Monster of the dill

What: Last night I spotted a black swallowtail caterpillar (Papilio polyxenes) on our dill. When I came back this morning it was still there, perched on the same delicate pedicel (fancy name for the stalk that connects a flower to the main stem of the plant) of the dill's umbel (fancy name for an inflorescence [fancy name for a cluster of flowers connected by a central stalk to the main stem of the plant] where the flower stalks are of equal length and extend from a central point).

Prolegs on left, 6 legs on right

Ecological notes: I read two things about these caterpillars. The first is that they can decimate a patch of dill when their populations erupt, and they often do, in near biblical proportions (exaggeration, but warranted for gardeners with an affection for dill; in the photo to the right you can see all the "missing" flowers at the tips of the pedicels from where the munchkin gnawed them off). Many of their would be control-mechanisms, like birds, are thwarted by what's called an osmeterium, a weird little forked appendage at the front of the thorax (just behind the head). When provoked the caterpillar will rear up dramatically on its prolegs extend the osmeterium and emit a most rank and foul odor. Well, I had to test this out myself. I didn't smell anything except freshly cut dill (you can see a bunch of flowerless stalks that the caterpillar had nipped off), but what a beautiful treat! Perhaps the vibrant orange signals as a warning before emitting the odor, much like a skunk stomps its feet, chatters its teeth, and does a handstand before finally spraying an approaching predator.

Where: My backyard

Etymology notes: The root "osme" comes from the Greek ὀσμή, or "to smell" and the suffix "-rium/-ria" indicates a place or building (e.g. atrium, cafeteria, solarium).

The Weird World of Mollusks

What: I don't think I'll ever be able to fully empathize with a mollusk, well at least not with a bivalve. But I do find them terribly fascinating, which isn't a bad start. And like most things, the more I learn and observe them the more I appreciate their quiet existence. While walking the shoreline at Delta Park, I was caught by the odd swirling groves etched into the sand. I had been spending some time trying to figure out how different water currents would manifest in the topography of the underlying sand - in some patches there were long straight furrows like a recently plowed field, while others had overlapping u-shaped mounds consistent in size for a given patch (see end of video for what I mean). I couldn't help but be distracted by the seemingly chaotic lines that the clams had carved across the ripples.

Ecological notes: While walking barefoot through the shallows, we didn't have to worry much about zebra mussels at Delta Park because the substrate is largely sand. Mussels are a subset of clams (see etymology notes below) that have byssal threads that serve to anchor their shells to a solid substrate - no solid substrates, no mussels. Only in a few places, like where we found heaps of downed trees partly submerged in the water, did we find zebra mussels. We did however find an abundance of freshwater clams. I unburied one, then left it with my camera set to take a picture every minute and a half. The time lapse was shot over about an hour and a half. In the first few seconds you can see the animal expel a mess of waste, which appears to be attached by a string.

There behavior still largely mystifies me. With their large rubbery foot the clams slowly reposition themselves along the shoreline - perhaps following changes in wind direction, water depth, or some other factor. Some of their trails were long slow arcs, others overlapping and confused circles. The groves left behind in the wake of their movement created small eddies in which algae settles. Fresher trails appeared as gray fissures bordered with crusty plates of sand fragmented. I checked some of the same trails after about 12 hours and they looked largely in tact, so I'm guessing it takes some stronger currents to breakdown the trails (and that they move really really slowly).

Smaller bivalves burrowed in sediments. Water level is super low right now

Their trails in the sand (hard to see unless you click on image to see a larger version).

Algae settled in old tracks

Where: Delta Park in Colchester (mouth of the Winooski River).

Etymology notes: The term clam is a muddy one to say the least. A clam could be a bivalve (a mollusk with a pair of hinged, clasping shells) that burrows into sediment - as opposed to a mussel, like a zebra mussel, which attaches itself to a substrate like pilings, other bivalves, whales, or just about anything else with a solid surface.  Or a clam could be an umbrella term for all bivalve mollusks (a square is always a rectangle, but a rectangle is not always a square like a mussel is always a clam but a clam not always a mussel). When I called ECHO to ask about help identifying freshwater clams, I was corrected: "freshwater mussels," which further confused the matter since I was referring to bivalves that burrow in the sand. Maybe there's a vernacular understanding of "mussels" as any of those freshwater filter feeders.

Other notes: Not sure about the edibility of the mussels, but they seemed an enticing source of food. Mussels themselves are not toxic, but they are filter feeders so you're essentially eating whatever microscopic stuff is floating down the Winooski or hanging out along the edges of Lake Champlain). Plus I'm not sure what species they are. Vermont's Wildlife Action Plan says that of the 18 species of mussels in Vermont, 13 are listed as threatened, of special concern, endangered, or already extinct (a rate on par with national figures). I used a field guide from Connecticut to try and ID these guys, with little luck. There's another publication UVM has that I plan on checking out to try and narrow it down: Fichtel & Smith's The Freshwater mussels of Vermont. Plus, depending on who you talk to, some species can live 75-200 years. I'd feel bad eating something that old.

The Clouds and the Lake

What: I've now paddled the Salmon Hole to downtown Burlington loop about 7 times, this last time with my sister, Meryl, and our friend Carlos. It's amazing that I can walk my boat three quarters of a mile, paddle, 16 miles, and then walk 2 miles home. With all the rain we had the other night the river level was considerably higher and I had a blast running the rapids at Salmon Hole. The wind was also much stronger. The following day (Wednesday) we had fair weather, with a nice blanket of cumulus clouds settled over Vermont and New York. With a different perspective of being on the lake I was struck by the noticeable absence of clouds over the water.

Panorama showing absence of clouds over Lake Champlain

Ecological notes: My theory is that we had lots of rain on Monday, followed by warm temperatures. Already when the rain was falling it was evaporating and there was a beautiful mist carpeting the understory of Centennial Woods. As the warm moist air rises it reaches cooler air. When enough water vapor cools enough degrees (the birds and bees of making a cloud) it can reach what's called the dew point. Dew point is the point just beyond 100% relative humidity where water vapor condenses out onto a solid substrate, like dust or grass or your tent. An easy example is a cold glass of water on a warm humid day. As the air comes in contact with the glass it cools rapidly. Cold air can "hold" less water vapor, so the air in contact with the glass reaches the dew point and little water droplets form on the glass (but not on your much warmer skin). 

In the atmosphere, as that warm air rises, the water vapor can condense and will appear to us as a cloud. So the greater the difference in temperature between the ground and the sky, the lower the elevation at which clouds should form, because they'll reach that dew point much sooner.

We started paddling on the lake around 9:45am and I guessed the clouds were around 3000'. Once we rounded Apple Tree Point we had a great view of Camel's Hump and a little more than the summit (4081') was covered, so the clouds were probably closer to about 3500'. About an hour later it was considerably warmer outside, and more warm air had already risen into the atmosphere, thus, the air around Camel's Hump had warmed as well. This should have raised the dew point and the elevation at which clouds were forming. Sure enough, by about 11:15am, the top of Camel's Hump was exposed, indicating that the clouds were at about 4100'.

So why no clouds over the widest parts of the lake? The temperature of the lake is more stable and cooler, so the temperature gradient between water and air is far less. Because there is a lower temperature gradient, the air rises at a much slower rate, allowing for water vapor to reach equilibrium rather than condensing out.

Where: Lake Champlain & the mighty Winooski River

Other notes: The sunlight on Tuesday was stunning - those soft sunset golds. The winds were kicking up the leaves of the silver maples that line the Winooski River. I could never understand why they were called silver maples until I saw this a few years ago. The undersides have a much paler color and when the winds dance them around exposing their bellies the whole tree takes on this ethereal silvery sheen. Someone must have named it in the sunset after a good summer storm.

Bees and gender in Insects

What: I've been thinking more about my last post and the importance of words in relation to our understanding of the world around us. I was telling a friend about the woodchuck that's growing fat off our kale, and how he had gotten the broccoli too. My friend asked how I knew it was a "he" and then pointed out how it was weird that animals automatically and unconsciously becomes "he" when the gender is unknown (I'm always conscious of when someone uses the pronoun "she" in a gender neutral situation). The pronoun "it" lacks so much emotion and humanity, like describing an automaton, so, because we like to anthropomorphize animals (e.g. Bambi), we assign gender to them. I even hear people refer to my bees and egg laying chickens as male.


As a naturalist my first questions are often around identification, particularly with insects. I posted an ID request to the bugguide.net community. John Carr sent a response "It's a female dolichopodidae." Well female is awfully specific, but animal scientific classifications ending in -idae (-aceae for plants) are family groupings, which are pretty general (Curculionidae, the weevil family, contains over 40,000 species). This is from a guy who specializes in IDing midges and their relatives, and he could get gender but only ID down to family. So what was he cuing into that said female and not male? Turns out the answer is more about what makes a male a male.

Ecological notes: So even with the vast evolutionary divergence of insects into every ecosystem around the world, some morphological adaptations are still conserved or at least have converged. One of those things is a male's ability to detect a female, and they do this in a variety of ways, like hearing, smelling, or seeing females from a great distance. Male mosquitoes, for example, have enlarged antennae to pick up that horrendous and penetrating bzzzzzz sound the females make as they look for that perfect patch of skin. What I'll call foot moths (and cover in a future post) have huge antennae for "smelling" the sex pheromones from females.

Male honeybees, aka drones, have enlarged eyes to spot a queen before other males do. The first picture in the post is a drone; note how the eyes are so big that they actually touch in the middle of the head. The next picture shows a bunch of females at the entrance to the hive, their eyes considerably smaller and not touching on the tops of their heads. Drones are pretty much useless to the colony other than for reproduction. They hanging around feeding on honey, begging for food, and grooming themselves. When the timing is right they'll start going for exploratory flights to breeding sites. These change frequently, so a male needs to be able to spot one from a distance. The story is far more complicated than this, but it's a neat start and I"m tired, maybe more later...

Where: My backyard

Other notes: Ryan Morra and I noticed a whole bunch of female worker bees crawling around on the ground near the hive. I went back with my camera after he left and spotted one a worker dragging another, much lighter colored worker out of the hive. At one point the lighter one started to fly and the other one held on and pulled it back down. Once it got to the edge of the platform the darker one left the lighter one to die on her own. In the middle of summer, this generation of worker bees have the shortest lifespan of just a few weeks (c.f. winter life span can be several months). Kicking out unproductive bees is essential, I guess, to maintaining efficiency.

A gaggle of nouns

A deer stopping for water in the 90 degree heat

Where: Winooski River (still). Zac and I just got back from another paddling adventure to complete my last trip from Bolton to Salmon Hole, this week from Salmon to Skinny Pancake. Another perfect day of paddling!

An outburst of water striders

Other notes: This time of year has the most overlap across life stages for animals. You may have noticed not just one crow perusing the lawn for food, but a mini-flock of 4 or 5, or a sudden flush of 30 robins sweeping through a honey suckle thicket. As nesting season winds its way down (com on goldfinches, hurry up and finish nesting already), lots of family groups are out and about feeding, the males are less territorial trading the stress of land disputes for the comfort of extra sets of eyes to be vigilant. It was hard enough on the trip to identify the many different species of birds, flowers, and trees I was passing by. Throw into the mix the different names for males, females, juveniles, and even collective nouns, and I was a bit over my head trying to keep it all straight. I got curious about what the different names for groups of different animals might be (and is there a term for a herd of cottonwoods? a "stand" is so boring, "grove" gets better, but there's a whole world of opportunity here).

  

A scuttling of mergansers

A motoring of ducklings

  

A ring of ring-bills

A dastardly of F-16s

I've long been fascinated by names and the naming of things. I was first introduced to the quirks of latin names by my love of gray squirrels, and indeed Sciurus carolinensis was the first scientific name I learned. Turns out Sciurus derives from the Greek words skia (shade) and uros (tail). The Greeks must have thought that squirrels their tails much like one might find respite from summer heat under the cover of a parasol. They were wrong, but thanks to the convention of naming things, their error is preserved in our scientific lexicon.

A flapping of kingfishers

Contemporary naturalists seem to have a certain fondness for collective nouns used to describe groups of animals. Being able to call a flock of crows a murder, starlings a murmuration, or vultures a committee is a sure sign of esoteric adeptness when it comes to being naturalist. It's like the painfully obvious difference (to those in the know) between a tourist ("Bar" for Barre, "Shar-let" for Charlotte) from a Vermonter ("Bare-ee", "Shar-lot"). There is delight, beyond proving ones worth in the often ridiculous and colorful phrases. Some are probably grounded in some sense of the animal's natural history, while others, it appears, are from the fanciful imagination of the 15th century British author Dame Juliana Berners, or at least were first recorded by her. She was the prioress of a nunnery, where she kept up her passion and dedication to fishing, hunting, and other outdoor pursuits. Her book, The Boke of St Albans, is damn near impossible to read (much like Canterbury Tales). It includes three sections - on falconry, hunting, and heraldry. In her section on hunting she publishes a lengthy list (3 pages worth!!) of collective nouns. The most famous to make it from her pen to our vernacular is murder of crows, but the rest are just as inventive.

A lonesome of bald eagle

It might be easy to chalk the lengthy list up to the poetic musings of one more skilled in writing than shooting, but I think Berners, like other hunters, had stories that got bigger and bigger with time: "I once caught a fish th-------------------------is big." I imagine that sport hunting was a hobby for the finer and fancier of folks, a well-educated bunch that would lounge around the hearth in their parlors recounting hunting tales from days of yore. "If you think today was good, you should've been here yesterday, we caught a suit of mallards, a muster of peacocks, a covey of partridges, and a bevy of girls."

A hawking of kingbirds

Language reflects what's important to the culture that uses it. Thus, the Yup'ik Eskimos, for example, use the word kanevvluk for fine snow particles, natquik for drifting snow, aniu for snow on the ground, and have other distinct lexemes (like a root word) for variations of snow. So if your culture values hunting and the pride that comes with it you might expect a distinct lexicon to accompany it, much like any subculture develops its own language to describe shredding the gnar, sick pow-pow, etc.

An awkwardness of herons

Since her writing, many more collective nouns have sprung up, some useful and serious, others amusing and useless (a clutch of auto mechanics). In the captions for each picture, I've thrown my hat into the ring, vying for a few new collective nouns.

A flotsam of jetsam

As a side note, the publishing of Boke of St Albans made Berner the first published woman in England.

Berner's list of collective nouns in its original format