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Northwoods Phenology Blog

phenology [fəˈnäləjē] NOUN: the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.  

November 2022: Wild Rice & Native Cranberries
By Carrie Rasmussen, Philanthropy Director

Wild rice along the Manitowish River (Photo by Ron Eckstein)

Manoomin, the Ojibwe word for wild rice, is a food staple of northern tribal members and a centerpiece in their cultural traditions. It is concentrated in northern Wisconsin and northern Minnesota. Wild rice is an important food source for animals as it has a high protein content. It also provides habitat for many bird species, especially waterfowl that also use it for nesting cover.

Wild rice reproduces as an annual seed and goes through a submergent stage before floating and surfacing and then developing flowers and seeds that ripen in late summer/early fall. It grows best in lakes, creeks, and rivers with areas of shallow water between 1 – 3 feet deep atop soft, organic muck. Each spring the seed needs to germinate and grow while competing with other perennial aquatic plants like white and yellow water lily and water shield.

Wild rice seeds can withstand long, cold winters with periods of lake ice (and can actually survive well when ice freezes right down to the lakebed in shallow bays). Most perennials are set back by these same harsh conditions. Over the last 20 years our northwoods winters, on the average, have been milder than normal, with much shorter periods of lake ice. Mild winters give perennials a boost while setting back wild rice. Wild rice has suffered a slow, region-wide decline and perennials have flourished.

Wild rice marshes along the Wisconsin River

Wild rice faces other challenges. It also depends on a short growing season, yet warmer average summer temperatures are doing the opposite and are extending the growing season.  This is a shift that favors other aquatic plants, including invasive cattails. Warmer, more humid conditions also spur growth of fungus, such as brown spot disease, that can kill the rice plants. More frequent and intense rainstorms that cause flooding of streams can damage wild rice beds by uprooting and killing young, immature plants.

Shallow marshes could lose their native wild rice populations in the future in the absence of suitable habitat due to changes in northern Wisconsin’s temperature and precipitation patterns. The Great Lakes Indian Fish & Wildlife Commission’s Climate Change Vulnerability Assessment shows that wild rice is highly to extremely vulnerable. In fact, it is the most threatened species out of 60 in the report because of numerous climate-related and human-caused threats (see pages 28-30 in the report).

Listen to the WXPR Feature “A Shifting Wisconsin: Local Extinctions, Migrations, And Culture in The Face of Climate Change”

Another native food crop, the cranberry, is also facing an uncertain future. Wisconsin is the #1 producer in the nation and the world. The fruit contributes greatly to the economy and is tied to our identity (it is Wisconsin’s state fruit).

Wild cranberries at Tower Nibiiwan Conservation Area (Photo by Kathy Noel)

Climate change is believed to be impacting yields of cultivated cranberries.  With the swings in weather conditions, severe rain events and milder winters, fruit production is being impacted. Researchers at the University of Wisconsin – Madison are making slow but steady progress studying how cranberries adjust to changes in seasonal conditions. They are interested in learning how cranberries survive during our deep, freezing temperatures in winter, as well as during high summer temperatures during the growing season. They want to find certain cultivars that have the traits that make them most adaptable and able to withstand climate change. Once they identify the specific molecular mechanisms that allow certain cranberry cultivars to withstand change, they can then cross them with types that have strong fruit production, resulting in a high-yield and highly resilient cranberry. Let’s give thanks to our native crops this and future holiday seasons.

Learn how NWLT is addressing climate change.

Listen to Wisconsin Public Radio’s “How Climate Change Affects Wisconsin’s Cranberries”
Read the Wisconsin Energy Institute’s “Climate Change Is Making the Future of Cranberry Growing Uncertain”

August 2022: Don’t Delay in Learning About the American Marten
By Carrie Rasmussen, Philanthropy Director

In parts of ten northern counties in Wisconsin lives the American marten (Martes americana), a solitary, but curious member of the weasel family, often mistakenly still referred to as the pine marten.

The American marten population has been recovered, to some extent, since they were extirpated from the state in the 1920s due to unregulated trapping and extensive habitat loss from logging. The last two past reintroduction projects occurred in 1975-83 and 1987-90, successfully establishing breeding populations in parts of the Chequamegon-Nicolet National Forest.

Still, the American marten remains a state listed endangered species, and it’s not clear to wildlife biologists why they have failed to expand their numbers and ranges here. It’s thought that perhaps because its primary competitor, the fisher (Pekania pennanti), has a significant overlap niche, so competition between the two species may be delaying the recovery of martens.

American marten in down mature yellow birch tree cavity. By Zach Wilson

Recently, I stumbled across the fact that martens mate in our northwoods in early to mid-summer, but no kits are developing in the females’ wombs yet. A reproductive quirk known as delayed implantation, or embryonic diapause, is a characteristic of martens, fishers and other weasels.

According to the WDNR, “Although the female marten’s eggs are fertilized by mid-summer, they don’t fasten to the wall of her uterus until January or February. The fetuses then develop quickly; young are born in late March or April, nine months after fertilization. The female makes a den in a hollow tree, stump or rock crevice, lines it with leaves, moss and other vegetation and gives birth to 2- 4 kits.” They are weaned at 6-7 weeks old, then mom soon leaves to mate again. Kits are almost full-grown when three months old, and then they disperse from their home territory to establish ones of their own.

Knowing that the Northwoods Land Trust’s (NWLT) Sack Lake Hemlocks Conservation Area in Iron County has suitable habitat – plenty of mature mixed conifer-hardwoods- there’s a strong likelihood that American martens hunt and den there. Zach Wilson, Conservation Specialist with Iron County, thinks so. Zach recently presented on the topic of the American marten at NWLT’s 2022 Annual Meeting and many of his studies take place across the street from Sack Lake.

Study of the American marten in Iron County. By Zach Wilson

His enthusiasm inspired me to learn more about this mammal that needs our help to survive, as they depend on mature and old-growth forests, which are hard to come by. Less than one percent of old-growth forests exist in Wisconsin today. If more private landowners and conservation groups in the northwoods manage land to transition to old-growth, martens would benefit.

Check out Zach’s short video of an American marten in a mature cedar tree cavity. Hopefully the video and images will cause you to stir up some interest in learning more about this cute but fierce creature.

Don’t delay in offering your support to NWLT’s permanent land conservation programs! It is one way you can play a role in protecting Wisconsin’s endangered American marten.


June 2022: Our Great Wisconsin Birdathon Story
By Frank Schroyer, Land Conservation Associate

It isn’t everyday your organization gets to spend time out and about searching for birds while raising money for conservation. A fall 2021 meeting with Wisconsin DNR staff brought to our attention the Great Wisconsin Birdathon, the state’s largest fundraiser for birds. Funds raised are added to the Natural Resources Foundation of Wisconsin’s Bird Protection Fund and participating non-profits, like the Northwoods Land Trust (NWLT), get to keep 50% of funds raised to support our own missions. Naturally, myself and some of the other bird nerds around the office decided this event would be a fun, simple way to raise a little bit of money, and of course to get out birding.

Bluebird by Bev Engstrom

Traditionally, participating Birdathon teams select a single day between mid-April and June to complete a big day, where you spend a 24-hour period trying to find as many bird species as possible. Some teams will bird throughout the entire state, and others will confine their search to a single preserve. We decided to do something in between, and bird across the northwoods at some of our favorite hotspots. Next, we picked May 24th as our big day date. Choosing a day slightly later in May would ensure the bulk of migration was underway, and the greatest number of species would be present to find. Our team name, NWLTurkeys, was decided at our spring board of directors’ meeting, primarily because it produced the most laughs when presented. Details were ironed out closer to our big day, and a total of four staff and two board members committed to participating.

We were all up bright and early, heading to different areas to try dividing and conquering. Early morning (before the sun comes up) is the best time of day to listen for birds that are the most active at night, such as owls, woodcock and snipe, and several different kinds of secretive marsh birds. Between Lower Ninemile Lake, Thunder Lake Marsh, and the Little Turtle Flowage, we felt we had our bases well covered. Our team did end up finding American Bitterns, Sora, and Virginia Rail in the early morning hours. Other highlights from the morning included an excellent number of warbler species (21!), wrens, hawks, woodpeckers, and a few Barred Owls giving a “goodnight (good morning?)” hoot. As the day continued our team stayed in touch with each other to give updates on fun findings. By lunch, we were already over 100 species for the day!

Big days can be quite the grind, and the usual burnout time is high noon. Our team pushed on to scrape together a few more species for the day throughout the afternoon and early evening. We ended the day having found 127 different species! Some of the highlight birds were Grasshopper Sparrow, Red-headed Woodpecker, and a gregarious Tennessee Warbler. At the end of it all, we decided the day, and Birdathon, were a smashing success for our inaugural year. The NWLTurkeys also surpassed our fundraising goal of $1000! We are so excited to do it all again next year and hope to use 2022 as a springboard for many more Great WI Birdathons.


April 2022: Early Spring Frog Blog
By Ron Eckstein, NWLT board member

Spring in the northwoods is late this year. Just yesterday [April 12] snow blanketed the forest floor and the small wetlands were frozen around the Rhinelander area. After a heavy overnight rain, the snow disappeared and the small,
¼-acre wetland near our house began to thaw and is about 5% open water now.

Wood frog (by WI DNR)

I’ve been recording frog phenology at my little wetland for more than 20 years. I listen every night just after dark. The first one or two frogs I hear calling will be a wood frog or a spring peeper. This will happen when the water temperature hits 50 degrees on the north and northeast edges, where the sun gets a good grip. Those one or two frogs will call when there is still ice on southwest corner of the wetland. They are impatient.

As soon as the ice is gone and the water temperature hits 50 degrees the wetland will explode with a full chorus of wood frogs and spring peepers. The evening full chorus of wood frogs will last only 6 to 10 days then drop off the nothing. The full chorus of spring peepers will continue into mid and sometimes late May.

Spring peeper (by WI DNR)

In most years the spring peeper chorus will be very loud, intense. It is a signal that spring is finally here and we can open a bedroom window and fall asleep to the peeper’s lullaby.

To learn more about Wisconsin’s frogs go to: https://wiatri.net/inventory/frogtoadsurvey/


February 2022: Love is in the Air
By Troy Walters, NWLT Outreach & Education Coordinator

As I am writing this, Valentine’s Day is fast approaching.  Of course, we are not the only species that is using February to celebrate love.  Bubo virginianus, or great horned owl, is the earliest nesting year-round avian resident in Wisconsin.

Orion, the Great Horned Owl

When I used to work with an education great horned owl (Orion) at Trees For Tomorrow in Eagle River, WI, I would oftentimes hear him calling back and forth with another great horned owl on campus.  His lower pitched “hoo-h’HOO-hoo-hoo” was alternated with his female friend’s distinctly higher pitched voice.  This is because even though females are slightly larger than males, the smaller male has a bigger voice box, or syrinx.  If Orion would have been out of his mew, they would have gotten closer until next to each other, likely bowing with drooped wings, mutual bill rubbing and preening each other (called allopreening).

After mating, 1-4 eggs are laid, with each egg laid more than a day apart, and incubation beginning after the first egg for 30-37 days.  This means that the first egg laid will be the first hatched and have a decided advantage in getting more food, growing faster, and therefore have the highest likelihood of survival in lean years.

Normally by March, great horned owl owlets are begging for food with a loud scream that people don’t normally associate with an owl.  Owls can make many other noises, one of the most common being bill snapping in response to stressful situations.  Orion was known to do this quite often and was a good way to communicate to me that he did not like what was happening at that time.

Great horned owls generally inhabit areas that have some sort of “openness” to them in the form of a less dense forest understory or forest near an opening like a field, wetland, or pasture.  They can also be found in cities living in wooded parks and places like cemeteries (where I saw my first ever great horned!).

The Holmboe Conifer Forest in Rhinelander, owned by the Northwoods Land Trust, is likely a great place to hear and see a great horned owl.  If you are walking there during the day, perhaps the easiest way to find one is to listen for other birds making a ruckus, especially crows.  The behavior of smaller birds gathering together and harassing larger birds is known as mobbing; in this case many crows around the owl.

It is not very likely you will hear this owl flying, as their soft frayed feathers and a comb-like leading edge on the first primary flight feather makes for stealth flying.  If you do see them flying, I always say they look like a flying 4×4; blocky appearance with short, wide wings that allow for maneuverability and enough lift for their three-pound body.   It was such a treat working up close with such a powerful raptor that is so much like us in many ways.  I hope you are able to find one during a winter jaunt out in nature, possibly along the trail at the Holmboe Conifer Forest.

To learn more about Great Horned Owls and to hear their calls, visit the Audubon Field Guide online


November 2021: Deer and Hemlocks
By Frank Schroyer, Land Conservation Associate

The white-tailed deer (Odocoileus virginianus) is an iconic species in the Northwoods of Wisconsin. Our area is renowned worldwide for the limitless opportunities to see these ungulates. Now, with the earliest signs of winter showing in the woods in November, I find it odd when I do not see a single deer on my commute to and from work. They are moving a lot this time of year, anxious to put on fat and take full advantage of the rutting season before true cold and snow hit.

Often when I think of deer, I find my mind eventually works its way to thinking of eastern hemlock (Tsuga canadensis) as well. During the turn of the 19th century the expansive hemlock forests in the upper Great Lakes region, prized for their usefulness in the tanning industry, were largely cut during massive logging operations. Nearly 99% of hemlock forest was lost during this time.

It was anticipated that after the decimation of hemlocks, they would recover over a period of time. That has not happened, and in the 70s and 80s scientists began to wonder why. What became clear through many years of research is hemlock requires some very specific conditions to grow, and saplings face many obstacles to reach maturity, the most impactful being deer browse.

Hemlocks germinate best in well-shaded, moist, mineral rich soils or other coarse woody debris (dead trees). Saplings can take up to a hundred years to reach canopy level heights, and may only grow a few meters tall in the first few decades of life. Maturity is especially difficult to achieve in the presence of herbivory.

White-tailed deer have been shown to be highly impactful on vegetation and forest ecosystems as a whole. Now present on the landscape in numbers 2 to 5 times more dense than pre-European colonization, deer are having greater impacts than ever before. In fall and winter, they will often seek hemlock saplings as a source of food, resulting in high mortality rates among these young trees.

At the Holmboe Conifer Forest in Rhinelander, Northwoods Land Trust had a deer exclosure installed to combat herbivory and promote hemlock growth. These fences help to keep deer out of areas where regeneration is occurring, or is very likely to occur. By preventing saplings from getting mowed over by deer, we lend a helping hand to hemlocks and help create mature trees which can then produce more cones and seeds.

So, take a walk around your property this month, and look around for hemlocks or other susceptible conifers such as Canada yew. There may be areas where you too can install some fencing to keep deer out while the evergreen saplings make their long journey upward.


August 2021: Invading Earthworms

During the height of the open water fishing season, the topic of invading earthworms for this summer blog post is really relevant. If you unaware of how earthworms have impacted our soils in the northern forests of Wisconsin, you must read further!

Pennsylvania sedge in hardwood forest impacted by earthworms (www.mnstac.org)

John Bates, naturalist and author, serves on the Northwoods Land Trust Board of Directors. John educates his readers about our natural world through stories and science. In his 2018 book, “Our Living Ancestors: The History and Ecology of Old-growth Forests in Wisconsin and Where to Find Them” he shares that twenty years ago he learned from a botanist in the Nicolet National Forest how earthworms are transforming the understories of our woodlands and shorelands. This excerpt is used with his permission:

The botanist had brought along a shovel, and she dug up some soil, asking what was different about it from what we ordinarily see. Well, the soil was well mixed, relatively dark, and crumbly – in other words, pretty good stuff, and an anomaly in our usually sandy loams. There were worms in the soil, too, and they’d done that job, converting the leaves into soil, mixing and aerating the whole shebang. We then looked around, and noticed that the forest flood had virtually no spongy leaf litter such as one always expects in a hardwood forest. The leaves had been quickly converted to soil by the earthworms.

        You’d think that would be good.
        And you’d be dead wrong.

The story is yet another in the ever-growing tome of invasive species, because, after the last glacial retreat, no native earthworms lived in the Great Lakes region. We have, however, introduced at least 15 species of worms in the last century. This means that, since the glacial retreat some 10,000 years ago, our forests developed in the complete absence of earthworms. Thus, annual leaf decomposition evolved to be controlled by fungi and bacteria, which work so slowly that the accumulation of leaf litter far exceeds the rate of decomposition, resulting in the formation of a thick, spongy duff layer on the forest floor. In a rich sugar maple forest, the duff layer can be up to four inches thick, insulating the ground and keeping it cool and wet. Herbaceous plants like trillium and trout lily have adapted over thousands of years to germinate and root exclusively in this thick mat.

In the last century, however, along came the detritus-loving earthworm, and as their population grew, they rapidly consumed the duff layer in as little as a year or two, literally eating the duff out from under the seedling plants. The duff turned into a much denser layer of darker soil, and total plant cover dropped from a nearly 100 percent to less than 25 percent. Forests besieged by earthworms are often now totally dominated by Pennsylvania sedge where other native plants once flourished, species like large-flowered and nodding trillium, Solomon’s seal, blue cohosh, sweet cicely, Canada mayflower, wild ginger, red baneberry, lady fern, rattlesnake fern, bloodroot, bellwort, and many others.

In sites that were invaded by earthworms over a decade ago, the native understory herbs and tree seedlings have still failed to recover. A sharp drop has also occurred in animal species that live in the moist duff layer, like salamanders and the array of tiny insects and arthropods that ordinarily are numerous. How their decline is affecting the life up the food chain – the shrews, snakes, birds, bears, and others – is still unclear.

A study undertaken from 2007 to 2010 on 101 randomly selected northern hardwood sites in the Chequamegon-Nicolet National Forest found that 90% of the sites were impacted by earthworms. The earthworms reduced or eliminated the soil litter and thoroughly mixed the soil, resulting in major reductions in mycorrhizal fungi, soil microbes, soil-dwelling invertebrates, and a wide array of herbaceous and woody species that are ordinarily found in forest understories. Sugar maple and basswood seedlings declined and Pennsylvania sedge took over, reigning in this new environment because of its adaptive abilities to withstand drier conditions, disperse its seeds early in the season, and aggressively reproduce through spreading and the vegetative impacts were seen as profound.

Where did the earthworms come from? Mostly from anglers who toss their excess worms into the woods at the end of a fishing trip.

The only good news is that earthworms move very slowly, less than a half mile over 100 years. If we can stop introducing them, we may be able to slow the change of natural woodlands.

The bad news is that in the northern lakes district, lakes are often less than a mile apart, so the worms eventually spread from the lakeshores and meet in the woodland middle between the lakes. And, at this point, no one knows how to get rid of earthworms.

If you fish and ordinarily dump your leftover worms in the woods, cease and desist! And if you have a compost pile or garden full of worms next to the woods, please bury a metal barrier around the garden to prevent the earthworms’ dispersal. The understory of our northern forests, and all the associated wildlife, is literally at stake.


June 2021: Dragonflies: An Ode to Summer
By Trisha Moore

One recent evening, I walked out onto our shaded front deck and was surprised that there were no mosquitoes. Looking up into the sky, I saw the main reason why, a dragonfly swarm!

Courtesy of Pixabay

Dragonflies are a prime subject for wildlife watching and studying.  There is actually a name for this “dragonfly-watching,” similar to bird-watching, called “oding” (from the order that includes dragonflies and damselflies: Odonata).  They are beautiful, voracious, one of the most agile flyers on this planet; yet, can sit very still for identification, photographs and study. Sometimes, when one hovers in front of our face, it can seem that they “study” us as much as we, them. One of the most-discussed subjects surrounding these insects – in science, education and storytelling – is the dragonflies’ fascinating life cycle.

After adults mate, in flight, the female deposits hundreds of eggs underwater from her abdomen. While she is laying, the male will often be on-guard, flying nearby or will stay in contact with her body.  Water is vital to the dragonfly throughout its entire life cycle. The eggs hatch, underwater, as nymphs (some refer to this stage as larvae) and the nymphs remain submerged until they become adults. This larval stage can last up to two years and during that time, the voracious young will eat fish, other insect larvae, tadpoles and even each other!

The nymphs will go through several instars, shedding their exoskeletons each time to make room for growth. At the end of the larval stage, the dragonfly nymph will climb out of the water, dry out and its exoskeleton will break open. The insect’s abdomen unfolds (much like a telescope), the four wings emerge and after more drying time, over hours to days, the dragonfly is free to fly. Unlike mayflies, an adult dragonfly may live up to a year, although some only live for a few weeks. During that time, the dragonfly can consume thirty to hundreds of mosquitoes per day.

Take some time this summer to sit still, watch, observe and appreciate all that summer brings and especially, the wonders that are the dragonfly. Here are a few fun facts to share with your visitors, fellow observers, children and grandchildren:

  • Dragonflies are believed to be one of the first winged-creatures to evolve, over 300 million years ago.
  • Fossilized dragonflies have been found with a wingspan of up to two feet. For comparison, this is the average wingspan of a pigeon!
  • Dragonfly flight is so highly-developed and efficient that engineers study their flight to design flying robots and improve drones and helicopters. They can fly up to 35 mph (some sources say up to 18 mph), forward, backward, hover and pivot.
  • A dragonfly has nearly 360 degree vision and over 30,000 “facets” that make up their compound eyes.
  • Odonata means “toothed one” and dragonflies use their sharp mandible to tear off the wings of their prey, in flight, after catching their prey with their feet, mid-air. The prey is completely caught and consumed without ever landing!

That evening I found the relief from biting insects, I called our kids outside to ask them why they thought something had changed and we could be outside, unbitten. It didn’t take them long to notice the huge swarm of dragonflies above our heads performing their hunting stunts and acrobatics. I recalled times, in years past, as toddlers in a canoe, their fear of these large “flies.” In their young minds, the long tails could sting and the large mouths could bite (neither are truly a danger to us). On this night, as kids that have experienced and understand, they looked up to the sky with smiles and some amount of gratitude for the dragonflies arriving to rescue our evening!

Dragonfly life cycle graphic


May 2021: Ephemerals – Early Signs of Spring
By Trisha Moore

Throughout much of Wisconsin, this time of year is marked by warm, sunny days, thunderstorms, perennials popping up and early gardening. Here in northern Wisconsin, though, we have been experiencing frost watches at night and lingering snowflakes during the day.

My family celebrated this Mother’s Day with our traditional chilly hike to find the first signs of spring.

The hike provided welcomed sights of wild spring ephemerals emerging along our trail in the Nicolet National Forest.  We spotted Dutchman’s Breeches, Yellow Trout Lily, Spring Beauty (pictured right), Jack-in-the-Pulpit and Great White Trillium (pictured left).

These flowers and others are referred to as “ephemerals” due to their short appearance in our woods. The word ephemeral is derived from the Greek “ephemeros” meaning “lasting only one day.”   The native plants bloom in April – June and fade as the trees shade them out in late spring and early summer.

While ephemerals grow in a variety of forests, the most common tree species to find them under is the mature sugar maple due to its massive canopy cover, allowing for periods of direct sunlight followed by heavy shade cover. While many of these flowers appear delicate and fragile, they are hardy in their ability to grow and adapt to the cold climate and short growing season.

Most spring ephemerals accomplish growth of roots and buds below ground, in winter, using the previous year’s nutrients. They then photosynthesize during a short time period and one in which nutrient availability and water are limited by cold soil temperatures. Species like Yellow Trout Lily can take up to eightyears just to produce their first reproductive parts, the bright flowers we enjoy glimpsing in the spring!

Spring ephemerals play an important ecological role, providing early food sources for awakening insects such as honeybees, beeflies, gnats and miner bees.  Both trout lilies and spring beauties are nearly exclusive food hosts for specific miner bee species.  These insects, in turn, are early pollinators as well as important food sources for songbirds returning to the Northwoods.

Seeing the numerous spring ephemerals along our hike this year reminded me not only that spring (and summer!) is on its way; but also to enjoy each moment; they pass by all-too quickly.  Quite possibly, this year, the spring ephemerals’ best lesson to us is that if these small beauties can endure the cold, and even grow during difficult times, we can too.