and many trees came down from a lack of support due to soggy soil conditions. Our projects at the Manitowoc harbor and the Spirit of the Rivers have been impacted by both high lake levels and tremendous surf.  

Wildlife has to contend with all of this as well. Probably due to the wetness, there seemed to be a bumper crop of leopard frogs this year. They were on the trails and our lawn by the thousands.  They’re now gone to their winter shelter in ponds.  There were also an abundance of dragonflies and their relatives, and in later fall, there were many monarchs and painted lady butterflies, perhaps because our plants grew so well. Last week there were still a few painted ladies and autumn meadowhawks (small red dragonflies) to be found soaking up the warmth on the sunny days. There are still a few Isabella moth caterpillars (wooly bears) ambling around as well.

Migrating birds seem to be as consistent as ever in their timing- the early flood of warblers, orioles, vireos, and others who spend winter in the tropics has mostly come and gone, although a few warblers and even a hummingbird are still being seen in Wisconsin. They were followed by birds which don’t winter quite as far south, like the white-crowned sparrows and kinglets and thrushes. Now, the later migrants are arriving right on schedule: white-throated sparrows and juncos, blue jays, blackbirds,  and saw-whet owls,  and we’ll soon see tree sparrows and the winter ducks.  There also lots of robins still moving through, looking for berries as they wander. Some of those will probably decide to stay in sheltered areas throughout the winter. Their cousins the catbirds, still here last week, seem to have left us as well.

Our natural world is a canvas, with constantly changing images for most of the year. Those images right now are of colorful trees, frosty mornings, and traveling wildlife. I hope you have a chance to take a moment and appreciate the beauty around us here on the shore of a Great Lake.

photo- a tiny golden-crowned kinglet, a late season migrant taken by Nancy Nabak

Ripples 10/17/19

At Woodland Dunes we receive visitors from all over the world.  They often have a similar purpose for stopping by – they enjoy photo of a scissor-tailed flycatcher on a postnature, look for new places to experience its variety and find kindred souls with whom they can share what they’ve seen. We meet some very nice people, and some outstanding observers with a wealth of knowledge. We also experience wildlife, especially birds, from all over the Western Hemisphere.  Our 1,500 acres is preserved and managed for them, and once in a while something really special turns up.

Recently, Jessica, who runs our education programs, texted me about an unusual bird she saw on her way in to work, a scissor-tailed flycatcher.  Those of us who have visited the South-Central part of the country are familiar with these showy, long-tailed birds in pastel colors which perch on fences along the road from which they swoop out to catch grasshoppers and other insects. North and east of Kansas, it is unusual to see these birds, although a few do seem to wander each fall. This is not the first time one has been seen in our area – the last I recall was near a meadow right in the City of Manitowoc.

Nowadays, there are some wonderful tools for birders, one of them being a website run by Cornell University called eBird (ebird.org <http://ebird.org> ). Anyone can register and report bird observations, which are stored in an enormous database.  Millions of people contribute to eBird, submitting their observations which can be viewed by others – from casual birders to scientists. With so many contributors and observations, we can develop a more complete picture of what happens when birds migrate, and where rare birds are turning up. For very sensitive species, exact locations are often withheld for the safety of the bird.

In this case, we reported the scissor-tailed observation, along with a photo to show we weren’t making things up, which must have set off a bell somewhere because an alert went out shortly thereafter through other means and by the end of the day others were showing up to look for the bird. This continued for several more days until the bird presumably headed to a different location, perhaps one a bit warmer and more typical of it’s range. We have not seen reports of the bird since then.

How nice it is when we are treated to a surprise, in this case a beautiful bird not usually seen here. In this case we were lucky to have the bird visit us in the first place, have a staff member who recognized it, and means to let others know within a few minutes of its sighting. Like so many things, there is beauty around us if we have the interest and the motivation to look for it.  In this case, that beauty came complete with an extra-long tail.

photo: scissor-tailed flycatcher at Woodland Dunes by Nancy Nabak