Weir’d Wildlife Jobs: A Summer at Hubbard Brook Experimental Forest

Larval Northern Spring Salamander

I slide what appears to be the remains of a frog between my thumb and index finger, searching for any marking that might hint at the identity of its former owner.  The egg-shell white skin is cool and smooth like ceramic and tears as easily as wet tissue paper.  It is not sticky, nor is it exactly slimy.  A pale, but distinctly yellow tinge along its edge informs me that this skin came from the rear legs of a Pickerel Frog.  I jot down my findings and gently toss the integuments onto the grassy berm before picking up the next pile of entrails a few inches away.  I don’t need to look long to know this is the back of an American Toad.  The bumpy skin is a dead giveaway, and a distinct sharp stench, like something between motor oil and pine sap, stings my nostrils as I peel the flattened body from the asphalt.  Toads don’t smell that way in life.  Just freshly dead.

This might all sound a bit grotesque, but when it's your job to tally and identify all the roadkill amphibian species after every weather event, it gets to be pretty second nature.  As a field biologist, I have amassed quite the array of inexplicably specific skills, that, as far as I can tell, have no “real world” analogue.  If I’m not out on a rainy weekday night, identifying amphibian guts on a busy on-ramp, I’m out following turtles with little radio antenna backpacks up and down thorny hillsides in 95-degree heat.  I’ve floated on my belly (donned in a full wet-suit, snorkel and all), in just over a foot of water, reaching my bite-size fingers into the dark, algae-encrusted crevices between rock slabs.  I’ve counted, measured, and cataloged thousands of random bits of my surroundings from the amount of salts in the soil, to the percentage of moisture in the air.  I’ve tallied rocks of a specific size, estimated how much sunshine is blocked by the leaves, and spun myself in circles trying to head exactly 144 degrees.

Adult Northern Spring Salamander

Learning to do field work is like training for some bizarre form of the Olympics.  It’s not just about getting faster at identifying all the mosses in a square meter frame, it’s about getting more precise and more consistent with your teammates—fellow field techs and grad students.  By the end of the field season, measuring half a dozen transects along a stream bank is so intuitive that I almost crave the opportunity to put my skills to the test in some sort of field contest.  When else in life will I have to perform minor surgery on two dozen five-inch salamanders in an afternoon, or devise a way to clip the toenails from a box turtle that is clamped tightly in its shell?

Most of my stories recounting splattered frog legs, catching snot otters, or sexing snapping turtles are met with a mix of tentative curiosity or masked repulsion from the non-wildlife oriented.  By their very nature, wildlife jobs take place off the radar of most people.  There is always the odd run in with the nearby snake-poaching property owner, or the group of campers tromping through your study site, but for better or worse, most don’t seem to know the field exists.  I’m used to the blank expressions when I declare I study reptiles and amphibians.  The classic, “what can you do with that,” is the usual retort.  Some seem to imagine that a career in wildlife means you get to play with cute and fuzzy animals all day, and while that is sometimes true (minus the fuzzy in my case) there is a lot more to jobs in wildlife and ecology than one might expect.

A wood frog found at Hubbard Brook Experimental Forest

The Hubbard Brook Experimental Forest is an epicenter for weird wildlife jobs.  I used to consider field work somewhere in the hazy divide between vacation and exile.  Once the routine kicks in, weeks and months can easily fly bye without so much as an email from our principle investigator.  Any semblance of a social life is put on relative hold as we race to collect enough data before the weather turns.  It’s tons of fun but can be pretty isolating at times. 

Hubbard Brook is something else entirely.  Imagine a neighborhood with a half dozen buildings and a large lake for a backyard.  Every morning, instead of driving to the office dressed in a suit and tie, brief case in hand, everyone here walks out the front door clad in muddy hiking boots and polyester pants, the day’s equipment tucked under each arm, and heads for the woods.  There are crews studying soils, trees, birds, water, vegetation, amphibians, you name it.  Potlucks and science talks are held every week.  During two days in July, researchers, professors, land managers, graduate students, and undergrads travel from all over the country and the world to take part in ‘The Meetings,’ a conference discussing current research and the state of the forest.  I’ve never been anywhere that felt like such a hub for environmental science.  

Northern Dusky Salamander.

What makes Hubbard Brook such a research Mecca, are the long-term, large-scale experiments that have been ongoing here since the 60s.  Located in Central New Hampshire in the southern part of the White Mountains, this 7,800 acre valley has entire watersheds devoted to answering specific questions regarding natural and human disturbances.  In the 1960s, 70s, and 80s, several watersheds were systematically deforested to varying degrees to determine the effects on forest regeneration, stream flow, and nutrient cycling.  In 1999, another watershed had 45 tons of calcium dropped by helicopter to offset the effects of acid rain.  Other, large scale experiments have included artificial ice storms, climate change monitoring, and impacts of disease and invasive species on plant and animal communities.  The remaining water sheds have been left as controls and are intensively monitored for comparison with these landscape-scale test tubes. 

Northern Two-lined Salamander.

I was hired as an REU (Research Experience for Undergraduates) student for a project working with stream salamanders at Hubbard Brook.  Upon arrival at our field house, I was baffled to find the walls decorated by half a dozen photographs of what appeared to be outhouses.  Much to my embarrassment, it was soon made clear that these were not toilets, conveniently positioned at the top of each of our field sites, but weirs.  The ‘gage house,’ which I had mistaken for a latrine, contains a complex system of pulleys and measuring equipment used to record changes in water flow over time.  Like something out of a disaster movie, a hydrograph scratches a series of jagged lines onto a sheet of paper fed slowly through the machine as the water level rises and falls. 

Northern Spring Salamander.

While often used to describe the entire apparatus, the ‘weir’ itself actually refers to the V-notch, a V-shaped cut in the front of a large, rectangular collecting pool or ‘ponding basin’ over which water pours back into the stream.  Thanks to the design of the V-notch, the height of the water in the ponding basin translates to the amount of liquid flowing out of the watershed.  Occasionally, high flow events overtake the level of the V-notch, rendering its measurements useless.  A backup ‘flume’ which sits behind the ponding basin, is used in these cases.  It also records the flow rate, but to a less accurate degree. 

There are nine weirs in the Hubbard Brook valley, each measuring the flow of a different stream.  Thanks to the long-term data these weirs collect, scientists can test hypotheses regarding differences in stream flow rate as well as monitor water levels on an hourly basis.  Stream flashiness is of particular interest to wildlife biologists studying stream dwelling organisms.  A “flashy” stream swells rapidly during a storm before dropping back to baseline levels just hours after the precipitation has passed.  This rapid influx of water can modify habitats by overturning rocky substrate and woody debris, influencing survival of everything from macroinvertebrates to fish and amphibians. 

A large Northern Spring Salamander.

Dr. Winsor Lowe of the University of Montana has been collecting data on spring salamanders in New Hampshire for decades.  He has revealed some fascinating patterns related to their movements and dispersal, but one recent finding suggests a decline in adult salamander numbers over the past few years.  It has been hypothesized that increased stream flashiness could be to blame.  Two of his students, Maddy Cochrane and Leah Swartz, are hoping to shed some light on this mystery.

Maddy is a first year PhD student with short, brown hair, a can-do attitude, and a keen sense of adventure—she once told me about a personal bet to try every rope swing she sees.  Maddy conducted her Master’s research on wood turtles in Minnesota and is now using the closely studied hydrology of Hubbard Brook as a proxy for the impacts of climate change.  Leah Swartz did her Master's with Dr. Lowe and is now manager of his lab.  She has a tall, runner’s physique and a strict attention to detail.  Leah is helping me craft my own independent project (one of the perks of being an REU student) looking at the impacts of fish predation on salamander stress levels. 

A larval Northern Spring Salamander.

While I recuperate on the couch after a “short” eight-hour day in the field, Maddy and Leah typically head out for an afternoon run and swim, or the occasional rock-climbing session.  How they find the time and energy, I don’t know.  These two are more like ultimate rocky mountain tour guides than any biologist I’ve ever met.

With the help of telemetry, Maddy, is getting to know the day-to-day lives of spring salamanders better than just about any other scientist.  After inserting 12-millimeter PIT tags beneath the skin of three dozen spring and dusky salamanders, she has been able to record their fine scale movements and habitat preferences.  A telemetry wand, reminiscent of a metal detector, can locate these PIT tags from as much as 30 centimeters away as it is waved over the rocky substrate of the stream bed.  This is only her first year of data collection, but hopefully these intimate observations will help us understand what environmental factors contribute to reduced survival in salamanders.

A larval Northern Spring Salamander.

Before we can collect any of this data, however, we must catch the secretive salamanders.  For the first three to five years of life, northern spring salamanders are fully aquatic.  During this life stage they are called larvae, and have feathery, external gills, fish-like eyes, and a large, paddle-shaped tail.  Unlike a frog and its tadpole, these larval salamanders have two skinny pairs of legs, making them more closely resemble the adults.  Once a larva goes through metamorphosis, it absorbs its external gills, changes from a silvery gray to a dark, mottled orange, and begins to forage on land.  As basal members of the family Plethodontidae, adult spring salamanders lack lungs and respire through their permeable skin.  Unlike some of their more derived relatives, the genus Gyrinophilus is strongly tied to the water, and adults can commonly be found under rocks along stream margins or even submerged in the main channel, or thalweg. 

Leah Swartz with Tupperware full of salamanders.

Leah is adding to Dr. Lowe’s long-term mark/recapture data set by conducting 500-meter-long surveys in each of six stream reaches.  By the end of this summer, we will have conducted 54 of these surveys, flipped 27,000 rocks, and caught just shy of 1,000 salamanders.  A good day’s haul can land us with nearly 50 salamanders to process, though a few reaches consistently (and frustratingly) turn up five or less per day. 

We begin each survey staggered along the stream every 100 meters, armed with zip-lock bags, pockets full of flagging, and a tally counter.  I move along slowly, hopping from one granite boulder to the next, flipping large, rounded rocks every meter.  Two hands are essential to keep these rounded stones from spinning in their sockets and crushing anything that might be lurking below.  Any rock, no matter how inconveniently positioned, could hide a salamander.  I grip the rough, almost sharp, texture of one particularly good-looking rock, and gently lift it out of the water.  An elongate, silvery body wriggles nervously in the clear, gently flowing current.  With one hand, I cut off the salamander’s escape and usher it gently towards my open plastic bag held flush with the stream bed.  The salamander darts to one side of my trap, then to the other.  After a few moments of finessing with the stubborn amphibian, it enters the bag just far enough for me to scoop it out of the water.  I mark its rock with a piece of flagging and record the meter location and habitat. 

Inserting a PIT tag into an adult Northern Spring Salamander.

Each salamander we catch goes through the same rigorous processing.  First, I scan each salamander for a PIT tag, noting any recaptures.  New salamanders are sedated using an anesthetic called MS-222.  Once asleep, I can easily make a small, painless incision in the salamander’s flanks.  The cut is just deep enough to break the skin; they don’t even bleed.  A PIT tag is then inserted under the skin using a syringe.  Prior to the use of PIT tags, researchers injected salamanders with elastomer.  This is essentially a coded tattoo that fluoresces under a black light.  If we can catch our marked salamanders again in subsequent surveys they can help us understand population size and survival probability.

We record weight, snout-vent length, sex, and note tail condition before snipping off a small piece to be preserved for DNA analysis.  This is of little consequence to the salamander, as they can regrow the tail in a few months’ time.  After processing, we allow each salamander time to recover in a fresh water bath before returning them to the very same rock where they were found.  The whole affair takes just a few minutes for the sallies, but catching and processing 50 salamanders can take us all day. 

Northern Spring Salamander in Stream Habitat.

As of today, we have just ten mark/recapture surveys remaining before we head back to our respective universities.  I have added to my repertoire of weird wildlife skills and, for the first time in my undergraduate career, I have had the opportunity to ask my own research questions and conduct my own experiments.  We are currently in the process of collecting corticosterone samples in four of our stream reaches to compare salamander stress levels with and without predation from fish.  I still have much to learn as I begin the daunting tasks of writing up our results while simultaneously entering my final year at Ohio University, but I feel more prepared for the future of my academic career than ever.  Maddy and Leah have been great friends and mentors this summer, and who knows, maybe I will even end up doing a grad project in their lab.  

These past four months at Hubbard Brook have helped me grow immensely as a young scientist.  I will miss waking up to the mournful calls of loons each morning and looking for moose in the evenings.  Hubbard Brook has been pumping out science and scientists alike for decades and I feel proud to be a part of that legacy if only in a small way. 

I know I will have to return to this amazing community of researchers and field technicians soon.

Thanks for reading!
Keep living the field life
RBW