Thursday, November 16, 2017

Scientists seeking insights into saw-whet owl migration

Nearly every evening between mid-October and Thanksgiving, when the weather conditions are promising for bird migration, Scott Comings sets up a series of nearly-invisible nets on Block Island and plays a recording of the call of the saw-whet owl, the smallest owl to be found in Rhode Island. His aim is to capture as many of the birds as possible, place bands around their legs, and learn what he can about the migratory habits of the diminutive owl.
            Comings, the associate director of the Rhode Island office of The Nature Conservancy, is among a growing cadre of biologists and ornithologists from throughout the coumtry who have been banding saw-whet owls regularly since the early 2000s to get an idea of the bird’s
Saw-whet owl (Megan Lorenz)
movement patterns and population distribution. The effort, dubbed Project OwlNet, began in Pennsylvania in 1997 and now includes several hundred researchers at more than 350 different sites.
            “Before this started, there was a big question about how they move through the area, so it became a concerted effort to see if we could crack this problem,” said Comings, who calls the birds “a really majestic species” despite being just 8 inches tall. “It’s a species that has always captivated me. It’s something you don’t normally see, so that pushes me to want to do more, to learn more, and to go deep into the night trying to catch them instead of sleeping.”
            Peter Paton, professor of natural resources science at the University of Rhode Island, is another of the Project OwlNet collaborators. He has been banding saw-whet owls since 2000 at locations in Richmond, South Kingstown and Hope Valley.
            “It’s as effective to set up the nets at my house as it is at more remote areas,” he said. “It turns out you can put a net out almost anywhere and still do a good job of catching the birds.”
            In a typical year, he catches more than 100 owls, and some nights when the winds are just right, he may catch a dozen or more in just a few hours. Comings catches similar numbers of owls, though one year he banded more than 200 of the birds.
            In the eastern United States, saw-whet owls primarily breed in northern New England and New York and in the Appalachian Mountains, and they winter as far south as North Carolina. According to Rachel Farrell, a member of the Rhode Island Avian Records Committee, saw-whet owls have been documented as breeding in Rhode Island just six times since 1952. Two of those records occurred in the last two years and were documented as part of the Rhode Island Breeding Bird Atlas, which is managed by ornithologist Charles Clarkson.
            “It seems like the species is maintaining a small but persistent breeding population in the state,” Clarkson said.
            But many more saw-whet owls migrate through Rhode Island. Those that are captured by Comings and Paton are revealing interesting details about their migration patterns.
            “We have a much better idea of their migratory pathways,” said Paton. “We’ve also learned that they’re much more common than people used to think. And we see an annual variation in their numbers.”
Paton said that the number of saw-whet owls migrating through the Northeast rises and falls every other year based largely on the number of acorns and other seeds produced by trees in the area. When trees produce large numbers of acorns, they provide abundant food for small mammals like mice and voles, whose populations then skyrocket. When the small mammal numbers increase, saw-whet owl numbers grow, because the owls eat the mammals and can produce more chicks.
Most of the owls caught in Rhode Island fly to the mid-Atlantic states.
“We know that because we’re starting to build a database of where the birds have been caught and where they’ve ended up,” explained Comings. “I’ve had birds I’ve caught recaptured by others in New Jersey, Massachusetts and Maryland, and I caught birds that had previously been banded in Cape May, New Jersey, and Massachusetts.”
Paton has similar records. “One year I caught a bird at my house in Richmond, the next year it was caught in northern Maine, and a week after that it was caught at Audubon’s Eppley refuge in West Kingston.”
One of the more unusual findings from Project OwlNet is that birds migrating for the first time often take a different route than older birds who have previous migration experience. First time migrants tend to be caught along the coast, while adult birds are more likely to follow an inland migratory route.
“The older birds know better when to fly; they’re a little more savvy,” Comings said. “If you’re an adult bird and this isn’t your first rodeo, you know to wait for a northeast wind, which takes you on an inland route. If you’re a young bird, you know you’re supposed to go on a north wind, but if it’s from the northwest it pushes you toward the coast. Almost all the saw-whet owls I catch on Block Island are young ones.”
So far, this year has been a quiet one for saw-whet owl migration. Through the first week of November, Paton had captured only one owl, and Comings hadn’t fared much better.
“It’s been really slow this year because the winds haven’t been right,” Comings said. “But there’s still time. I’m just waiting for that one big night.”

This story first appeared on EcoRI.org on November 16, 2017.

Wednesday, October 25, 2017

Scientists create 'observatory' to monitor climate impacts on Narragansett Bay

            A group of scientists from almost every college and university in Rhode Island is constructing what they call a bay observatory to continuously monitor and model the changes occurring in Narragansett Bay as a result of the warming climate. The system of data-collection devices will include sensors to detect environmental conditions, a “cyto-bot” to photograph micro-organisms, and a way to transmit the data to a publicly-accessible website.
            “We need to improve our ability to measure changes in climate variability and nutrient pollution, in terms of both time and space,” said Geoff Bothun, a professor of chemical
engineering at the University of Rhode Island and a leader of the project. “More accurate measurements at lower detection limits with greater frequency and finer spatial resolution will help dramatically to predict and plan for what is to come.”
            The new instruments will be deployed in Greenwich Bay, in the waters just off the west coast of Conanicut Island, in the bay’s East Passage and elsewhere.  Each will be able to collect data about water temperature, salinity, pH, nutrient levels, dissolved oxygen, currents, and wind speed, while also monitoring biological and biogeochemical activity.
            “We’re trying to understand how various stressors – both human caused and natural – can impact the ecology of Narragansett Bay,” said Lewis Rothstein, a URI oceanography professor. “It’s designed to look at the whole bay ecosystem, highlighting those individual components deemed most important for hypoxia [oxygen deficiency] events, for example.”
One of the unique aspects of the observatory is that it can be programmed to respond to events and trigger a response,” added Bothun. “If we begin to see spikes or trends that are an indicator of an algae bloom, for example, we can trigger our cyto-bot to begin taking more frequent images so we can see the microbiology in the bay at the same time that the measurements are being taken.”
            Although there are already a number of oceanographic measuring devices scattered around Narragansett Bay to collect data for the Rhode Island Department of Environmental Management and scientists at URI’s Graduate School of Oceanography, this new effort requires more precise data that can be fed into computer models to forecast changes that are likely to happen in the near future. So the research team must design and build a new generation of sensors that can more accurately detect minute quantities of various compounds of interest.
            “This is a tough problem, but my vision is to use living biosensors – microorganisms that respond to nutrients and can report to us what’s going on and what molecules are present in the bay,” explained Jeff Morgan, professor of medicine and engineering at Brown University, who leads the sensor development team with URI Chemistry Professor Jason Dwyer. “There are a number of living microorganisms that are terrific at detecting, sensing and reporting the presence of certain nutrients in the environment.”
            Other researchers will approach the sensor development effort from other directions, including nanotechnology solutions, paper-based sensors, and sensors that can be used by citizen scientists.
            All of the data collected by the bay observatory, along with historic data about Narragansett Bay, will eventually be fed into computer models being developed by Rothstein, Baylor Fox-Kemper, associate professor of earth, environmental and planetary sciences at Brown, and others. Their aim is to forecast changes that might occur at a particular place or time so that local decision makers have time to act on those changes.
            “The observatory is in place to do the heavy lifting for us,” Rothstein said, “but we’ll only have instruments at certain spatial points. The modeling is essentially trying to represent what we observed at those locations and interpolate observations at locations where we don’t have instruments. That will allow us to observe the entire bay.
“All of the forecasts will be analyzed and visualized in ways that will provide public and private decision makers with the tools they need to optimize their decisions for the benefit of all Rhode Islanders,” he added.
            The models will also incorporate data from social scientists to factor in the impact of human behavior and how people may behave differently to mitigate particular changes taking place in the bay.
            The researchers will also create an on-line depository they are calling the Rhode Island Center for Data Discovery that will include all of the real-time observational data and modeling data, along with images and historical data.
            “The public will be able to click on a point in Narragansett Bay and take a look in real-time at temperatures or circulation or other ecological variables about that point at a particular time,” Rothstein said. “That will be a legacy program for us.”
            The Bay Observatory is one element funded by a $19 million grant from the National Science Foundation to establish the Rhode Island Consortium for Coastal Ecology,
Assessment, Innovation and Modeling. The grant will be augmented with $3.8 million from the Rhode Island Science and Technology Advisory Council. The collaboration consists of researchers from URI, Brown, Rhode Island School of Design, Rhode Island College, Bryant University, Providence College, Roger Williams University and Salve Regina University.

This article first appeared in EcoRI.org on October 25, 2017.

Saturday, October 21, 2017

That glimmer and glow in the ocean

            That strange glow you sometimes see for a brief moment when you’re standing on the beach at night and staring toward the crashing waves might not be your eyes playing tricks on you after all. It also might not be the moon’s reflection or the flicker of an underwater flashlight or any other explanation you may have come up with. That strange glimmer in the water may be real, and it may have a natural explanation.
            I’ve been curious about the phenomena of bioluminescence – the chemical production of light by living organisms – for many years. In the terrestrial environment, fireflies do it, as do some beetles and a few mushrooms. But in the ocean, numerous creatures can produce light
Bioluminescent plankton in the Maldives (Doug Perrine)
under various circumstances – to lure prey, to attract a mate, or to frighten predators away, among other reasons. In Monterey Bay, California, scientists recently calculated that three-quarters of all marine species are bioluminescent.
In the waters of the Ocean State, bioluminescence is most often seen in the late summer and fall when some types of microscopic plants called dinoflagellates multiply in large numbers. If there are enough of them, these dinoflagellates will glow when disturbed, like when waves crash around them. If you are out boating on the water at night under the right conditions, they also might glow when you jump in the water or start your engine.
Some grape-sized jellyfish called ctenophores and a few kinds of tiny crustaceans also use bioluminescence in local waters.
According to Jim Sullivan, a Providence native and former marine scientist at the University of Rhode Island who is now a professor at Florida Atlantic University, bioluminescence typically occurs when a particular protein and enzyme combine in the body to release photons of light. Creatures typically keep the protein and enzyme separated inside specialized structures in their cells until they are triggered to come together.
“There’s a biochemical control for turning it on and off,” he told me. “In the case of the dinoflagellates, it typically happens when another organism goes to eat them, but they flash as soon as they are touched, and that flash startles the predator, which lets goes of it and runs away.”
The flash of light might also attract a larger predator to come and eat the smaller predator.
A great many questions still remain about bioluminescence, yet few scientists are studying the subject. The U.S. Navy funded most of the research into bioluminescence in the 1980s and 1990s when it believed that modern satellites might be able to detect the movement of submarines by the trail of bioluminescence in their wakes.  Sullivan conducted studies of bioluminescence off Iceland back then when Russian submarines were known to frequent the waters in the area.
Today, the research funding has dried up, but it’s still a fascinating phenomenon to observe.
My only experience with bioluminescence in the ocean was during a midnight walk out to Napatree Point in Westerly several years ago when I was volunteering to monitor breeding horseshoe crabs. During a break in the action, I stared toward the crashing waves and saw what appeared to be a brief blue-green flash of light. It reminded me of a distant flash of lightning or the green flash some say is visible at the moment the sun sets.
Or maybe it was just my eyes playing tricks on me.

This article first appeared in the Newport Daily News on October 21, 2017.

Wednesday, October 11, 2017

The hunt for red October

            Rhode Islanders pay close attention to the changing foliage colors each fall and are justifiably proud of the picture-perfect show the region’s trees put on every year. But Keith Killingbeck, 67, probably pays closer attention than most. A recently retired professor of plant ecology and biology at the University of Rhode Island and the former assistant dean of the URI Graduate School, he has been studying the nutrient dynamics and energy flow in trees – the process that causes the leaves to change color – since his grad school days at the University of North Dakota. A native of Michigan who moved to Rhode Island in 1979, Killingbeck said that despite his 36 years teaching botany, he didn’t start out with a particularly strong interest in plants and foliage. “My passion is for nature and the outdoors and everything and anything that’s part of it.”

Q: Why does New England have the reputation for having the best fall foliage colors?
A: It has to do with the tree species we have and the climate we have. Often in New England we’ll have sunny days and cold nights in the fall, and the tree species that we have respond to
Fall foliage in New England (Glen Russell)
that with a number of chemical changes in their leaves that yield the brilliant colors we see.

Q: What do trees do to produce those colors?
A: One of the most important things they do is break down compounds like chlorophyll to save some of the nutrients, especially nitrogen and phosphorous. Those nutrients are being shunted out of the leaves and moved back into the trees to be saved to be used in the next growing season. It’s essentially a conservation strategy.

Q: Why do different trees exhibit different colors?
A: There’s no easy answer to that. But if we look at birches, they turn yellow. Yellow pigments are unmasked as the green chlorophyll molecules are broken down, and as some of the nutrients are moved out, you have these xanthophylls – accessory pigments in tree leaves -- that show up as bright yellow. Tupelos turn a red-maroonish color, and those are from anthocyanins, a whole different kind of chemical, which are being built up in the fall rather than unmasked. They protect some of the photosynthetic systems in the leaves. It’s complicated.

Q: Do you have a favorite tree for its fall foliage?
A: I’ll give you three. My favorite tree in New England is sugar maple for its peachy color. This is an oddball, but I also like poison sumac, which has this beautiful orange color to its leaves. The third one is Virginia creeper, a vine that has beautiful maroon leaflets in fall.

Q: What factors influence the timing of when leaves change color?
A: The amount of daylight, or photoperiod, is one of the main kickers in all this. Photoperiod is constant from year to year to year, so it’s a good trigger for plants and animals for the timing of anything they do. Within that time period, though, everything from daytime versus nighttime temperatures, precipitation, drought, all those things really impinge on and impact the leaf changing color. The chemistry that’s going on during that time is impacted by all those factors, but photoperiod is a constant predictor of where we are on a year’s cycle.

Q: It doesn’t appear that the leaves all change at the same time. Why not?
A: They certainly don’t. In mid-September, many birches have yellow leaves already, Virginia creeper has maroon leaves already, but most of the leaves on other species are still green – oaks have not turned, most of maples have not turned. Individual species change at different times. In southern Rhode Island, for example, the peak of red maple color is probably around the second or third week in October. Oaks are going to be later, others earlier. It’s species by species and also individual site by individual site. Red maples in very wet areas are going to have their leaves turn earlier than red maples on a much drier site.

Q: How will the gypsy moth defoliation affect the fall foliage?
A: In those areas hardest hit, virtually all the leaves were eaten. Some of those trees that didn’t die reflushed some leaves, but as I’ve looked at some of those trees, the new leaves that were produced after the defoliation were much smaller and there are many fewer of them. So even if those individual leaves turn bright colors, there’s not enough leaf mass to show much color. And, of course, those trees that died, you’ll get no color out of them.

Q: What other factors affect foliage from one year to the next?
A: Ideally, to bring out the most vibrant colors, what works the best is bright sunny days when there is a lot of photosynthesis – they’re producing sugars during photosynthesis – and cool nights for depressing the rates of metabolism so those sugars being produced in daytime are not used up as rapidly as they would be on warm nights. So it’s those sunny days for good photosynthesis and chilly nights. That’s the perfect recipe for vibrant leaves.

Q: Based on those factors, do you have a prediction for what this year’s foliage is going to be like?
A: It’s certainly going to be at the usual time, not knowing what the upcoming weather is going to be, because the variation in timing from year to year is pretty small. I’ve been following leaf color change in individual trees for many years, and the timing changes only by a few days from year to year.  The amount of rain we get, when we get rain, the temperatures at night all make a difference, but it’s very subtle. This year the thing that’s going to impact our color most is whether trees were defoliated in spring and early summer. But other than pockets of trees that were defoliated, I think the colors are going to be great again this year.

Q: Why do some individual trees change color especially early, like in August?
A: I’ve observed that also, and in fact I have a single red maple tree that I call my early red maple that I see when I drive to campus every day. It turns earlier than any of the other red maples around it. I think it’s genetics. The genetic makeup of the individual. The environmental conditions are the same versus trees meters away – whether it be soil conditions, rainfall, sunlight, anything else – so the difference has to be attributed to genetics.

Q: Is climate change likely to have an effect on foliage colors or timing in the coming years?
A: The simple answer is yes, as far as we can tell. There are certainly phenological studies around the world that show plants budding earlier in the spring than normal, extending the growing season on the front end, and it appears that leaves are being held onto later in the fall, at least for some species, extending the growing season on the tail end. So it certainly seems that the warming of the planet is having an effect and will continue to have an effect.

This article first appeared in the Newport Mercury on October 11, 2017.

Sunday, October 8, 2017

Wildlife rehabilitators in Rhode Island

            At the end of a quiet dead-end street in Westerly, a three-story brick house is surrounded by a maze of shed-like structures that seem only slightly out of place. The largest is 40-feet long and 12-feet tall and sheathed almost entirely in wire screening. Inside, laying on a tree stump, is the carcass of a half-eaten squirrel. And perched on a beam above the carcass are two female red-tailed hawks – Griffin, a 7-year-old with a deformed beak, and Matrix, 15, who has a traumatic head injury from being struck by a golf ball at a country club in Massachusetts.
The two birds periodically fly the length of the cage to exercise their wings, then swoop
Baby cottontails (James Jones)
down to peck at the squirrel carcass. Every year, one of them lays an infertile egg, and the birds take turns incubating it until they realize it’s not going to hatch.
            Adjacent to the flight cage are a dozen 8-by-10-foot cages. In one sits a turkey vulture named Lurch with neurological damage caused by ingesting something poisonous at the Charlestown landfill. Next door is Krypto, a peregrine falcon born on the Superman building in Providence but who flew into a window of the downtown Blue Cross Blue Shield building, breaking its wrist and causing a head injury. Nearby, two barred owls perch in a darkened section of their cage, one-eyed Wink and his partner Boytoy, who was rescued after being struck by a car.
            The newest cage, built last year with the help of a local eagle scout, houses a red-tailed hawk that struck a window so hard that the homeowner thought it was a gunshot.
“It was paralyzed for 11 days, but on the 12th day we arrived to see it standing up, and it’s slowly getting better,” says Vivian Maxson, who operates the Born to be Wild Nature Center with her husband John. “It now can fly the length of the cage, and we’re hopeful it can be released.”
            Most of the birds at the nature center have permanent injuries and would not survive in the wild, but some are destined to be returned to the outdoors when they heal.
            The Maxson’s started Born to be Wild after taking a wildlife rehabilitation class through the Rhode Island Department of Environmental Management and apprenticing with a certified rehabilitator.
“That person starts you off with easy cases, like baby squirrels or opossums, then you get bumped up to the next level and you’re on your own,” Vivian says. “I really like the feeling of giving back to nature. Man’s impact causes so much harm that it’s a way to try to balance it out.”
            “All it takes is one or two enjoyable cases, and it strengthens us and keeps us going,” adds John.
            The Maxsons have become the state experts at rehabilitating raptors, so almost every hawk or owl in Rhode Island that is found injured or unable to care for itself usually finds its way to their nature center. Every day, they provide the birds with their preferred meal – dead mice and rats for some, squirrels and rabbits for others – and assess the health of each to determine when they are ready for release. When they have time, the Maxsons also host tours of the nature center or bring some of the birds to summer camps and retirement homes for educational programs.
            About 70 hawks and owls spend time at Born to be Wild each year, and about 65 percent survive to be released, a better success rate than the national average. Some must be euthanized because of the seriousness of their injuries.
            According to John, the most difficult hawks to care for are ospreys.
            “They only eat live fish, so every day I have to go fishing,” he says with a smile. “Anyone who visits us in the summer, we hand them a fishing pole and tell them to go catch some fish.”

....Continued in the October 2017 issue of Rhode Island Monthly magazine.

Friday, October 6, 2017

Hidden world of Narragansett Bay on the rebound

            When imagining the places on Earth with the highest diversity of species, most people think about the Amazonian rainforests or the jungles of Southeast Asia or the plains of Africa. Seldom are marine habitats even considered. And when they are, it’s coral reefs that get most of the attention.
            But biologist Steve Hale said that two-thirds of all of the animals on the planet live on or in seafloor sediments or what scientists call the benthic environment. And when only calculating the marine species, about 98 percent live in the sediments.
            A research ecologist with the U.S. Environmental Protection Agency in Narragansett for the last 20 years, Hale recently finished compiling a master list of all the species ever recorded in the sediments of Narragansett Bay. He discussed the project in a lecture at the Rhode Island Natural History Survey on September 28.
The list includes 1,056 species, and he believes there may be another 200 to 300 still to
be found. Most live in the top 10 centimeters of the sediments. The most abundant creatures recorded are varieties of polychaete worms, mollusks and arthropods.
“But rare species make up most of the biodiversity,” Hale said. “Included are 395 singletons – species found only once – and 224 doubletons. Another 279 were captured prior to 1950 and have not been seen again” due to range shifts, pollution, the effects of invasive species and other factors.
            Based on his analysis, Hale said that the biodiversity of benthic organisms in Narragansett Bay declined from the 1880s to the 1980s due to pollution produced during the Industrial Revolution, raw sewage, heavy metals and other toxins released into the bay. The filling in of salt marshes, the disappearance of eelgrass beds, and other habitat destruction also caused a decline in benthic diversity.
            But as the bay was cleaned up in the later years of the 20th century, benthic biodiversity experienced a partial recovery, though it has not yet achieved pre-industrial levels and may never do so.
            To compile his master species list for Narragansett Bay, Hale scoured every bit of historical data he could find. Most came from online databases maintained by the Smithsonian Museum of Natural History, the Harvard Museum of Comparative Zoology, and the Yale Peabody Museum of Natural History. 
But he also uncovered reports of species collected by professional and amateur naturalists as far back as 1834, when the chief engineer for the construction of Newport’s Fort Adams, Joseph Totten, took samples from the bottom of Narragansett Bay and published a report of his findings.
In the succeeding decades, notable scientists visited the area and contributed data, including Alexander Agassiz, who established the Newport Marine Zoological Laboratory at Castle Hill in 1873 and was dubbed the first oceanographer of Narragansett Bay, and Addison Verrill from Yale University, the first to use a steamship to collect benthic samples in the bay.
The 99 different studies that Hale compiled represents surveys of 200 different sites around the bay.
“Only about 600 square meters of sediment has been sampled,” Hale said, noting that it represents about 0.000002 percent of the bay’s area. “But we still think about 80 percent of all the species have been found.”
Benthic creatures perform vital ecosystem services, according to Hale. They filter the water, sequester carbon, process waste, recycle nutrients, provide food for birds and commercial and recreational fisheries, and provide nursery habitat for other marine organisms.
Although Narragansett Bay seafloor communities have rebounded as the bay has become cleaner, Hale said they must still deal with numerous unhealthy stressors, from storm water run-off and toxins in the sediments to invasive species and low dissolved oxygen levels.
“When we have our seasonal hypoxia [low oxygen] events in the upper bay, our rare species get hammered,” said Hale. “They’re very sensitive to disturbances and susceptible to local extinctions.”
Increasing water temperatures from climate change will likely lead to changes in the range of some species, which will alter the composition of the species in the bay.
Will the benthic communities of Narragansett Bay continue their recovery? Hale said it’s hard to say.
“We’ve made a lot of progress by putting a lot of money into improving our sewage treatment plants,” he said, “but non-point sources of pollution are still a problem. Mix that with invasive species and warming waters, and it’s hard to say how things are going to go. I don’t have a good answer to that, but I’m hopefully optimistic.

This article first appeared in EcoRI.org on October 4, 2017.

Wednesday, September 27, 2017

New technology revealing details of bat migration

            The Pettersson D500X ultrasound recorder looks a bit like an old-fashioned transistor radio with square buttons, a modest display screen, and a built-in microphone. Yet despite its unimaginative appearance, the device can detect the echolocation sounds made by bats and, with the help of software that identifies the bat species involved, is helping scientists reveal new information about the movements and migration behavior of local bat populations.
            Biologists at the Rhode Island Department of Environmental Management and the University of Rhode Island have deployed the bat detectors throughout the state this year in a variety of ways. DEM wildlife biologist Charles Brown, for instance, mounts one on the roof of his truck as he periodically drives five routes around the state to look for trends in bat numbers and to compare his findings with those driving similar routes in other states. He also places the
Silver-haired bat (The Nature Conservancy)
devices in various state wildlife management areas to scout for locations to trap bats for more detailed studies.
            The most revealing use of the detectors, however, has been as a way of monitoring bat migration through the state.
            “Not a lot is known about bat migration, so we’re just trying to figure it out for various reasons,” said Brown. “There’s a great interest in wind turbine development – turbines kill hundreds of thousands of bats every year – so we want to know when they migrate and where.”
            Brown selected several locations along the Rhode Island coast to place the detectors for long-term monitoring of bat movements. Every week since early August, he has downloaded the data from the detectors to learn what he can about the seasonal movement of bats.
            “Much like birds, they migrate at the same times and during the same general weather patterns,” Brown said. “They head south until they hit the coast and then they follow the coastline. There are certain locations where you’d expect them to pile up and be concentrated, like Point Judith, Sakonnet Point, Beavertail, Brenton Point.”
            While he admits he didn’t know what to expect with the data he was collecting, he was somewhat surprised to learn that bat migration appears to begin much earlier than he anticipated.
            “We’re seeing pulses of activity beginning in August, and I’m not sure that’s well known,” Brown said. “But they’re opportunistic animals, so when they get the right weather conditions, they probably just figure that this is a good time to go.”
            Bat migration is believed to continue through October and early November.
            The only difficulty with the bat detectors is that it’s impossible to know how many bats are being detected.
            “It might detect a thousand calls in one night, but we don’t know if it’s a thousand bats flying by or one bat that flew by a thousand times,” he said. “There’s no way to differentiate it.”
            Most of the bats Brown has detected are red, hoary and silver-haired bats – collectively called tree bats – all of which migrate south each fall. He also occasionally detects small numbers of little brown bats that migrate north to hibernate in caves and mines in New Hampshire and Vermont. Little browns have declined dramatically in the last decade due to the effects of white-nose syndrome, a fungal disease that has killed millions of hibernating bats throughout the Northeast. Big brown bats, many of which spend the winter hibernating in Rhode Island, are also detected.
            URI Professor Peter August has conducted similar monitoring of bat migration at Napatree Point in Westerly using the same kind of detector, and his results mirror Brown’s.
“While in mid-summer I’d have a couple hundred bats passing by in a week, starting in August I’ve been getting a couple thousand in a week. The activity has really peaked.”
            He plans to continue to monitor for bat activity at Napatree until he detects no bats at all.
            “Nothing brings great clouds of bats to Napatree in the summer, which is what I expected,” said August, who earned his doctorate studying bats in South America. “It’s not an active summertime habitat, but it changes this time of year. We have lots of bats moving around now. Our migratory bats are headed south, and our hibernating bats are moving around the area looking for places to hibernate.
            By combining data from the detectors with anecdotal information from other sources – like surfers who report large movements of bats at sunrise and wind turbine owners who report dead bats at the base of the structures – Brown and August are piecing together the story of bat migration in Rhode Island.
            “With all this information, we’re finally getting a better sense of what’s going on here,” Brown said. “The information we’re getting will give us a better sense of how big a problem wind towers will be for our bats. As more and more wind turbines pop up on the landscape, it’s probably going to be a problem. It’s already a problem. And then we’ll have to question whether the mortality is sustainable.” 

This article first appeared on EcoRI.org on September 27, 2017.