Migration takes guts

            The impressive coordinated migrations of wildlife like monarch butterflies and salmon have always made me curious. How do they know where they’re going, when to start, what route to take, and when they have arrived at their destination? Those are questions I think about every spring, too, as millions of birds migrate to our area, many traveling great distances under treacherous conditions. And some of them still have a long way to go once they get here.

            The tiny blackpoll warbler, for instance, undertakes a two- or three-day flight across open water each autumn from southern New England to the Caribbean with nowhere to land if it gets

tired. And the even tinier ruby-throated hummingbird crosses the entire Gulf of Mexico in 24 hours without stopping, their buzzing wings flapping at about 50 beats per second the whole way.

But how are they able to keep going for so long without refueling?

The answer, according to Scott McWilliams, has everything to do with the digestive physiology of the birds. Or, as the University of Rhode Island ornithologist likes to say, “migration takes guts.”

McWilliams studies the physiology of migrating birds. He captures migrant yellow-rumped warblers, hermit thrushes, white-throated sparrows and other species on Block Island or at the Kingston Wildlife Research Station near URI. For most of the birds, Rhode Island is only a rest stop at the halfway point of their seasonal migration. He then evaluates the physical condition of the birds, the food they eat and other factors – sometimes conducting short dietary experiments with them before releasing them again – all to understand the physiological changes that take place when the birds migrate.

What he has found continues to astound me every time I think about it.

The URI professor says it takes a great deal more than an innate knowledge of what route to travel and strong flight muscles to successfully complete their twice-a-year migration. It takes a digestive system that is highly adaptable to different activities and conditions, what scientists call phenotypic plasticity. This physiological flexibility enables some species to double their weight, support long-distance flight, and withstand changing temperatures.

            In the days preceding migration, songbirds increase the size of their gut by producing new and larger cells. This makes it possible for the birds to dramatically increase how much food they can consume so they can store up extra energy.

            The digestive system, however, uses massive amounts of energy to operate. So once the birds have packed on the calories, they can shut down their digestive tract so the energy that would have been used to process food can be diverted to fuel flight. 

McWilliams said that the birds’ guts actually begin to atrophy during migration. Unfortunately, that means that when the birds stop along their migratory route or reach their ultimate destination – a time when they are surely hankering for a meal – they are unable to eat for a day or two until their gut resumes operating normally again.

            This discovery explains why birds do not immediately gain weight when they complete their migration. It also provides insight into their dietary requirements prior to departing. Because rather than exclusively consuming high energy foods to sustain their flight, they also must eat proteins to help rebuild their digestive tract at the end of the trip.

            Which reminds me that I should probably go for a bike ride. It’s not only birds that can modify their bodies to accomplish formidable feats of endurance. With a little exercise, people can too.

This article first appeared in the Independent on April 20, 2017.

Marine debris a growing problem for beaches, wildlife

            Geoff Dennis walks the Little Compton coastline with his black lab Koda almost every day, and he is disgusted by the quantity of trash that accumulates on the beaches. So every day he picks up every bit of it he can find, and he records how many of each item he collects. He even saves much of it so he can document the annual accumulation with a photograph. He said the problem seems to be getting worse.

            Last year he picked up 2,380 plastic bottles, 1,330 mylar balloons and 395 drinking straws, for instance.

            A quahogger for 30 years, Dennis said he “got a taste for trash” while monitoring piping

Geoff Dennis's dog Koda sits next to 2,380 plastic bottles
collected from Little Compton beaches.

 plovers at GoosewingBeach for The Nature Conservancy about a decade ago.

            “It really bothers me. The first time I walked with the dog, I came back with over 100 mylar balloons,” he said. “If I can start a conversation with people about it, that’s great. But most people just don’t care.”

            Dennis estimates that about half of the trash he finds was dropped recently by people using the beaches, while the other half drifted in on ocean currents and could have come from anywhere. He sometimes finds items covered in gooseneck barnacles, a species not found locally that Dennis said probably drifted north on the Gulf Stream.

            “Over a typical year, the largest volume of stuff I pick up is commercial fishing gear,” he

Koda poses with a year's worth of Mylar balloons.

said. “You get huge pieces of netting all over the place, little pieces of green twine, pieces of tires they use on the draggers.”

            The problem of marine debris and beach trash is overwhelming. According to a new documentary, A Plastic Ocean, about 8 million tons of plastic are dumped into the ocean every year. Much of it is still out there just waiting to be consumed by fish, sea turtles, albatrosses and other marine creatures. The plastic that isn’t consumed by wildlife eventually washes up on a beach somewhere.

July Lewis, who coordinates beach cleanups throughout the state for Save the Bay, said there are two aspects to the issue of marine debris – aesthetics and wildlife impacts.

            “No one wants to come to a beach that’s covered in trash,” she said. “It makes a difference in how people can enjoy our beaches.”

            From a wildlife perspective, however, it can be a life-or-death issue. Sea turtles consume plastic bags and latex balloons that they mistake for jellyfish; whales that feed on large quantities of plankton cannot separate out the microplastics from the edible microorganisms; and tiny bits of plastic get caught in the gills of fish. One 90-day old albatross chick was found with 270 pieces of plastic in its belly.

            “Even if it’s not fatal, it’s a burden on these animals,” said Lewis. “It’s hard to calculate exactly what that burden is and what the mortality may be from it, but it’s increasing because we know that the amount of plastics in our ocean is increasing every day. Most everything that lives in the ocean has some plastic in them.”

            Lewis said that monofilament fishing line is especially dangerous to marine life because they can easily become entangled in it. “It’s meant to be invisible and unbreakable, so it’s a serious entanglement hazard to marine life,” she said.

Nearly 1,500 pieces of fishing line at least a yard long were picked up on Rhode Island beaches last September as part of the International Coastal Cleanup. In addition, Lewis said that the event’s 2,205 volunteers also removed about 46,000 cigarette butts, 7,500 plastic bottles, 4,800 glass bottles, 13,000 pieces of plastic, 10,500 food wrappers and 5,700 plastic bags from 65 miles of Ocean State shoreline.

            Dave McLaughlin, executive director of Clean Ocean Access, a Middletown-based non-profit group that organizes dozens of beach cleanups on Aquidneck Island every year, said that the problem of plastics in the ocean continues to increase. “By 2050 there will be more plastic in the ocean than fish,” he said. “That’s a pretty scary statistic.”

            In the last 10 years, his group has removed nearly 95,000 pounds of debris from Aquidneck Island beaches. “We’re still finding debris left on the shoreline from the storm surge of Hurricane Bob and Hurricane Sandy, some of which has been out there for 20 years,” he said.

            Clean Ocean Access has adopted a unique technology used at marinas on the West Coast to help address the problem. The group installed a trash skimmer in Newport Harbor that uses a dumpster-sized contraption with a motorized pump to suck floating debris – as well as oil and other pollutants – into the container for disposal. Between August and December of last year, it collected more than 6,000 pounds of debris. McLaughlin aims to install four more at other marinas around the state next year.

            “It’s like watching paint dry,” he admitted. “It looks like it’s doing nothing, but when you come back eight hours later, it’s collected a lot of stuff.”

            With Earth Day approaching, McLaughlin and Lewis encourage Rhode Islanders to join in some of the many beach cleanups taking place this month around the state. Save the Bay-sponsored cleanups can be found here, or join Clean Ocean Access at a cleanup of the Cliff Walk on April 22 from 10 a.m. to noon.

            Clean Ocean Access is also sponsoring a screening of the film A Plastic
Ocean at the Jane Pickens Theater in Newport on April 26 at 6:30 p.m.

            “In the grand scheme of things, picking up someone else’s trash on the beach isn’t changing people’s habits,” said Geoff Dennis. “But in my little niche, it’s making a difference.”

This story first appeared on EcoRI.org on April 14, 2017.

Radar data proves Rhode Island's importance to migrating birds

            Rhode Island is a small state, but it plays an outsized role in providing food and habitat for migrating birds traveling through the region each fall.

That’s the preliminary result of the first year of data collected for the Rhode Island Bird Migration Atlas, which combines satellite data of mass movements of birds during migration with field observations collected along 10 transects scattered throughout the state.

“We’ve confirmed what we’ve always suspected – Rhode Island is a very important stopover site for migrants. We’ve just never been able to put numbers to it before,” said Charles

Clarkson, the ornithologist who leads the project on behalf of the University of Rhode Island and the Rhode Island Department of Environmental Management.

Clarkson said that the bulk of the birds migrating north along the Atlantic flyway in the spring travel to the west of Rhode Island, whereas most of those traveling south each autumn do so by crossing through the state.

“It seems like there is a funneling effect, with large numbers of birds heading south and avoiding going over open ocean,” said Clarkson. “They’re not heading toward the beaches in eastern Massachusetts but are instead hooking west, passing through Rhode Island and along coastal Connecticut and New York before turning south along the New Jersey coast. They all seem to funnel through our state on a southwest trajectory.”

Among the other findings noted so far is the discovery that Rhode Island has what Clarkson called a very protracted migration.

“We have just one year of data, but it seems that one of our busiest migratory nights was the last night of data collection,” Clarkson said. “We had huge pulses of birds moving through the state early and much later in the migratory season, suggestive of a much more protracted migratory season in Rhode Island than you might expect.”

No other state in the country has attempted to map and quantify the migratory movements of birds. Clarkson said that Rhode Island’s small size makes the project more feasible than in larger states.

Clarkson spent three days in March at the AeroEcology Laboratory at the University of Delaware, which uses weather radar to analyze migratory bird movements.

He said that weather radar “shoots a laser beam” into the sky, which bounces off an object and creates an image. The beam can also determine how quickly objects are moving in the sky, which enables scientists to differentiate between, say, wind-borne leaves and birds.

“You can use these two metrics to get an idea of when, how quickly and how many birds are moving through an area,” he said. “When we looked at the data for Rhode Island, we saw that Rhode Island is used very heavily during fall migration relative to neighboring areas. Rhode Island seems like a hotbed of fall migratory movement by birds.”

            The radar data was combined with data collected by two researchers regularly walking 10 transects during the migratory season. They recorded every bird they saw and heard, as well as data about insect abundance as a measure of food availability. This on-the-ground data provided what Clarkson referred to as “bird use days,” or the number of days during the migration period that birds used each site.

            “That gives us an idea of how long birds hang out at these spots,” he said. “And the insect counts give us an idea of what fuel source is available to them as they hang out. It also gives us an idea of turnover. If we see 50 robins one day and two days later we see 50 robins and two days later we see no robins, that gives us an idea of how long that flock hung out and refueled before they picked up and moved on.”

            While the data has not yet identified particular species that use Rhode Island habitats more than others, Clarkson said the state appears to be an especially important stopover location for songbirds that breed north of the state and winter in the Tropics, including blackpoll, magnolia and black-throated blue warblers.

            “We had plenty of the standard stuff, too – flocks of hundreds of robins, huge flocks of grackles moving through,” he said. “And almost always in those monospecific flocks you’d see Cooper’s hawks following them everywhere they went. Inevitably we’d be able to predict when we’d see birds of prey based on those monospecific flocks moving through.”

            The migration atlas project will continue collecting data for two more years, increasing the number of transects studied from 10 last year to 50 this year.

This article was first published on EcoRI.org on April 5, 2017.