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North Woods Naturalist

Sunrise west harbor  from the Sunrise Series by Stephan Hoglund

Contributor(s): 
Chel Anderson
Chel Anderson is a botanist and plant ecologist. She lives in the Hovland area and keeps close tabs on daily changes happening in the great outdoors. She shares her insights with WTIP listeners every Tuesday during North Shore Morning and North Shore Digest.  Subscribe to our North Woods Naturalist podcast.

Arts, cultural and history features on WTIP are made possible in part by funding from the Minnesota Arts and Cultural Heritage Fund. Check out other programs and features funded in part with support from the Heritage Fund.

 

 

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Bird Migration

Looking at bird migration on the North Shore

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Chel Anderson is a North Shore naturalist. She lives in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome back, Chel.

Anderson: Hello!

The spring bird migration is in full swing, and everyday there seems to be a new bunch moving in, but there is also a bunch moving out, and then another bunch comes in. So, why is this such a popular breeding ground?

Anderson: Yeah, why do we have this privilege of all of these beautiful, colored and song-filled creatures among us? What an amazing thing to be a part of. So—why? Good question. Minnesota, as it happens, is part of kind of an east-to-west-oriented swath of the North American continent that has the highest bird diversity of any region north of Mexico. So, it’s not just our imaginations. We really are right in the heart of the richest bird diversity around. That is pretty much because of the wide, amazing array of wetland and forest and open habitats. This incredible mosaic that we live in supports all these different habitats for birds. And, birds are incredibly diverse as a group in terms of the kinds of habitats that they can take advantage of. Even within what, to us, might look like the same kind of habitat, so dense conifer forest, can be occupied by many different types of birds, because they individually as a species focus on one aspect of that, even one level of the forest. So, in the case of warblers, there was a very famous study done by a researcher named MacArthur, showed that there are up to seven species of warblers that are using different levels of the canopy of a single conifer. So, in that way, they don’t interfere with each other. So, one is using just the outer tips of the branches for feeding. Another is just feeding right in close to the trunk of the tree. Some are down low in the branches closer to the understory. Others are way up high. So, this was a landmark study that showed how birds capitalize on habitat.

We have this diversity, and this is starting to make sense to me now, but also these various habitats, you know, are up against each other. And, if I’m not mistaken, edge is a big deal for birds. Can you talk a little bit about edge?

Anderson: Sure. Edge is a big deal. And how edge affects birds is really species-dependent. So, within this vast and marvelous family that we label birds, there are birds that are strictly interior forest birds. So, they are birds that really, they feed, they nest, they—even when they’re migrating, you know, when they stop and rest for the day—they want to be in, deep in the forest. And, then there are other birds that utilize resources that are more available at the margin. It might be a soft margin, so some place where instead of big, tall dense tree canopy; it’s more thick with shrubs and not much for shady tree canopy. Other birds might really like that place where there’s an abrupt change, where the forest comes right down to the water and there’s just a nice little edge of shrubs right at the shore edge. Other birds really use those edges of riparian areas strictly for feeding, but they nest in more interior conditions. And then, other birds really want to be on open ground. We don’t have a lot of birds like that, because that’s not a common feature typically on our landscape, but we do have, some people would likely be familiar with the woodcock. Well, woodcocks like more open conditions, and if they need to move around over time from one place that has an open kind of situation and then to another that is created by some kind of natural disturbance, than that works for them. The other way that edge has an impact on birds, and particularly on interior forest birds, is that where there’s edge, that tends to be a place where they can be more impacted by, for instance, non-native bird species, like cowbirds, which are actually nest parasites on other birds. They are also impacted by differences in climate at the edge of something, versus in the interior forest, and on their prey in the edge versus the interiors.

So, what I’m taking from this by inference is that if we enjoy birds and want to keep our bird populations coming in that diversity of our environment is an important thing, that we need to keep forests and open areas and marshes and all the kinds of things that we have around here. And, if we keep those in good shape, then we should have pretty good bird population during migration time.

Anderson: That’s exactly right. It’s essential. Without these things, we wouldn’t have these birds. These birds are basically coming here—the birds that don’t stay here all year—are basically coming through here or passing through here, because, in a very simple way, because there is great food resources here. And the migration, the “why” of migration, still has a lot of mystery attached to it, but it’s very certain that migration as a habit, as a behavior, predates the big glacial epochs, like of the Quaternary and the Pleistocene, and that migration as a habit developed in response to a need during a period of time when the climate was very different than it is now. One theory that birds were mostly living south, but as climate improved in the north, they moved themselves north to take advantage of improving conditions, more habitat. Another theory says that it’s just the opposite. Birds were more widespread into the north, but that with changes in climate that made the winters unsurvivable, that birds were pushed to the south. Then, as things improved, they came back to the north, because in the north we have this incredible explosion of vegetation and insects accompanied by very long days, and most birds feed during the day. So, both as individuals for survival this is a huge benefit, and as importantly, a much better shot at being successful with nesting. We never know what really was the fundamental to migration becoming a habit of so many birds, but it’s clear that that’s why they are here.

You’re absolutely right. We do have an explosion of vegetation, and particularly insects.

Anderson: Yeah!

As we get further into the summer, Chel, I know we’re going to talk about bugs. Chel Anderson, botanist and plant ecologist, thanks for helping us understand spring migration.

Anderson: You’re welcome!

Photo courtesy of tjsalo via Flickr.


 
Otter

Spring is the time to observe otters

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Chel Anderson is a North Shore naturalist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.

Anderson: Hello!

Well, otters are just plain fun. Everybody enjoys watching their antics. So, what are they doing this time of year?

Anderson: Yeah, otters, what could be a better topic for spring than otters? They are amazingly playful and curious and intelligent, as it turns out. I mean, people actually study these things. They are one of those animals that we may not think of with respect to migration. But, let’s talk a little bit about how that operates with otters.

They actually migrate?

Anderson: Well, I believe that some do on a small scale. You know, we’ve talked about how some groups of animals have major migrations and we’re all really aware of that at this time of year, but there are other kind of smaller-scale, more local migrations that happen. And, this is something that I wasn’t aware of at all until we moved to where we live now which is near the Flute Reed River, so we have this great privilege of being able to view lots of animals interacting with their habitat. Since we’ve lived there, it became very apparent that in the fall, as the winter sort of starts to set in—you maybe get some skim ice forming on the river and on the ponds along the river—that the otters disappear. Over time, watching, observing not just them or evidence of them, but also just thinking about how the habitat changes, I believe that the reason they move is that the Flute Reed in the upper portion is very apt to have parts of it that freeze right now, freeze down to the bottom, because the water gets progressively lower during the winter, the ice gets thicker and even some of the ponds, especially if the beaver dams aren’t functioning as they might have at one time, even the ponds can freeze out or become impassable kind of underwater. So, if you’re an otter who wants to make it through the winter, you have to stay some place where there’ll be a reliable food supply and a reliable place for you to move around in your favorite medium, which is water. So, the otters move out in the fall, and then this time of year, starting in usually the latter part of March, mid- to end of March, we begin to see their tracks returning, and then their tracks become very fresh and regularly moving along the river and around the ponds, but also in getting underneath the ice, you know, using whatever is available underwater, but also roaming through the woods. They’re big explorers; they really travel around kind of ceaselessly whether in the water or on the ground. But, they move around quite a bit and this winter we happened to see where an otter who was touring through the woods encountered a ski trail that was coming at the top of a hill that goes eventually down to the river. We didn’t get to observe it directly, but saw the evidence of how it just slipped right in to one of the firm ski tracks and went like a luge run right down to the river.

Somebody made the otter run for him, right?

Anderson: [Laughs] Yeah, right, I wonder what it thought about all that.

Now do these guys go downstream to the big lake, or where do they spend their winter? Do you know?

Anderson: Well, I don’t know for sure, but again, based on tracks, following tracks, especially now in the spring when they come back, then you can really follow their tracks around. And, it appears that our otters at least start out by going to the Brule, which is just a mile, as the bird flies, away or so. And, so they head out and follow various routes over to the Brule, and whether they stay on the Brule, then, which is a very large river and has very reliable water all winter and probably very reliable fish over the course of the winter. Where exactly in the river or whether some of them go down to the lake, you know, that we don’t really have any idea about, but they clearly do not stay. We definitely know that at least some of them go to the Brule, but where they go from there, I don’t know.

Now, if they are in lakes, I mean regular lakes, they’d stay in the lake?

Anderson: I presume so. At some point, young otters that spend the winter with their parents, their first winter with their parents, have to leave their parents and disperse. So, there are times when otters are moving around. They’re making some kind of migration, maybe not seasonal in the same regard as I just described, but they’re moving around, looking for where their home is going to be that won’t be in competition with something else. You know, otters really have made a great comeback in other parts of Minnesota where they disappeared from in the early 21st century. In southern Minnesota the otters pretty much disappeared, because of habitat destruction and water quality degradation. They’re making a comeback in that part of Minnesota, but we are really blessed with the habitat that supports a very vibrant population of otters, because we have excellent water quality for the most part, we have a surrounding landscape within our watersheds that support that. And otters eat a lot of fish, but they also eat other things, clams, etc.

You know, a number of years ago we were canoeing on Lake Kabetogama and we heard this mulling and hissing and we were fairly close to shore, and then, all of the sudden, two or three of these guys popped up and spit at us and then went back down again and then popped up and hissed. So, we figured right away that we must have come in to a family of otters, and the young ones were still young enough that the parents were concerned about us.

Anderson: Yeah, that’s very, very likely, because they’re going to stick together and learning the ropes, those young otters, and having the chance to play around with each other. Which, like in all mammals, including us, play is a way that we develop as our physical selves as well as our social selves. And, so that’s a big part of what they’ll be doing and they do that with their siblings and with their parents. Otter families might consist of typically more like two to three to four but as many as six young otters in a family, so it’s a lot to take care for the adults, you know, to manage all these youngsters and to keep them busy learning what they need to learn and getting them to places where they can work on their skills at catching their prey. So, parents will catch something and bring it close and let it go and they repeatedly do that to give them a better shot at catching something and get their techniques down. So, there’s a lot of training that will go on over the course of the summer and hopefully they’ll be successful.

Chel Anderson, botanist and plant ecologist. Thanks for helping us understand otters!

Anderson: You’re very welcome!

Airdate: April 27, 2011

Photo courtesy of orkomedix via Flickr.


 
Quaking Aspen Bud

Learn to keep track of what’s going on outside

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Chel Anderson is a North Shore naturalist. She lives here in Cook County. She joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome back, Chel.

Anderson: Hi!

Well, all these many weeks we’ve been talking about phenology. Now, let’s talk about how other people besides you and me can record their observations, and how do we do that?

Anderson: Yeah, well, I think it is a good thing to spend a little time talking about, even though it’s maybe a little drier subject than some of the great natural events we get to talk about, but as we always say, phenology is a study, it’s a science, and it’s really about paying close attention to the lives of plants and animals and natural phenomena of all kinds. And, to be useful as a study, one really needs to record those observations. We can all enjoy making them, and I’m not going to diminish the importance of that at all, because I’m an inveterate observer and I don’t want to feel an obligation to do something that I enjoy. But, I have found in my own life as an observer that recording, making a habit of recording, really has helped me focus my attention and has helped me discover things on my own, not that they’re new to science or anything, but just new to me, that I wouldn’t have noticed otherwise, because I wouldn’t have been watching closely enough. So, in terms of a way to kind of experiment with this, if it’s something you think you might want to try, is to pick out something that you can easily go and look at everyday. Pick a tree, pick a shrub, pick a plant that’s going to emerge here as the spring comes on, and make a habit and visit that. Plants are good, because, again, they’re stationary. I’m not saying animals aren’t worthy of our attention, they are, but they’re much harder to track easily. But, you can certainly choose an animal if you wanted to. I’ll just use a plant as an example. So, pick a tree or a plant of some kind, and go out at this time of year and figure out where are the leaf buds, where are the flower buds, and take a close look at the bark. What does it look like now? Make as many kind of careful observations about that particular thing as you can right now. Then everyday, or as many days as you can fit into your schedule, go out there and look at those same parts of that plant and start to notice differences, because you will, eventually, begin to see differences. And, at some point, you’ll start to see big differences, even just from one day to the next.

We’re talking about mental time-lapse photography.

Anderson: Exactly. That’s great. Yeah, that’s a great analogy. And, if you want to go so far as to do it, take a little notebook with you, and when you are out there make notes about what you saw.

Well, if you make notes and file them in some way, then the next year and the year after and the year after that, you can make those comparisons and you can see how things have either stayed the same or changed. I know people do this with gardens, for example. It’s kind of the same process.

Anderson: Exactly. Yes, and you can begin to see for your particular species of thing that you’re observing or groups of things, and for your particular location, what is the range of time that the buds start to plump up on an aspen tree in your yard. And, is that the same when they do it on an aspen tree that’s just 50 yards away in a different part of the woods by where you live, because not all species are acting totally in synchrony on a day-to-day basis. They have a range that they might operate in. So, you can start to notice changes like that. So, recording helps us, again, focus a little bit more. You can record just in a notebook by hand. You can go so far as to take your written notes and observations and put them into a database, if you’re good with databases and that can help you sort and compare your information from year to year eventually. You can also decide that you want to check out the opportunities that are there for people like those of us who make these kinds of observations and enjoy doing it to contribute to big databases that are looking at changes and patterns and trends across large areas and across time. As you said, not just from year to year, but over large lengths of time. Phenology is not a new thing. Human beings have been using phenology in the sense of observing the world they live in since they came to be, because it’s how we survive. So, observing and taking note of when things happen is a part of our nature, and cultures have actually been recording phenological observations for millennia. Two great examples are the Chinese Cherry Blossom Festival and the Chinese Peach Blossom Festival. They have records going back over 1,000 years. So, you can really look at some spectacular trends in recording like that.

Well, I suppose that the early humans when they began to realize that certain things happened in certain cycles, particularly those who lived in areas where there was climate change from spring, summer, winter and fall, that it was to their advantage to know when those things would happen, so they could be prepared for it. So, yeah, it makes sense that they must have recorded it in someway or another.

Anderson: Oh, absolutely. It isn’t hard at all, I don’t think, to believe or know, just feel it in your bones, just like we feel spring, you know, it’s not just something on the calendar. I don’t know about you, but I can feel spring coming.

Yeah. It’s in my joints usually.

Anderson: Or winter coming. You know, these are some things that we, too, as a species have been a part of for our entire existence. Even though we’re much more at arms length from a lot of them now, that doesn’t mean that they aren’t still a big part of who we are and they definitely are a big part of where we live.

Chel Anderson is a botanist and plant ecologist. Thanks, Chel, for helping us understand how to keep track of what’s going on around us.

Anderson: You’re welcome!

Photo courtesy of Matt Lavin via Flickr.


 
Traditional Maple Sugar Tap

It’s maple sugar time on the North Shore

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Chel Anderson is a North Shore naturalist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome back, Chel.

Anderson: Hi!

Well, it’s already starting. Cold nights, warm days; that means the sugar maple sap is flowing.

Anderson: It does, and we can all look forward to the products to come. We have a lot of maple syrup producers here for our relatively small population, and so we have a lot of experts for you all to call upon to really talk about the whole maple syrup production end of things, so maybe we’ll talk about the mechanics of sap flow, because sap flow as happens in maples is not really very common. There are very few species that actually have the kind of sap flow that maples, sugar maples, red maples, have, and it maybe be something that people don’t have a lot of understanding.

So, I understand that birch does?

Anderson: Yeah, birch are another species that do up here, but they’re really the only two groups of species that really have this kind of sap flow.

Why is that?

Anderson: Well, why? That’s always a really big question that I’m not sure any of us can really answer. It’s to do with their evolution as species that has made them different from other tree species, but the mechanics that they have evolved to have that create a sap flow are quite interesting. First of all, a misconception to clear up to start with is that we all learned in grade school and biology that sap wood in the tree conducts the water from the roots up to the rest of the tree and that the nutrients, the carbohydrates and other nutrients that the photosynthesis creates is conducted by another set of tissue called the phloem into the tree, back to the roots and into other parts of the tree. Well, in the case of the maple, that isn’t exclusively true, and that’s why the sap of the maple is sweet, because at this time of year, it’s actually absorbing sugars that were created by the photosynthesis during the growing season and stored in the tree in the form of sugars, sucrose, and that’s being absorbed into the sap and being carried by the xylem, by the sap wood. So, it’s a little different from what is happening in most trees. So, like other trees, things flow in both directions, up and down, but in the case of trees that actually have a sap flow, like maples, something forms called positive pressure, suction and osmotic pressure. Those three things are the mechanical aspects of why sap flows out of your tap in a tree or out of a wound. Let’s say, a big branch has broken off of a tree in a winter storm or something, or a beaver cut a birch tree down in the fall and now in the spring all this sap is falling out.

I’ve seen red squirrels nibble on branch ends of maple trees and lick the sap.

Anderson: Exactly. Red squirrels: really smart.

They are going to take over the world. Red squirrels and cockroaches.

Anderson: Yes, and they’re so energetic besides.

Let me ask you. When you talk about sugars and storage of sugars, now, do those sugars help the tree do something besides just produce sap?

Anderson: Oh sure. They’re part of the nutrients that the tree, that the photosynthesis--

They’re using it?

Anderson: They are using it, but in the fall, as things slow down, the tree can’t use all of the nutrients, carbohydrates that are being created, so they end up being stored in the cells in the tree and the tree freezes up and nothing is happening, until we start getting the weather cycle that you just described, warm days and cold nights. And, with the warm days, when the tree warms up and the cells in the tree warm up, there is carbon dioxide within the cells of the sap wood that gets released out into the spaces between the cells. And there’s also carbon dioxide in the sap itself and as it thaws and becomes liquid some of that escapes into those intercellular spaces and that creates pressure inside the tree.

You talk to a lot of tree tappers, and there are good years and not-so-good years. Sometimes that might be related to the weather, but is it also related to what happens to the tree, like, in the fall? Are there things that can affect the amount of sugars stored quite apart from the weather?

Anderson: What makes for good years and bad years is probably primarily due to these weather patterns and the access of trees to a good source of moisture to replace the sap that flows during the course of a warm day. So, once the pressure builds up, then sap will flow out of your tap in the tree. As the cold night comes, if the night gets cold, then the carbon dioxide actually shrinks and contracts, because it’s cool, so it contracts in between the cells of the tree, and some of it is reabsorbed into the now-freezing sap and cooling sap. And, when that happens, that creates a suction that draws water from the roots up into the tree to fill—so it’s a suction effect that happens. Then, when it warms up the next day, then the sap will flow again. Well, if you didn’t have a good source of moisture, of water, to move up from the roots, maybe a year when we don’t have a really good snow cover, and so the roots are down in frozen ground for the most part, there isn’t as much access to ground water. Those would be years when having a really strong flow would be much more difficult to create on a daily basis, because there wouldn’t be that access to a good resupply of the water. And then, of course, if it doesn’t get cold at night, then you don’t get that suction created and sap can continue to flow during the night, but then, of course, there’s less and less pressure, because you aren’t replenishing in the way that suction replenishes the fluid aspect of the sap.

Good plan.

Anderson: Yeah, and we don’t have to do anything!

Chel Anderson, botanist and plant ecologist. Thanks for helping us understand maple sugar.

Anderson: You’re welcome.

Photo courtesy of Sébastien B. via Flickr.


 
Snowshoe Hare

Elusive snowshoe hares – lots of tracks, few sightings

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Chel Anderson is a North Shore naturalist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel!

Anderson: Hi!

Well, one of the most common tracks we see in winter snow is the familiar snowshoe hare. So, what are they doing to get ready for spring?

Anderson: They are doing what everything’s doing still, right now, which is just trying to stay alive and that’s increasingly hard at this time of year if you’re a browser in particular. So, something that’s eating the woody vegetation in the case of wintertime. Lots of things are getting buried under the snow that otherwise would be available to you, and you’re eating right along and snowshoe hares don’t travel huge distances in the winter. They’re not, you know, covering huge areas, so they’re working through their available foods, which, at this time of year, like I said, includes, you know, woody vegetation, but not heavy woody vegetation. They can’t be, you know, eating great, big limbs of things, they have to work on small twigs, on buds, on the inner bark of branches of trees that might fall down, you know, in a windstorm or something, or in the case of willows, things like that, that don’t get real heavy branches or stems, they can clip those off and work on the inner bark of those. And, of course, they’ll also eat the needles of conifers, so they’re just trying to stay on top of making sure they get enough to eat and out of sight of predators, which also are on the steady lookout for prey and hares are a very important prey species for many critters: foxes, coyotes, fishers, bobcats, lynx, raptors, owls, goshawks and returning things, things that will be starting to come back early on as winter kind of starts to melt away, new things will be on the lookout for hares. So, hares spend a lot of time this time of year, and really at all times, just kind of resting during the day when they can stay of sight, find a secluded spot and hanging out there. And they’re primarily crepuscular and nocturnal, so they’re feeding mostly at night, and they generally stick to fairly regular routes and areas that they spend different parts of their day in.

My yard.

Anderson: Yeah, and that reminds me that I just feel like the dullest of observers this year, because they have been lots of tracks around where I frequent, you know, trails around our house, and I have yet to actually see a hare this year. And, I just can’t believe how dull-witted I must be to not have been able to pick one out this year.

I don’t know. Earlier in the year, I did see quite a few, but this winter I haven’t really seen that many. I’ve seen tracks, but I haven’t seen them actually.

Anderson: Well, as I said, they are mostly active in the dim light and darkness, so I guess that gives me a little bit of an excuse. But, one thing is that they’re probably aren’t as many around as it seems based on the tracks, because, again, hares are sticking into a fairly small area and they’re very well camouflaged. They do take quite awhile to fully molt and change color, so that’s why sometimes in the spring when the snow goes early we see hares that are looking really obvious because they’re still mostly white and the reverse in the fall. So, it takes about 10 weeks, I think, for the total molt to happen.

I tend to categorize hares, bunnies, and rabbits all together and I shouldn’t do that. These are snowshoe hares.

Anderson: It’s a common thing. These are snowshoe hares, so perfectly, marvelously adapted to our world here, because they have those incredibly long hind legs and huge feet that allow them to literally float on top of the snow. So, I don’t know if you stepped off the trails anywhere when the snow was at its deepest, but around our place it was about 40 inches deep. So, you know, without your own snowshoes of some kind of another, it was not much for good going out there. But, again, when the hare populations are large, they tend to show up, you know, a lot in the summer out eating in the herbaceous vegetation that grows along the roadsides, especially at night, again, because that’s when they’re most active. And, during the time when the first litters are being born, then, you know, there’s a sudden surge in the population.

When is that going to start?

Anderson: Yeah, well, they’ll start in the spring. Here, hares might have two litters over the course of the summer. They’re very prolific breeders. Hares tend to live only about a year, so they have to do a good job on the reproducing side in order to keep their numbers going. And they do have cyclic populations, the reasons for which are not all that well understood, but it’s kind of a 10-year cycle of peaks and valleys, and the predators that they feed have kind of a trailing cycle often that’s associated with the cycle that the hares have.

When you say they’ll start to have litters in spring is it in April? May?

Anderson: Oh, May. June. Yeah. And, I’m not sure where the cycle is supposedly right now. I’m pretty sure it’s not at peak right now, but I don’t know if it’s really down in the valley or if it’s somewhere in the middle. But, there may just be fewer around then there were, say, a few years ago. I’m not really sure, but it’s discouraging to me that I haven’t actually seen one, but I’m going to keep an eye out for them.

Chel Anderson, botanist and plant ecologist. Thanks for helping us understand snowshoe hares.

Anderson: You bet.


 
Saw-Whet Owl

The Saw Whet Is Our Smallest Owl

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The smallest owl in our north woods is the saw whet. Even though it’s only eight inches tall, it’s quite common and often seen and heard in our conifer forests. WTIPs Jay Andersen spoke to local naturalist Chel Anderson about this attractive little owl.

Photo courtesy of Blake Matheson via Flickr.


 
Red Fox

The Sometimes Secretive, Sometimes Obvious Red Fox

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Chel Anderson is a botanist and plant ecologist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.

Anderson: Hello!

Well, lots of tracks in the snow, and I’ve noticed by the size some must be fox. What kind of foxes do we have here?

Anderson: Foxes. Yeah. Very cool animal. Very common around our area, and pretty much across the state; one of the most successful predators on earth. Very adaptable to many different habitats, which is kind of a common theme. You know, if something’s really common over a large area, then it’s usually because it’s been able to adapt to lots of different kinds of habitats, from woods and forests like we have here to urban areas. So, yeah, fox are very common in Minnesota, in this part of Minnesota.

But, you don’t see them that often, do you? Or is it just me?

Anderson: Actually, I think I see them pretty often. But, I think it’s just a matter of luck, you know, in terms of whether you happen to be traveling regularly in an area where a fox is spending a lot of time and having some success with, you know, searching for prey or near their den or they take up residence near you and you get to see them. I’m sure it’s more or less serendipity. It’s certainly not because I’m out there following them around, but, seeing a lot of evidence of them, of course, in the winter with the tracks, like you mentioned. Here, in this part of Minnesota, the fox that we have is the red fox. The other fox that occurs in Minnesota is the grey fox. We do not have them here, although the red fox has a variety of color phases, which mean that we may see fox which are not the pure, beautiful, rusty red that we think of with black ears and nose and legs and a white tip on its tail. We might see the silver fox, which is more grey and black. There is also a color phase of the red fox that might be all black. Or the cross fox is another color phase which is red with dark bands across the back and the shoulders.

When you talk about phase, I often think of phase as a phase that the animal goes through. Is that true or is this a permanent state?

Anderson: No, it’s a permanent state. Color phase means just that within the genetic variability of the colors of the species, you can get these mixes. Just like in our wolf population. Not all wolves are exactly the same color. But, in the fox they’ve really defined these as color phases. The red fox that we have here stands about 15 inches or so at the shoulder. They’re about three feet long, including that just gorgeous fluffy red tail with a white tip, which is about 13 inches long or so, so a considerable amount of its length is that beautiful tail that’s flying out behind it when you see it scampering across the snow or across the road. You know, they weigh plus or minus 10 pounds. They are primarily hunting and moving around at night. They have fantastic night vision. In part, that’s because in addition to the light-sensitive cells of their eyes, behind that layer, they have another layer of cells that reflects light back through their eyes and really enhances their ability to spot their prey. They also have incredibly keen hearing. They can hear the rodents in the subnivian or rustling in the leaves in the summertime. In the summertime, they can actually apparently hear worms moving on the surface of the ground. Even though their classified as carnivores, they’re very omnivorous in their habits. So, you know, they eat rodents and catch a lot of prey, but they also eat berries and nuts and invertebrates. They’re not real fussy about what they eat.

OK, so they seem to be pretty good with everything, how about smell?

Anderson: Excellent sense of smell.

Might have known.

Anderson: Might of known. How else can you be a successful predator if you don’t have a good sense of smell? They also are very fast. They, for short distances, can run up to 30 miles an hour.

What are they after? Like, snowshoe hare?

Anderson: Sure, they’ll go after hares, red squirrels; they’ll dig down through the snow to get at things that are under the snow. When the snow isn’t, well, even now, when the snow is pretty deep, if you had a chance to watch them closely, you might see them listening closely and then pouncing down through the snow with all their legs come together and pounce down deep into the snow. They can leap up to 15 feet. So, if they hear something, you know, listen carefully and then determine within very close distances just how far that is away, they will leap to it and plow down through the snow and then dig furiously to get at it. This is the time of year when fox are breeding and mating, so in addition to being more visible because we can look for their tracks and maybe even see them out touring around, we might also have the best chance of hearing them. They make many different kinds of vocalizations and use them during the course of the year, but they’re most vocal during this breeding/mating time of year. The most common call is described best by I’m not sure what word, but some people like to say it’s a bark. It doesn’t really sound like a bark to me. Some people call it a scream. It seems more like some combination of that to me; it’s a barky scream.

Go for it, Chel. You’ve done this here before. You’ve given us an impression of animals before.

Anderson: Oh, I don’t think I could do it. It’s too weird. It’s too strange and I haven’t had a chance to just, you know, listen and soak it in enough to really feel like I could make it. To my ear, it also sometimes sounds like it ends almost with a short, little howl. So, it’s a “roooowwwrr.” Especially at night in February, March, these are the good times if you’re out, you know, we have some nice, mild nights this time of year, great time to go out and listen for all kinds of interesting sounds of the night.

Let’s set this record straight, now. Male fox, female fox. Give me the right names.

Anderson: OK, well, female fox are called vixens, and my understanding is that male fox are called dogs.

If the male and females are mating in February-March, when do we expect to have little foxes?

Anderson: Well, the gestation period for foxes is just over 50 days, I believe. So, you know, it could be anywhere from April sometime into May. They’d be born down in the den and be in the den for awhile before they’d be able to come up to the surface so to speak and move around. Then, you know, they hang out and play around the mouth of the den.

Like any canine.

Anderson: Like any canine.

Chel Anderson, botanist and plant ecologist. Thanks for helping us understand foxes.

Anderson: You’re welcome.


Photo courtesy of Ray Chang via Wikimedia.


 
Ice on Lake Superior

Activity under our frozen lakes

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Chel Anderson is a botanist and plant ecologist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.

Anderson: Hi!

Well, a couple of weeks ago, some volunteers jumped into Lake Superior to help raise money for a charity. Yes, they did. They got out right away, leaving unanswered the question of what’s going on in the dark below the ice in our frozen lakes. So, tell me, what’s going on under the ice?

Anderson: It is cold in the water these days. Not as cold as the air temperature, though, right? At least most of the days recently. It’s not only cold, cool to cold, down there, but it’s also very dark, because, right, all the light from the sun, for the most part, is bouncing back into the sky and so, it’s pretty darn dark down there. But, it’s not all quiet down there. Things are still moving around. When fetching water from the water hole at our place, it’s not at all uncommon for us to see diving beetles moving around, giant water bugs have been at the water hole, dragonfly nymphs are being their whiz-bang predators that they are; all that is going on. Water scorpions have shown up at the water hole. So, lots of, you know, life is happening. It’s happening at a slower pace, but things are going on. Not just aquatic insect life, but also small mammals, like water shrews and star-nosed moles. They spend a lot of time, this is where they do most of their feeding, is in the water. One of the key things that’s going on, though, right now under water is that because the lakes are sealed tight with ice, the oxygen that the lakes went under the ice with is slowly being consumed by all the things that live there, except the plants, which normally take in carbon dioxide and give off oxygen, adding to the oxygen, but they’re not doing that, because there’s no light. So, the lakes have this kind of total budget of oxygen that’s there and until the ice leaves, that’s what everything has to live on. So, it’s being consumed, it’s not being created, so that, over the span of the winter, begins to have an effect on the life there. One of the really interesting ways to actually see the impact of oxygen changing over the course of the winter is to look at a little zooplankton that are called Daphnia—that’s the genus that they’re a part of—and they are planktonic crustaceans. They’re also called water fleas, but I’m not going to call them that, because they’re not fleas.

There have been some reports in the news lately about Daphnia as having a genome.

Anderson: Yeah, bigger than anything. Yeah, right.

Bigger than anything, and they’re hardly big enough to see.

Anderson: Yeah, right. Exactly. Yeah, good, I’m glad you brought that up. It’s very fascinating that this tiny little thing—so think, when I’m talking tiny, I’m talking the size of an apostrophe on your keyboard. So, these are tiny, but they are visible. You can actually see them.

And we have them here.

Anderson: And we have them. They’re ubiquitous in all freshwater ecosystems. They have tree-like tentacle arms that they flail over the tops of their heads which sends them spinning in kind of backwards circle, which seems kind of silly, except for it also drives water through their outer shells. Then, the filter algae, which is what they eat, and oxygen out of the water that passes through them. So, that’s why they do all this flailing. But, they have this amazing ability that is probably part of this huge genome that they have that’s given them the capacity to adapt to the really dramatically-shifting conditions that occur in their aquatic habitats, which can range from lots of water at one time of the year to no water sometime else, but also to changes in oxygen levels. The adaptation that they have that relates to oxygen is that they can make hemoglobin. So, during the summer when there’s lots of oxygen, they are translucent. But, during the winter or any other time when oxygen begins to be depleted, they begin to make hemoglobin for themselves so that they can survive in the depleted oxygen condition.

What does the hemoglobin do?

Anderson: Hemoglobin is the best way to move oxygen from a source of oxygen to where it’s needed that any life form can make. So, it’s the thing that makes our blood red, it’s the thing that moves oxygen from our lungs to the rest of our body, to our organs, to our muscles in our bloodstream. So, they are making this for the same purpose, because, in the summer when there’s lots of oxygen, it’s just moving right through them, there’s plenty of it. They don’t need any special mechanism to bring oxygen from water into their systems to use. Once the oxygen starts to get depleted in the water, then they need hemoglobin to do that transfer more effectively and efficiently. So, because they’re making hemoglobin, as the winter goes on and the dissolved oxygen in the water becomes diminished, they begin turn color, because the hemoglobin they make is red, too. So, as the oxygen becomes lower, they get pink, and when it gets really low, then they are red. And, how long the ice lasts has a big impact on how quickly that oxygen begins to be replenished. If the ice lasts way, way late into the spring, well, of course the oxygen then gets even lower in the lakes and ponds than it does if the ice goes off early.

Before we end the discussion, I know we agreed we’re not going to talk about fish, because we talk in all other sets of circumstances, but do fish slow down in the winter?

Anderson: Yes, fish slow down. I read some great descriptions of the people diving under the ice and actually approaching groups of sunfish that are just totally still, barely moving in the water. They were described as like autumn leaves suspended in the water, and as the person went by them or dove through them, they could just move their hand to part them like you’d part leaves on the ground, and they’d just kind of shift over, not moving on their own, but just moving because the diver was moving the water to push them aside. But, yeah, they’re just conserving, conserving, conserving so that they’re just sipping, sipping oxygen so that they can make it through.

That explains my luck ice fishing. Chel Anderson, botanist and plant ecologist, thanks for helping us understand what’s going on under the ice.

Anderson: You’re welcome.

Photo courtesy of Brynn via wikimedia.


 
Tree Well

Under And Around The Snowpack In February

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Chel Anderson is a botanist and plant ecologist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.

Anderson: Hi!

Well, even though it seems calm and serene in the winter woods, I know there’s stuff happening. So, let’s run down the list of who’s doing what now in the woods.

Anderson: Ok, yeah. Things that kind of give us—both seen and unseen—that give us a sense of where we are in terms of the winter season. So, one thing that tells us that we’re into the January-February sort of period is that the birch trees, the alder shrubs, the spruce and the balsam trees, their seeds are coming down out of their little cones and fruits. And this is a perfect time of year to try to learn about the shapes and start to identify those seeds, because they’re really visible on the surface of the snow in between snow storms and they’re not all coming down at once. So, the visible numbers are being replenished regularly in between the snowfalls. So, that’s one thing that’s going on and those are being noticed and enjoyed by many of our local birds, including, for me, the first group of redpolls that I’ve seen. Also, I personally had a recent observation of snow buntings still around. And I know they appeared on the Christmas bird count, but there are apparently some still around. Of course, they’re birds of the arctic the rest of the year and they’re going to spend time in the winter wherever they can find some open areas or places with seed sources available on the ground, specifically. I’ve never heard of anyone seeing one at a bird feeder, but that doesn’t mean it couldn’t happen I guess. I also heard a report of a cardinal. This was local to town area, so if you’re in town, keep your eyes open. Maybe you’ll see it, too. Also, it’s worth mentioning that all over the North Country now the bear cubs have been born. They typically come in at about 12 ounces. So, now they’re eating madly and sleeping a lot and, courtesy of their mothers, they’re bulking up, heading for that hoped for 10 pounds by April. So, you know, we wish them well.

I’ve seen a number of shrews lately, I haven’t seen them earlier in the year, but I found that kind of interesting because of the amount of snow, but I’ve seen them on top of the snow, I’ve seen burrow trails, as we’ve talked about. So, are the mammals starting to think about having babies now, too?

Anderson: Well, I wouldn’t think so, yet, but they’re probably doing whatever they need to do in terms of coming out of the subnivian in order to keep eating. All these small rodents, it’s all about keep eating, because they’re not spending any time dormant. They’ve just got to keep eating to keep alive, you know, furnaces running. So, if they’re having trouble finding enough to eat down in the subnivian, then they’re going to come out and go somewhere else. And in terms of other indications of the season, tree wells are also something that, pick out a few different trees that get sunlight, direct sunlight, during the day around the trunks where they meet the snow and start watching the tree wells really start to form now more significantly at this time of year. Because, the difference in what heat the tree trunks absorb versus the snow absorbs means that it’s quite a bit warmer at those tree trunks and so they start to create that little depression around the base of the tree.

Now, is that because our days are getting noticeably longer? Is the sun out more? Is that what causes the tree well?

Anderson: That’s partly it, but even more so it’s the angle of the sun. So, the angle of the sun is getting higher, so there’s really more energy reaching here, even though it might not seem like that everyday, but that’s what’s going on. Trees that have a darker-colored bowl for one reason or another, of course, their wells are going to be created faster than those that have a really pale color, because they’re absorbing more heat.

Yeah, they’re absorbing the heat, and then along with that additional angle, I can see what you’re talking about.

Anderson: Speaking of depressions in the snow, this is also a great time to be checking out possible locations where grouse have sheltered in the snow over night. And, as many of our listeners may already know, grouse use the snow as a place to both get some insulation from the cold overnight, but also to be out of sight of predators. They have this amazing routine of diving, literally diving, into the snow and I have to think that earlier on this winter that crust that we had that was, you know, a half-inch or more thick must have been a little bit of, I don’t know, a disincentive. I don’t know how they handled that, because I did see some, definitely saw some earlier in the winter, but, boy, it would seem like it would be kind of dangerous to be plowing in. But, now we have enough light snow on top of that that there’s room there. And so, they dive in, literally dive into the snow, and then they kind of push and tunnel forward from where they end up and they push the snow out behind them, to close the door, so to speak, on their little shelter. Then they kind of fluff out and push the snow around to make it a little bit more of a cave and that’s where they spend the night. When they’re ready to leave, then they just push themselves up and out or sometimes they burst out, sometimes from underneath your snowshoe. I don’t know if you’ve ever had that experience.

One time.

Anderson: Oh, great. Yeah, well, it’s definitely a heart-attack moment.

Well, he wasn’t that close, but he did take off and I figured “What is that?!”

Chel Anderson, botanist and plant ecologist. Thanks for helping us understand the seen and unseen in the winter woods.

Anderson: Always fun.

Photo courtesy of aka_lusi via Flickr


 
Superior Ice (by Roger Linehan)

The Big Freeze on Lake Superior: Where and When

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Chel Anderson is a botanist and plant ecologist. She lives here in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome back, Chel.

Anderson: Hi!

Well, this is the time of year when we start to speculate about how much ice there will be on Lake Superior. So, let’s talk about this and the impact that big lake ice has.

Anderson: With pleasure. I don’t know why, but ice on Lake Superior is incredibly exciting to me. So, I hope this isn’t overboard for those who aren’t that excited about winter in general, but I’ve lived here quite awhile now. I came up here in 1974 and, you know, during that time, we pretty much always have some ice on the shore by this time of the winter, but it’s really a fairly uncommon phenomenon on the lake, since I’ve been here, anyway, to have actual ice out on the open lake that makes it look like it’s iced over or, really rare, to have the lake actually freeze over. As we’ve talked about on a number of occasions, Lake Superior is a big heat sink. It absorbs warmth all during the spring, summer and fall and it does warm up, even though it’s not what we would call super swimmable most of the time. Because it’s such a huge mass of water, even if it’s only getting up to 40 degrees or 50 degrees in places, it takes a very long time for that heat to dissipate and get the water down to the point where it’s cold enough to freeze. So, this is a long process. So, it happens, ice forms out on the open lake and even in protected areas of Lake Superior much later than it does on our inland lakes. As we’ve talked also before, water out on Lake Superior, as everywhere else, as it cools down, when it gets to that 39 degree temperature, the water sinks into warmer water below, it’s replaced by warmer water, so that process has to go on and on and on until everything has cooled down to 39 degrees and the water is no longer sinking and being replaced by warmer water. And at that point, then the water at the surface can begin to go lower and actually get close to freezing and as that happens, and it can happen at different places and different times, because Lake Superior has shallow, more protected bays and those are going to be the first places that ice on the open lake is going to form. So, examples of that besides our harbor would be down by Duluth, up at Grand Portage bay, Thunder Bay. Those are places where you have big, shallow bays that are going to be some of the first places where ice will form on the open part of the lake. Then, elsewhere, once the surface water is actually staying colder than 39 degrees, wind becomes a huge factor in whether an ice sheet actually forms. So, the water can be down at 32 or even lower, but if we’ve got wind going on and it’s jostling it and moving it and creating waves and turbulence, just like a river, it’s not going to freeze into a sheet.

The lake is big, but it’s not affected, it does not have tides, but what is that phenomenon and does that keep the lake from freezing?

Anderson: Lake Superior does have a seiche and that can be affected by differences in barometric pressure over the different parts of the lake and it’s just a movement of water and certainly if there’s ice trying to be formed but you have any kind of an undulation, if it’s enough of an undulation, it’s going to prevent creating a sheet.

Well, I’ve been up here a couple of decades and in that period of time I’ve noticed there have been some flyovers of the lake. But, I can only remember a couple of times that it was reported that the lake was actually frozen over. What does it take to do that and does it freeze thick?

Anderson: Yes, it’s been very rare for the lake to completely freeze over, and, of course, we know it not by our own empirical experience, we can’t get up on a ridge and tell, but there’s satellite imagery that’s been available for decades now and you can actually go on the web and look at NOA’s Great Lakes Ice Atlas and you can actually look at charts of winters from the 1970s up until 2003 where they’ve taken those images and they’ve then made a chart that shows the great lakes and shows the maximum ice cover for a given year. So, the ice is going to be variable in thickness, even in a year like that. But, it’s going to have a lot of areas with very thick ice, because in order to be durable out on the open lake, ice has to be thick. Once an ice sheet forms out from our shore here, whether it survives very long or not is really dependent on the weather right then. Our ice usually forms on a cold, still night. Even if we don’t get those sheets of ice that last very long, even just having the ice form and then be moved around by the waves creates all this interesting dimension to the shoreline that we don’t see at other times of the year.

There’s a phenomenon that I’ve noticed that doesn’t seem to be too related to waves, but just in the general motion of the lake, when ice that’s, you know, less than an inch or maybe an inch, at the most, thick, starts to move into shore and slide up over itself and creates an incredible sounds and it’s an amazing experience.

Anderson: I agree totally. It’s just an incredibly inspiring and intriguing phenomenon. Both the sounds, as you say, if it’s really thin ice and it’s just starting to break up, it has this really light—what’s the name of that instrument that has the—the glockenspiel! It has that tone, just this beautiful light, clear tone, of small, bright sounds that come out of the ice. But, if it’s a thick sheet of ice that’s either formed on our shore or formed somewhere else and blown over here, but if one forms here or elsewhere and it comes to our shore when it can be pushed along by the wind and actually grind its way, both either right up, like you’re talking about, on to the shore or along the shore, but they’re grinding away on the bedrock as they go, and that’s a really good example of how lake ice plays a huge role as a disturbance factor on our bedrock shores.

Is there any difference in the character or quality of the ice on this side of Lake Superior as opposed to the other side?

Anderson: Big sheets of ice form more frequently and earlier in the year in other parts of the lake where the character of the lake is generally shallower. That’s why often the first ice sheets we see come from someplace else on the lake, could be the south shore, might be the east side of the lake, where there are big areas that are shallower and they can be very thick when they get here and they come ramming up on the shore.

Chel Anderson, botanist and plant ecologist. Thanks again for helping us understand this time what’s going on with ice on the big lake.

Anderson: Always a pleasure.