I stopped running because I was surrounded by hundreds of crows. It was dusk on the bike path along Lake Champlain. Great masses of crows were flying in from the east to roost on the cottonwood trees along the shore. They fed on sumac fruits along the train track; they mobbed the tree-tops and hop-flew from one twig to the next; they perched all over the bare branches of the trees. In the light of the setting sun, their black feathers shone glossy and strong. More kept arriving almost continuously from the east, flying in over the barge canal. As they flew in they gave these weird, multiple-part calls, not at all like the usual “caw-cAW-CAW!” What were they saying and why were they gathering here? Continue reading
by Danielle Owczarski
I am standing on a deserted public beach in Burlington, VT, situated west of the bike path and the Burlington Electric Department. My husband and I, dog in tow and cameras in hand, are in pursuit of stories told by the natural world; those neglected by people behind weatherproofed door jams. During the winter months, protected by the shelter of my apartment, I cannot tune out the arctic breeze whooshing against my door. I imagine the biting wind flowing through my veins, breathing life into my limbs, pushing me to be a part of the world beyond my warm, snug box. Once outside, the indoor fog in my mind lifts and my periphery expands initiating a new awareness. I enter the natural world to feel alive. Continue reading
by Audrey Clark
My stepbrother lounged in front of the television watching a reality TV show about mining in Alaska. I sat on the couch, facing away from the television, drinking tea and reading a book on visionary scientists.
After a while, I started to wonder what my stepbrother wondered about.
“What questions do you have about nature?”
Then, in an outpouring I wouldn’t expect from a non-naturalist, let alone one who was watching TV:
“Can plants feel pain? How does a woodpecker not get a concussion? How do you tell how old a tree is without cutting it down? How long does it take ants to build an ant hill? Where does honey come from? Like what part of the bee? What’s the best way to survive a bear attack? Can animals get sick from drinking bad water like we can? Why do monkeys have better immune systems?”
In honor of my stepbrother, here are my best attempts at answering these questions: Continue reading
I came in to my cubicle at school last week to find a maggot squinching across my desk. After a moment of shock and disgust, I thought, “Ooh! What a nice present!”
You know you’re a naturalist when finding a maggot among your things makes you happy.
I’ve been collecting insects, so I naturally thought that one of my classmates left the plump grub for me to add to my collection. Surely it hadn’t come from the pile of soil samples I had on my desk, nor the cache of snacks I had in the cabinet. But yes, it had. I had collected a handful of red oak acorns and left them in an open plastic bag on my desk. Later, when I was working at my computer, I looked over and saw a pale yellow grub with a red face squinching around inside the slippery plastic among the acorns. I examined the nuts and discovered a hole in one of them, about 3 millimeters across.
That was when I got really excited. All I had to do was feed the little creatures and keep them happy, and I’d eventually find out what species they were. So I dug around in the faculty kitchen for a plastic takeout container, poked some holes in the lid with a pen, dumped my soil samples into it, and dropped the acorns and grubs on top. The grubs promptly burrowed out of sight. I labeled the whole thing with a permanent marker, “Happy Maggot Land, Please do not disturb.”
Then I started to worry about my maggots. What if the soil wasn’t enough to make them happy? Did they need something to eat?
I visited Jeff Hughes, the director of the Field Naturalist Program, who recommended I look in Tracks & Sign of Insects and Other Invertebrates, a recent book by Charley Eiseman, an alumnus of our program, and Noah Charney. I thumbed through and found the name of my maggots: long-snouted acorn weevils.
The female of this beetle species saws a hole in the shell of a red or white oak acorn and lays her eggs inside. The eggs hatch in a few days and the larvae eat the acorn meat. Beetles undergo metamorphosis like butterflies do; caterpillars are butterfly larvae, maggots are beetle or fly larvae. They molt five times inside the acorn and then leave their nutty shelter and burrow into the soil to pupate. Pupation in beetles is analogous to the caterpillar cocoon: a usually immobile stage of metamorphosis just before emergence as an adult. In the spring, adults emerge from the soil and fly off to mate before beginning the cycle again.
I have named my maggot friends Weevil Kneevil, Do No Weevil, and Axis of Weevil, but I have no intention of keeping them. I plan on releasing them back into the forest to continue to parasitize on oaks. It’s not because I don’t like oaks, but because I like ecology. These weevils create food for other species: one genus of ant lives inside acorns abandoned by weevils and eats the leftover meat. Squirrels eat acorns sometimes just for the grubs inside—that’s one reason why you might find partially eaten acorns.
Having maggots as pets helps me see more when I go outside. I see potential Happy Maggot Lands everywhere—inside plant stems and fruit, in dying tree trunks, and in the soil under my feet. A new way of knowing the world around me has opened up.
Written by Rachel Garwin
A week ago, I joined my friend Teage (a Field Naturalist alum) and a group of his UVM students on an “owl prowl,” Teage’s own euphonic term for a night hike. We gathered at the edge of Centennial Woods, where gauzy tufts of white pines and bare hardwood twigs strained the clear moonlight. A wall of darkness met our eye-level gaze, while the raspy sounds of drying beech leaves in the understory added to a sense of disquiet. The primary goal for the evening was to listen for flying squirrels and call them in. Before we entered the darkness, however, we observed a requisite pre-night-hike ritual.
Since leaving a well-lit environment too soon for the darkened woods might lead to undesirable confrontations with tree trunks and branches, Teage informed us about night vision while our eyes adjusted. Human eyes require 20-30 minutes to become accustomed to low light conditions. Coincidentally, it finally gets dark about 30 minutes after the sun first sets. The students oohed appreciatively at the revealed secret of the universe.
I considered Teage’s implication, reflecting on whether twilight length was consistent enough to provide a uniform selective pressure. The period between sunset and full dark (termed “Civil Twilight”) varies with latitude and season, as it reflects the time the sun takes to drop 6° below the horizon. On the same night, civil twilight in Burlington, VT, lasted 9 minutes longer than in Bogota, Colombia, a city near the equator. Atmospheric conditions and local weather can also affect our perception of available light from the setting sun, which increases variability. Pole-to-pole variation aside, the length of civil twilight appears consistent enough at low and middle latitudes to suggest the plausibility of the relationship (though it does not prove it). What mechanisms would select for correctly timed physiological processes? Perhaps some hairy, fanged predator was involved?
Suddenly, I heard Teage ask, “Rachel, do you have anything to add before we head into the woods?”
Bits and pieces of the night hikes I used to lead rushed to mind. Out of the torrent, what would be most relevant to this group of students? Our pupils dilate to accept more light, just like a camera aperture changes size. Our eyes comprise not only lenses (e.g., the cornea) that focus light, but also a receptor structure (the retina), which translates received light into neural signals our brains can understand. The retina, in turn, is made of two types of cells: rods and cones. Rods are far more abundant (about 17 for every cone cell); however, the cones are concentrated in the center of the retina. Responsible for receiving color and fine resolution, cone cells are better suited for working in high-light environments. Rod cells cannot understand color, but they register exceptionally more light than cone cells. The operational ranges of the two cells overlap to some degree; in true twilight, both cells help parse the dim picture before us.
Instead of a long-winded physiology lesson, I settled on a practical and safety-oriented piece of advice. “If you’re having trouble finding the trail in the dark, try using your peripheral vision. Your rod cells—the receptor cells that are really good at picking up light—are arranged on the periphery of your retina, so that part of your eye sees better in low light conditions.” With that, we were off.
As the trail contoured the side of a hill, I followed it with my feet as much as with my eyes. Hard packed dirt spotted with only a few fallen leaves firmly resisted my feet, whereas my wandering steps sunk into noisy leaf litter. After a few quiet minutes, we angled from the trail and picked our way down the gentle slope. Looking out of the bottom of my eyes—as if I wore tiny slivers of half-moon spectacles—proved the best technique for avoiding the tangle of hardy ferns and woody shrubs. Teage motioned for us to stop; this would be our first attempt to call the flying squirrels.
I listened intently. Wind gusted through the upper boughs of white pines and red maples. Still-hanging, papery beech leaves rubbed together, sending bursts of unwarranted excitement running through my mind. Sirens howled close-by. One of Teage’s students fired up the iPod, and high-pitched “chip chip chip” alarm calls radiated into the night to serve as bait. I cupped my hands around my ears to exclude the droning car engines circling the outskirts of the woods. Still nothing. Perhaps the squirrels’ huge eyes, dominated by rod cells, picked us out as we muddled through their habitat.
I relaxed my eyes and marveled at the increased input from my peripheral vision. Intermediate wood ferns stood distinct from the ground; before, they had dissolved into the dimness. It seemed we had been away from bright light long enough for rhodopsin, a photopigment in the rod cells, to build up. Rhodopsin and other photopigments in the cone cells help increase light sensitivity within the receptor cells, though at different rates and degrees. Cone cells, which never develop the light sensitivity attained by rod cells, take only 5-7 minutes. Rod cells, however, may need over 30-45 minutes to achieve full light sensitivity. In the presence of too much light, these photosensitive compounds break down; enough time in dark conditions is thus needed for photopigments to build up to a functional level.
The flying squirrels proved reticent, so we walked through the underbrush back to the trail. The undergrads hesitated less between steps, and they seemed to run into fewer obstacles. After walking a circuit across Centennial Brook and back along the lower slope on the other side, we paused to make their eyes’ night adaption more explicit. Crouched beneath a closed hemlock canopy, we covered our left eyes and stared at the flame of Teage’s lighter with our right ones. I smiled, startled by the pervasiveness of the “Pirate Patch” myth. As lore would have it, pirates did not wear eye patches to cover gaping eye sockets. Instead, they kept one eye in darkness to allow them to see below and above deck without needing time for rhodopsin to develop. While no historical evidence supports this story, the folks at MythBusters put their weight behind its plausibility and likely had a role in its propagation.
Teage flicked off the lighter, and we switched our “eye patch” to the light-blinded eye. Most students commented they could see more precisely with their night-adapted eye than with the light-blinded one. Removing my hand, I winked back and forth at the hemlock boughs above. Sure enough, my left eye discerned individual twigs against the dark sky; my right eye saw only fuzzy dimness. While not proof that Blackbeard covered one eye so he could rush up to a darkened deck from a lamp-lit cabin, our experience supported the possibility.
We emerged from beneath the dense hemlock canopy onto a grassy hillside, where moon-cast shadows danced at our sides. No longer relying on peripheral vision, the students carelessly walked down the trail towards home. I smiled. An hour ago, they had hung together timidly in similar light levels, still uncomfortable with moderate darkness. Now they practically ran. While the flying squirrels had remained elusive, the students found something more powerful: the ability to stride confidently through the night.
by Nancy Olmstead
A month ago I was walking in the woods and it seemed like I couldn’t go more than a few feet without disturbing another chipmunk. The little brown stripe-y streaks were running all over the place, stopping to chirp and chatter at me as I passed. Don’t worry, buddy, I don’t want your nuts.
We’re having a mast year in the northeast. The oaks, beeches, and other masting trees are making a bumper crop of seed, which chipmunks eat and store by the cheekful. This probably explains the superabundance of chipmunks. The eastern chipmunk, Tamias striatus, can tell when the fall harvest is going to be good. So they go all out making babies over the summer. Some of the animals I’m seeing now are probably this year’s offspring, rushing to find, secure, and fill their burrows before settling down for their long winter rest.
Scientists have also studied this phenomenon in red squirrels, and chipmunks may be similar. After all, chipmunks are a kind of squirrel. They belong to the family Sciuridae, the sciurid rodents, which includes chipmunks, ground squirrels (e.g., prairie dogs), marmots (e.g., woodchuck), and tree squirrels (e.g., gray and red squirrels and flying squirrels). Red squirrels are also known to anticipate high seed crops and reproduce accordingly. Females may even have a second litter in the summer that precedes a big fall.
But how do chipmunks and red squirrels know that it’s going to be a good year? The jury is still out on that question. It’s hard to measure what individual animals are using as a cue to guide their reproductive “decisions.” (And by using the word “decisions,” I don’t mean to imply that chipmunks and squirrels have consciousness, just an instinct to reproduce when certain cues are present.)
Scientists involved in these studies have suggested that the visual stimulus of an abundance of flowers may clue the squirrels in, but that explanation is less convincing for chipmunks, who spend more time on the forest floor than up in the tallest trees. Chipmunks may be able to smell the upcoming bounty by homing in on the subtle scent of all those beech, oak, and maple flowers. However they do it, it’s pretty cool.