Thursday, February 28, 2013

Fallible wild animals

More photos by Zac. Penny included for scale
What: On our tracking adventure at Bread and Butter Farm, we were also impressed at the density of coyote sign - they must be snacking on all them li'l rabs. We decided to trail one of the paths for a ways. Pretty quickly, we started noticing blood spots in quite a few places along the trail. Female coyotes are monoestrous (having only one period of "heat" per year). It's relatively short, about 3-5 days and happens sometime between late January and early March, so we got lucky in our timing. The females will scent mark with their urine (which has blood in it). It shows up as small reddish yellow drops on the snow. The female we followed seemed to be on a hunting foray, traveling in mostly straight lines with occasional detours to investigate something that caught her attention (for as long as we followed her, she was unsuccessful in her hunt).

Zac and I both wound up post-holing while trailing her along a small brook that was frozen over. I tend to take clumsiness in humans as a given, but never expect it from wild animals. It's always jarring to see a squirrel miss a branch it's jumping to and fall to the ground, or watch a beaver trip as it's stepping over a rock, or catch a cottontail running into a fence. In this case, not more than 30 yards from where both Zac and I broke through the ice, we saw the tracks in the image above.

It appears like the coyote postholed, then slipped with her right front foot. The track just below the dark circle (the posthole) is her rear foot swinging out wide to steady herself. That 3' provided us with a hundred little stories and questions that we only began to answer as we made our way along the trail over the next half mile or so. It's always refreshing to remember that every now and again wild animal show their fallibility.

Ecological notes: In Centennial Woods there's an abundance of fox (red and gray) and deer, but no coyotes and only a very few rabbits. It made me wonder if there was a correlation between the presence/absence of those species. I found some interesting studies that look into the relationships between these species (as well as bobcats and even Lyme disease). Here's a summary of what I found:
  • Coyotes eat gray foxes (not sure I believe this, or at least that this has a significant impact on gray fox populations)
  • There's an inverse correlation between fox and rabbit populations. Where cottontails are in great abundance, red foxes, an obligate generalist, will shift and specialize in hunting them (study)
  • Bobcats prefer rabbits and rodents and will eat deer second (study)
  • There's an inverse relationship between fox and coyote populations (coyotes apparently bully foxes out of their territories, called interference competition study, another study found that a third of kit foxes radio collared had been killed by coyotes, study)
  • As a result, foxes can be found on the edge of a coyote's territory, but rarely within it
  • Foxes out-compete coyotes in areas where human densities are higher
  • Many predators will kill other predators (canids, it turns out are the most likely predators to kill other species of predators: study)
  • More foxes=less Lyme disease, more coyotes=more Lyme disease (study)
  • Red foxes have a significant impact on the European Roe deer, but those are much smaller than our native deer and it's likely that no such correlation exists
  • Coyotes have a significant impact on deer populations (study)
  • Coyotes are more successful in hunting deer in harsh winters (study)
  • There's no hunting allowed in Burlington, so deer populations may be higher here as a result
  • Deer seek refuge under conifers during winter for warmth, both habitats provide an abundance of hemlock cover, however

Tuesday, February 26, 2013

Rabbits are what they eat

Rabbit debarking bittersweet (all photos in this post by Zas Ispa-Landa)
What: You are what you eat. And in this case rabbits are a whole lot of things. Zac and I were impressed at the abundance of rabbit sign (from the introduced eastern cottontail, Sylvilagus floridanus, as opposed to the native New England cottontail, Sylvilagus transitionalis) when we went tracking on Saturday down at Bread and Butter Farm in Shelburne. We even spooked a cottontail as we walked past the driveway. Rabbits seemed to prefer shrubby non-natives, or at least those were the most prolific species in the area and so were the most foraged upon. We found feeding sign (debarking and/or twigs clipped) on forsythia, common buckthorn, barberry, domestic apple, honeysuckle, staghorn sumac, and oriental bittersweet.

45o angle snips on twigs, charateristic feeding sign from cottontails
on woody species (forsythia in this case)

The story got even cooler at the end of the day when we found another high traffic area for cottontails under the powerlines. Buckthorn predominates in that area and the rabbits must have been eating fallen buckthorn berries as their urine was died blue (image on the right is blue tinted urine, on the right is more typical orange). Buckthorn berries are unpallatable, if not inedible to most things so the berries persist into late winter, when they become a last resort for many winter active species.

Ecological notes: Many plants contain phenolics (tannins, which cause the dry taste in wines, the bitterness in aspen bark) as a defense against herbivory. During spring and summer these are concentrated in leaves and flowers, but during winter they are translocated to the bark. Animals have a variety of ways of dealing with these phenolics (e.g. beavers will soak witchhazel before eating to leach tannins, birds and will eat clay, which absorbs phenolics). Buckthorn (Rhamnus cathartica) is high in phenolic compounds. Rabbits presumably can handle the phenolics by breaking them down in their kidneys, or maybe eating clay. The anthocyanins (pigments in the fruits) are also excreted in the urine. I'd assume that eating buckthorn fruits later in the season gives more time for the tannic acids to break down and makes the fruits more palatable. That's speculation though, and I couldn't find any articles to confirm/deny that.

Saturday, February 23, 2013

What do foxes eat?

What: A couple nights ago, Meryl, Julia, Brian and I were watching a couple of eastern cottontails chasing each other ferociously around in my backyard. For the 3 or so minutes we watched, one was definitely the pursuer. They would sprint for short periods followed by great acrobatic displays with one or both jumping straight into the air. Their breeding season is March through September, so this might be an early start on staking out breeding territory, a mating ritual between a male and a female, or it could be a late winter food-shortage spat. I'd only ever seen one rabbit at a time in my backyard so I didn't realize that their territories overlapped. I have no idea of gender, nor is there a reliable way of telling without having the animal in hand.

I left some food out to bait so I could get a photo of at least one of the rabbits. For the hour or so I watched the rabbit from my window, it spent about 95% of its time in surveillance mode and the other 5% eating, moving, or grooming. I love the above photo, because it shows those great big back legs and stubby little front legs.

Where: My backyard

Other notes: Eastern cottontails (Sylvilagus floridanus) are virtually identical to the native New England cottontail (Sylvilagus transitionalis), and can only definitively be identified if the animal is dead (genetics or skull morphology). NE cottontail populations have declined since Eastern cottontails were introduced to Vermont over 100 years ago. According to a publication on Eastern cottontails produced by Vermont Fish Wildlife, wildlife agencies and private hunting clubs were responsible for the introductions. Rabbit populations have declined as a whole over much of New England due to reforestation and loss of transitional habitat.

Wednesday, February 20, 2013

At the end of every trail...

What: Brian came downstairs yipping about a red fox in the parking lot. A minute later Meryl came down equally excited. We threw on our shoes and headed out into the beautiful snow. We picked up the tracks circling along the edge of cedars then along the powerline substation by UVM Facilities office and Centennial Field. In the photo below the fox demonstrates a near perfect direct register trot. In this gait the animal's rear foot lands exactly where the front foot landed. The 3rd, 5th, and 7th prints appear wider where the animal slips from the direct register just slightly. The front foot, which is larger (as with all canines) and appears under the imprint of the rear foot, is offset to the right, where the fox was probably looking to the right (up the road to East Ave).

We came to a very very small crack in the fence that it had scooted under. Weirdest thing is to think how that little opening got there, as it seemed deliberate. Could the foxes have worked up the fence over time? It'd be tough for even a human to bend that fence. The fence is other wise in perfect shape and it's on the side that doesn't have any traffic so it's hard to imagine it accidentally getting formed. Regardless, it makes for a nice escape hatch (as when being pursued by a pair of humans).

On the east end of the substation, there's another gap in the fence that the fox slithered through before making its way down the rocks towards the dumpster. See if you can spot the fox in the image below. Brian and I watched the fox for a bit tugging away at the ground before slowly stalking up on it. 

As we got closer, it looked like it was trying to get under the plow. When we got about 35' away we scared the fox off and were able to investigate what it was investigating. We found a dead squirrel tangled in a pile of trash (smelled really really bad). The fox ran around the fence and hid under the building you can see in the above image.

Where: UVM Facilities/Centennial Field

Other notes: As we approached another fox of equal size got spooked and headed over to the south where the mulch piles are. The weirdest thing was that the fox was white. Or rather, it seemed like a darker colored fox that had its coat covered in snow. Brian and I were both covered in snow after being out about 30 minutes, so not unlikely, but still seemed weird - albino foxes in CW?

Monday, February 18, 2013

Snake mountain and lake closings (freeze overs)

What: I hiked up Snake Mountain with Jon and his family yesterday. Looking out at the southern end of Lake Champlain, I was surprised by how the sharp line at the edge of the ice was. The ice seemed to be corralled into the southern bay, perhaps by the harsh northerly wind. The freezing point I think was between Potash Bay in Addison, VT and Mullen Bay near Westport, NY.

The image to the right shows data collected on the lake between 1816. Rectangles on the left side, colored in red, indicate years in which the lake did not freeze over completely at the widest point (from Burlington Bay across the lake about 9 miles to Corlaer Bay; 6 miles if you don't include the 2 bays).

In total, since data collection began, the lake has not frozen over 38 times in the past 197 years. 32 of these are in the last 54 years! While it might be convenient to readily assume that climate change is the culprit, there might be some confounding factors that have also changed over the past 197 years. Things that lower the freezing point of water could include increased:
  • Turbidity (suspended solids absorb more heat from sunlight)
  • Wind
  • Turbulence (like flow in a river)
  • Concentrations of salt, alcohol or any other substance that has a lower freezing point than water
I don't know for sure if these have any bearing on the fact that the lake is consistently less likely to freeze over, but they are likely a part of the story. I found an article from Feb 15, 1993 in the Daily Gazette about Lake Champlain closing dates (when it freezes over completely). The article states:
"Whether the lake freezes over or not has no effect on the fish and other creatues that live there, said George LaBar, a UVM fisheries biologist. 'The bays are always going to be frozen, those shallow areas are going to freeze over,' and the fish who live in those bays are used to that, he said. A frozen lake doesn't affect teh overall temperature of the lake water, he said. Winters with less ice cover might encourage fish to spawn earlier, he said, which allows the young fish to grow larger."
I really doubt that the lake not freezing over has no effect. I think it probably means something pretty significant for some things and not so much for others. Complex system with complex feedback loops.

Saturday, February 16, 2013

How hemlocks breathe

What: I used to describe the underside of a hemlock needle as being akin to an old classic longboard surfboard. It wasn't until a few years ago that I actually wondered what those little white lines on the underside of a hemlock needle actually were.

Ecological notes: Those two white lines are actually a bunch of little white dots, which are actually the stomata (the mouths, or sites of gas exchange, in leaves).

Because conifers weather out the winter with their needles still on the branches, they have to compete with harsh winter winds for water. They effectively have a water input of zero. With the ground frozen, the tree can't replace any of the water it might lose to transpiration (basically evaporation of water out of any openings in a leaf). Transpiration increases with wind that would carry water vapor away (much like how you can tell wind direction by licking your finger and holding it up; it feels cool on the windy side because the water is evaporating even though it's well below the boiling temperature where you'd expect it to go from a liquid to a gass).

Hemlocks would risk desiccation (severe drying) in the leaves unless it could somehow protect itself from the ways it loses water. It does this in a couple of ways. First, it has a super waxy cuticle. The waxy cuticle prevents transpiration from occurring on the top side of the leaf. Second, it protects the stomata (those openings) from being exposed to the wind by putting them on the underside of the leaf and having them in grooves.

Tuesday, February 12, 2013

Not so Wild Burlington

What: I've wanted rabbits since I knew what a rabbit was and I've been knitting for about 7 years. Recently my sister mentioned angora rabbits and I thought how amazing it would be to have my own source of wool. I did some research and started obsessively checking craigslist for listings. I wound up finding a pair of females from a great family in Essex Junction. The little sweethearts are a mix between French and English breeds. We're still not sure what to make of them other than that they're impossibly adorable.

Peanut (left) and Sister (right) eating snow off the floor

Where: My porch!

Other notes: One of the most interesting facts I learned about angora rabbits was that in World War II, Nazis started the "Angora Project" to raise rabbits for their wool. The wool, about 6-7x warmer than sheep wool, was used to line the jackets of Luftwaffe pilots. A wool bound book, Angora, was found at the farmhouse of Heinrich Himmler, among other possessions of his stashed away towards the end of the war. The book was a hand-crafted photo album carefully inscribed with notes on the rabbits.

Himmler, a reichsfuhrer - highest ranking member of the SS - said in a recorded speech about Nazi's angora project: "We shall never be rough or heartless, when it is not necessary; that is clear. We Germans, who are the only people in the world who have a decent attitude towards animals, will assume a decent attitude towards these human animals; but it is a crime against our blood to worry about them." Prisoners, who were housed in conditions overwhelmingly undersized and in everywhere debasing, cared for the rabbits, who were kept in comparative luxury and used as a showpiece for visiting dignitaries. Prisoners were punished severely (even killed) for mishandling the rabbits. It's an unbearably sad story, and hard to reconcile the aggressive callousness for human life with the overlapping tender fondness and hyperbolic appreciation for these animals.

Monday, February 11, 2013

Winter Storm Nemo time lapse

What: It didn't turn out nearly as well as I had hoped, but on Thursday night I set out my camera to capture a timelapse of the incoming winter storm Nemo. If you look at the pallet at the bottom of the screen you can see rise in snow as it accumulated. The winds knock off most of the snow from the trees by the second day.

Where: My backyard

Other notes: Meryl pointed out to me that winter storms only recently started being named storms. The Weather Channel, aka, published a press release explaining their new self-appointed role of winter storm namers. here's an excerpt:

"During the upcoming 2012-13 winter season The Weather Channel will name noteworthy winter storms. Our goal is to better communicate the threat and the timing of the significant impacts that accompany these events. The fact is, a storm with a name is easier to follow, which will mean fewer surprises and more preparation. 

Naming Winter Storms
Hurricanes and tropical storms have been given names since the 1940s. In the late 1800s, tropical systems near Australia were named as well. Weather systems, including winter storms, have been named in Europe since the 1950s.  Important dividends have resulted from attaching names to these storms:
  • Naming a storm raises awareness.
  • Attaching a name makes it much easier to follow a weather system’s progress.
  • A storm with a name takes on a personality all its own, which adds to awareness.
  • In today’s social media world, a name makes it much easier to reference in communication.
  • A named storm is easier to remember and refer to in the future."

Sunday, February 10, 2013

Wind crusts and all that snow

What: I went for a walk with Jon yesterday and while there was certainly a lot of snow on the ground, almost all of the snow in the trees had come down. I started thinking about all of the other ways I might observe wind. I was at Rock Point Friday night and by Saturday morning the winds had picked up and cleared out the thin layer of slush in Little Eagle Bay (what we call Mink Bay) and replaced it with stacks of ice plates. The winds picked up all day and by the afternoon they were stinging our noses. Because of the cold, the snow was "dry". But the wind had dried the snow right up, and sure enough it slid right off of railings, my car, and anything else it was perched unto.

The dryness of the snow meant that by late morning almost all the snow had come down off the deciduous trees and conifers that weren't sheltered by other conifers. I tried to capture the grace of snow clouds drifting whimsically through the woods but couldn't quite get it. I think it needed video.

Deep wells had formed at the base of most of the larger trees indicating sustained unidirectional winds that had carved gullies where eddy currents downwind of the trees. The trees all had gullies on the south sides, and sure enough our winds were out of the north.

Jon commented on the lack of scale with snow. I think topography is one of the easier things to confuse my sense of scale. Looking at ripples in the sandy basin of a river I can easily imagine running across sand dunes. Looking down at a snowy aster poking up through the snow I was immediately transported out onto the vast open tundra.

Ecological notes: Crusts on the top of snow form in three ways. 1) Sun crusts (aka spring crusts) form when the sun melts surface snow, which then refreezes. 2) Freezing rain: supercooled rain falls and freezes when it hits the snow surface, forming a solid crust (other surface water processes could be included here), and 3) wind crusts, which form as wind breaks up flakes and packs them together.

Tuesday, February 5, 2013

Beyond maple syrup

Spiles: (L to R) elderberry, sumac, late 1800s model, 1950s model
What: 3 years ago, one of my students told me about her family's sugaring operation in New York. While talking to her I realized I'd never had straight sap before. That semester, Bekah brought me a 20 oz bottle filled with the sweetest water I'd ever had. Wanting to tap my own trees, the following year I bought some spiles (the taps) and buckets. I don't have any sugar maples (Acer saccharum) in my backyard so I decided to try and eke some sweet syrup out of the trees I do have.

Embarassingly out of focus shot of the ESS group
carving their own sumac/elderberry spiles 
Yesterday, with the Earth Skills Seminar, we tapped 13 different species:
  • Norway maple** (Acer platanoides)
  • Boxelder (Acer negundo)
  • Silver maple (Acer saccharinum)
  • Red maple (Acer rubrum)
  • White ash (Fraxinus americana)
  • Apple (Malus domesticus)
  • Big-toothed aspen (Populus grandidentata)
  • Black cherry (Prunus serotina)
  • Hackberry (Celtis occidentalis)
  • Black locust** (Robinia pseudo-acacia)
  • Smoke tree** (Cotinus sp.)
  • Black walnut (nigra)
  • Paper birch (Betula papyrifera) Zac thinks it's a gray birch, but we'll see.  

We're planning on tapping European larch (Larix decidua), red oak (Quercus rubra), staghorn sumac (Rhus typhina)**, and a buckthorn (Rhamnus cathartica)** as well.

** I would categorize all of these species as potentially disgusting to mildly toxic. Both smoke tree and staghorn sumac are in the cashew family (Anacardiaceae), and members of this family have sap that is purportedly toxic. So rather than attempt to make syrup out of the more toxic species, one of my hopes is to get a sense of when the different species have their sap flow relative to the other species. From here, I'd like to find correlations to different characteristics of each species (like habitat range, simple vs compound leaves, ring-porous vs diffuse porous, etc.).

I'll post results of our experiment as they emerge!

Also, I included Norway maple in this list even though the sap is perfectly edible. Trees get "buddy" by the end of the season as they shift from sending sugar/nutrients from the roots up to the twigs to producing chemical defenses. During the summer a broken Norway maple leaf stem will ooze a milky white sap, which tastes terrible. As the early spring sap flow progresses, the sap of Norway maple shifts to being murkier and fouler. I would assume that at this time they're ramping up defenses for the emergence of flying insects and other would-be predators.

Other notes: One thing we said at the Earth Skills Seminar today is that we won't talk about edible/medicinal things that we haven't ourselves tried. I read a lot of bogus stuff on the internet about different saps - a lot of people just citing other unreliable sources. What we hope to do here is take calculated risks to know for myself what is and what isn't a reliable source of sap each spring.

Sunday, February 3, 2013

Hemlock, the patient one

What: Even with the leaves off the trees and sounds (particularly I-89) filtering through the woods with reckless abandon, there's still a peacefulness to the movements of the woods in winter. While walking across the Winooski Bridge I admired the slow undulating flaps of a Cooper's hawk above and the odd oscillations of the water bubbling back and forth off the ice as it came to a halt in front of the dam. The hawk flitted gracefully to the west, cut a quiet line through dense air and alighted on a distant smoke stack.

There's an equal grace and peacefulness to the slow bending of a hemlock - what I call the Winter Tree - under the sway of the wind. Among the conifers, hemlock stands out to me as such a delicate and deeply cold tree. The rich green of the foliage feels more like the shadow of a leaf, like the tree was born in winter only to endure summer each year.

The branch above is about 2 3/4" across

Enduring the summer means slooooow growth. I was out harvesting wood for coasters, and I found a giant old hemlock that had come down across Wool Pullery Brook in South Burlington. I cut the branch from the trees in the photos at the top (about 35' from the trunk) right at the base where it came off of the tree (if the tree were still standing the branch would have been about 25' up). Hemlocks are about the most shade tolerant species, and a single hemlock needle can live for up to 40 years (in part because it can deal with as little as 10% light and still photosynthesize enough for the plant to keep it around; for contrast, white pines are far less tolerant of shade and lose about half their needles each year).

I guess I shouldn't have been, but I was surprised at how ancient the branch was given its size. It was too hard to count the rings by eye so I sanded and finished the "cookie", photographed it, then ramped up the contrast. Each arrow represents 10 years of growth. The rings were extremely tight, and there's a distinct boundary between the heartwood and sapwood (sapwood is the lighter section of rings on the outside). The branch was much less resinous farther out, indicating that the distinction was largely due to the tree needing extra support in holding up that branch for 106 years.

Where: Hemlocks grow at extremes - there are hemlock swamps and there are steep rocky hemlock slopes. It can grow in the shadiest of places, less than about 10% light. This tree was growing along Wool Pullery Brook in Centennial Woods.

Friday, February 1, 2013

The Three Hares

What: Welcome to a new series of posts I'm calling "The Three Hares". On the first of each month I'll be posting a 15 second video of the same spot. My sister and I went out to Centennial Woods yesterday to scout out a place to film. It was a little daunting because in ten years from now I want to reflect back and be happy with my choice. I wanted the spot to be open and have water flowing through it. I wound up choosing two perspectives in case the sumacs in the above video block out the perspective. Enjoy!

Where: The confluence of Centennial and Wool Pullery Brooks.  

Other notes: The Three Hares name is a riff on Rabbit Rabbit Rabbit (also "White Rabbit") - a superstition that started in the early 1900s. Supposedly, saying the phrase (or some iteration of it) before anything else on the first of the month brings good luck. The iconic three hares motif (a depiction of three hares chasing each other in a circle, each sharing an ear with the other two rabbits) may be the inspiration for the superstition. The three hares motif is an ancient Chinese symbol, with the first known etching dating to the 6th century. Most of the ancient examples are along the Silk Road, and there's speculation that the motif was brought to Europe by merchant traders in the 15th century. The symbol is featured in prominent places in a number of churches in England.

Rabbits are often seen as a symbol of good fortune, and I can imagine a little English child sitting in church learning about all the ways she'd done wrong, sinning and such, and felt like she needed a little bit of good luck on a dreary winter day. Perhaps she'd imagine follow a most curious white beast down its rabbit hole. Much like the Easter bunny brought tidings of spring, warmth, love, rejuvenation, the rabbit of her imagination would bring her hope, happiness, and warmth. Since she couldn't get a rabbit's foot to wear as an amulet, she and her younger brother came up with a little ceremony to ward of bad spirits for the whole of the month. It offered risk and adventure - what if they forgot - would they be cursed? - and also made all those odd symbols around the church make a little more sense, at least in their own little way. So some creative license, but why not. Rabbit Rabbit Rabbit.