Popular pet turtles outcompete native species when released

            They’re the most popular pet turtle in the United States and available at pet shops around the world, but because red-eared sliders live for about 30 years, they are often released where they don’t belong after pet owners tire of them. As a result, they are considered one of the world’s 100 most invasive species by the International Union for the Conservation of Nature.

            And southern New England isn’t immune to the problems they cause.

            “I hear the same story again and again,” said herpetologist Scott Buchanan, a wildlife

Red-eared slider (left) and smaller native painted turtles (Todd McLeish)

biologist for the Rhode Island Department of Environmental Management. “’We bought this turtle for a few dollars when Johnny was 8, he had it for 10 years and now he’s going to college, so we put it in a local pond.’ That’s been the story for hundreds and thousands of kids in recent decades.”

            Red-eared sliders are native to the southeast and south-central United States and northern Mexico, where they are commonly found in a variety of ponds and wetlands. Buchanan said they are tolerant of human disturbance and tolerant of pollution, and they are dietary generalists, so they can live almost anywhere. And they do.

            They breed throughout much of Australia as a result of pets being released, and in Southeast Asia they are raised as an agricultural crop and have displaced numerous native species. In the Northeast, they live in the same habitat as eastern painted turtles, one of the area’s most common species, but they grow about 50 percent larger. Numerous studies suggest that sliders outcompete native turtles for food, nesting and basking sites.

            Despite concerns about their effect on native turtle populations, red-eared sliders are still legal to purchase in Rhode Island and most of the United States, though Buchanan said that in the Ocean State they may only be sold by a licensed pet dealer and cannot be transported across state lines. Those that purchase a slider must keep it indoors and must never release it into the wild, including into a private pond.

            “But people often aren’t aware of the regulations, or they don’t bother to look at them, or they just don’t follow them,” Buchanan said. “We see lots of evidence of sliders, especially in parts of the state where there are lots of people. The abundance of red-eared sliders in Rhode Island is tied to human population density, which means mostly Providence and the surrounding communities. But I’ve also found them in Newport and Narragansett and elsewhere.”

            Sliders are especially common in the ponds at Roger Williams Park in Providence and in the Blackstone River Canal

            While conducting research for his doctorate at the University of Rhode Island from 2013 to 2016, Buchanan surveyed ponds throughout the state looking for spotted turtles, a species of conservation concern in the region. During his research, he also documented other turtle species, including many red-eared sliders.

            “The good news was that while spotted turtles can occupy the same habitat as red-eared sliders, I found a greater probability of occupancy by spotted turtles at the opposite end of the human density spectrum as I found sliders,” he said. “Spotted turtles tend to occur where human population density is low, so at least at this moment in time, we would not expect red-eared sliders to be directly competing with populations of spotted turtles.”

            Nonetheless, Buchanan advocates what he calls a “containment policy” to keep the sliders from expanding their range in the state.

            “It’s mostly about public education,” he said. “We want to make sure people know not to release them in their local wetlands. If we found sliders in an important conservation area – Arcadia, for example – we might consider removing them, though we’re not doing that now.

            “They’re well-established in Rhode Island now,” he added, “so the thought of eradicating them does not seem like a feasible management solution. We just have to live with them, but we also have to try to minimize their spread and colonization of new wetlands.”

            No other non-native turtle from the pet trade besides the red-eared slider has been found to be a common sight in the wild in Rhode Island, though Buchanan said he recently had a report of a Russian tortoise – another popular pet – that was discovered wandering around Coventry.

            For those who want to get rid of a pet red-eared slider, Buchanan doesn’t offer any easy alternatives.

            “You’ve got to be committed to housing that turtle for 30 or 40 years until it dies,” he said. “That’s why this is such a problematic issue. It’s easy to buy a teeny turtle for ten bucks and think it’s no big deal, but that animal is going to live for a long time. When you purchase it, you have to be responsible for it for the rest of the turtle’s life.”

This article first appeared on EcoRI.org on June 24, 2020.

On the prowl

            When University of Rhode Island research scientist Amy Mayer captured a bobcat in Charlestown in 2016, she had no idea where it would lead her or what she would learn from it. But after checking its health, taking a blood sample and placing a radio-tracking collar around its neck, she released the animal as part of a five-year study – the first of its kind in Rhode Island – to learn where the wild cats are found in the state and what habitat they prefer.

            It didn’t stay in Charlestown long.

            “It ended up spending most of its time in Saunderstown near Casey Farm,” said Mayer, whose research is conducted in collaboration with the Rhode Island Department of

Environmental Management. “The interesting thing is that it was always hanging around neighborhoods. I spent a lot of time driving around Plum Beach and other nice neighborhoods keeping track of it.”
            And then it disappeared. She couldn’t relocate it for days and days. Using a telemetry antenna dialed into the collar’s radio frequency, she had to be within a third of a mile of the animal to detect its location. So she kept driving farther and farther afield until she heard the distinct beeping noise that indicated she had found it. In Snug Harbor, where it spent the next several months.

            “We think it moved because of some sort of resource availability,” Mayer speculated. “The habitat in the two areas isn’t all that different, so maybe it couldn’t find enough food and just decided to move. Or maybe it was competition from another bobcat that made it shift locations.”

            Whatever the reason, it helped Mayer gain a better understanding of the ecology of Rhode Island’s only wild feline.

Bobcats are the most widely distributed native cat in North America, living in deserts, mountains, prairies and coastal regions. Weighing up to 35 pounds, they eat a wide variety of small mammals and other prey. In Rhode Island they are believed to consume mostly rabbits,

squirrels and rodents. The animals have been sighted in nearly every community in mainland Rhode Island, but their hotspots are in South County – mostly South Kingstown, Charlestown and Westerly.

And their numbers are increasing.

“It’s really hard to get a good population estimate, since to do that you have to be able to do a trap-and-recapture study, and we’ve learned that they’re very difficult to trap,” Mayer said. “Or you have to be able to identify individuals from photos, which is also difficult because their spot patterns aren’t very clear. But I’d estimate the population to be somewhere between 50 and 100, probably closer to 50.”

To learn more about them, Mayer set up 100 trail cameras around the state – including 40 in South County – to detect where they are found. Bobcats were photographed at 20 of the South County sites and at a total of 40 statewide, but in most cases the animals were only photographed once or twice at each site.

“They move around a lot and don’t park in any one area for long,” she said. “They travel pretty widely, especially the young ones that don’t have an established territory yet. We trapped one young bobcat near URI, and then it spent time in Saunderstown before going all the way to Stonington, Connecticut, and back.”

Loss of habitat is typically the greatest threat to large animals, but bobcat numbers in Rhode Island have increased over the last 80 years at a time when residential development in the region has been quite high.

“It’s a weird conundrum that habitat is shrinking, but for whatever reason, they’re able to survive and they’re doing well,” Mayer said. “In the 1950s they were classified as rare, but not anymore.”

The biggest threat facing the animals now is road mortality. As many as 10 bobcats are reportedly struck and killed by vehicles around the state each year. Others probably go unreported. Route 1 through South County is an especially dangerous place to be a bobcat.

“Of the animals we tracked, they didn’t necessarily avoid areas of high road density. Maybe that’s because roads have the shrubby edge habitats along them that bobcats prefer,” said Mayer.

Trapping of bobcats for their fur is prohibited in Rhode Island, and there is no evidence to suggest that they are poached on a large scale, though Mayer said that a bobcat is occasionally mistaken for a deer and shot during hunting season.

Rhode Islanders who are alarmed at the growing number of bobcats in the region have little to worry about, according to Mayer. "They tend to be secretive, so most people don't even notice when they are in the neighborhood," she said. "People should use the same precuations they do with any wild animal - don't leave pets out unattended, especially in the evening, and keep sources of food secured indoors."
While the objective of Mayer’s camera trap study was to learn about bobcats in the state, the cameras also captured more than 200,000 images of other animals, including deer, raccoons, opossums, turkeys and more.

“We got photos of fishers at 95 out of the 100 sites,” she noted. “We’ll be able to use all of that data for studies of the distribution of other animals in the state as well.”

Most importantly, however, biologists now know a great deal more about Rhode Island’s elusive bobcat.

“We started off with zero information about bobcats in the state, and now we have a huge database of information about them to work from,” concluded Mayer. “It will be super useful for DEM to keep track of their distribution, and we can combine our data with other studies taking place in other states in the area. It has definitely been a successful project.”

This article first appeared in the June 2020 issue of South County Life magazine.

Antioxidant-rich diet reduces stress response during bird migration

                A research team led by a University of Rhode Island ornithologist had birds fly in a wind tunnel to simulate migration and found that birds that consume dietary antioxidants before and during fall migration can reduce the endocrine stress response triggered by long-duration flights.

                The results, published this week in the Proceedings of the Royal Society B, emphasize the importance of protecting habitat with an abundance of available berries containing antioxidants at migratory stopover sites.

                “This reduction in the endocrine stress response may be a major benefit birds gain in fall by eating fruits at stopover sites during migration,” said Scott McWilliams, URI professor of natural resources science, noting that many species of birds select berries containing anthocyanins, a type of dietary antioxidant present in purple-colored berries. “We know birds prefer certain berries that have lots of antioxidants.”

                During long-distance flights that push birds to their physiological limits, levels of metabolic hormones called glucocorticoids become elevated to provide ready-to-use fuel to satisfy high energy

demands, according to McWilliams. But prolonged exposure to glucocorticoids is detrimental and can lead to chronic stress response. The research concluded that the consumption of anthocyanin-rich food attenuates the potential stress triggered by the secretion of high levels of glucocorticoids.

                “We always thought that glucocorticoids were important for birds preparing for migration, and antioxidants were there to mop up the free radicals associated with high metabolism during migration,” said McWilliams. “We tested the hypothesis that antioxidants and glucocorticoids were metabolically complimentary, that is if the birds ate anthocyanins before flying then the increase in glucocorticoids to support metabolism would be reduced.”

                The study was conducted at a wind tunnel at the Max Planck Institute for Ornithology in Seewisen, Germany. Scientists from URI, the Institute, Jagellonian University in Poland and Sacred Heart University in Connecticut collaborated on the project. Funding was provided by the National Science Foundation and European grants.

                The researchers chose as their study subjects European starlings, a common species in Germany that migrates to southern Italy. The test subjects were collected from nest boxes, hand-raised adjacent to the wind tunnel, and put through endurance training for two weeks prior to the experiment. Physiological measurements were then taken before and after the birds’ long-duration flights, some of which lasted up to six hours.

                “The birds that ate anthocyanins prior to flying increased the level of glucocorticoids in their circulation by only about half as much as those that did not eat dietary antioxidants,” said McWilliams.

                Equally important, he said, is that the birds that ate the anthocyanins “showed no other effects on their flight performance. The birds could fly for just as long, they used just as much fat, and everything else was similar. Their performance was the same, but they accomplished that performance while reducing their glucocorticoid response. The antioxidants attenuated the negative effects of the glucocorticoids.”

                McWilliams believes that many species of birds benefit from feeding on berries high in antioxidants during fall migration.

                “We know that lots of other species of birds switch to feeding on fruits in fall and show the same kind of preferences for certain fruits high in antioxidants,” he said. For this reason, land management and conservation efforts for migratory songbirds, especially in the eastern U.S., focuses on providing habitat with an abundance of fruiting shrubs.

                While many varieties of anthocyanin-containing berries are available to birds during the fall migration season, few are available during spring migration, and little is known about how the birds cope with the high levels of glucocorticoids during their northbound flights.

                “We don’t know where they get those antioxidants in spring, or if they do,” McWilliams said. “All animals have an endogenous antioxidant system, so perhaps when dietary antioxidants are less available, they rely more on this internal endogenous system.”

Time to honor the teacher bird

            As spring migration winds to a close and the breeding birds focus their attention on bringing another generation into the world, we often focus our attention on the birds that are raising their chicks in nests close to our homes. We celebrate our daily observations of cardinals and robins and finches, for instance, and we note their progress from nest building to egg laying to hatching to the fledging of their chicks.

Or we pay attention to the big, showy species that we can’t miss at our favorite nature preserve, like ospreys or herons or swans. We feel a personal sense of satisfaction when we see them deliver another stick to reinforce their nest or when we see a tiny face peeking out.

But a great many bird species are unintentionally ignored, perhaps because they’re difficult to observe or are uncommon in our neighborhood or because we don’t even know they exist. Yet they deserve a little respect, too.

So, as the school year comes to a close – and what a challenging year it was – it seems

Ovenbird by Don Blecha/MacAuley Library

appropriate to honor the ovenbird, the mascot of teachers everywhere because it sings a raucous song of TEA-cher, TEA-cher, TEACH!

The ovenbird is among the loudest of the spring songsters – and no, I’m not going to equate that trait with any teachers I know – so they are easy to hear in almost any forest in the area. But they are extremely difficult to see. With a tan back and wings, a streaked breast, and a dull orange stripe through their crown, they blend in well with the forest floor, where they spend most of their lives hunting for insects among the leaf litter.

By now, most ovenbirds are sitting on their eggs in one of North America’s strangest nests. Unlike the typical cup-like nest built by most birds, ovenbirds build oven-like nests – domed structures made of dead leaves and grasses and lined with animal hair – that the birds enter from the side like an old-fashioned oven. Hence their name.

Every year around the first week of May, ovenbirds arrive from their wintering grounds in the Caribbean and Central America and burst forth with their breeding call to announce that they are back and ready to raise a family. And every year when I hear them, I do my best to see one and fail. It can be incredibly frustrating. An ovenbird will be singing loudly seemingly an arm’s-length away and I can’t find it. So I walk a little further and I’ll hear another one close by, and I can’t find that one either.

If I wait long enough, eventually the bird will take a short flight and I might get a glimpse of it, but seldom does it sit still in an easily observed location for long. I guess in that way they may be like a few teachers I know, who prefer to remain hidden from their students after the school year ends.

It’s not until they’re finished breeding later in the summer that I tend to see ovenbirds in more open areas, including in my garden looking for an easy meal. But by then they’ve stopped singing and they’re gearing up for another trip south for the winter.

And that’s not at all like our teachers. While the teacher bird relaxes in the tropics for the winter, its namesake humans are teaching another class full of students. And, when necessary, occasionally bursting forth with a raucous call of their own.

This article first appeared in the Independent on June 14, 2020.

Volunteers document demise of doomed sparrow

            At the 36-acre salt marsh at Jacob’s Point in Warren, Dierdre Robinson wanders among three mist nets she sets up at dawn every morning from late-May through mid-August in an effort to capture the rare saltmarsh sparrows that nest there. The birds are predicted to go extinct in the next 15 to 20 years as rising sea levels flood marshes throughout their range on the East Coast. So Robinson and a team of other volunteers are attempting to document the fate of every nest built and every egg laid.

            “I’m drawn to the exceptions to the rules, and this bird is the exception,” said Robinson, a retired physical therapy professor at the University of Rhode Island who has been interested

Deirdre Robinson holds a saltmarsh sparrow (Todd McLeish)

in saltmarsh sparrows since the 1990s. “They’re non-territorial, they prefer to run than fly, their breeding system is based on promiscuity, the female does all the nest building and feeding, and they don’t really even have a song, just a rudimentary whisper.”
            At one net, she disentangles a female bird to read the numbered band on its leg to trace its breeding history at the site. Checking a log book, she notes that the bird was first banded at Jacob’s Point in 2018 and has now nested there at least three years in a row.

            In the first week of June, the high tides were the highest of the month, and most of the nests were expected to become flooded. If the eggs hadn’t hatched by then, they would probably float away on the tide; if they had, the chicks would likely drown.

            “She’ll probably lose her nest tonight, and then she’ll likely try again next week,” Robinson said of the bird in her hand. “If she nests in a slightly higher location, she might succeed next time, but not if she nests back in the flood zone again.”

            When Robinson photographed a banded saltmarsh sparrow in 2016 at Jacob’s Point – a property owned and managed by the Warren Land Conservation Trust – she was inspired to investigate where it came from. She eventually tracked it to a bird bander in Pinellas County,

Saltmarsh sparrow nest at Jacob's Point (Todd McLeish)

Florida, which gave the bird the distinction of having migrated the longest distance of any saltmarsh sparrow ever recorded.

            The discovery inspired Robinson to contact amateur ornithologist and master bird bander Steve Reinert and launch a research project.

            “We figured that if we found a bird banded in Florida, why couldn’t they find one of ours,” said Reinert, who retired from Lifespan in March and leads bird-banding programs for the Audubon Society of Rhode Island. “Our goal is to find every nest and get bands on every female at every nest and band every male we can, and then determine the elevation and vegetation composition of every nest.

            “If I were more optimistic, I’d say the excitement of the study is contributing to identifying optimal nesting habitat for saltmarsh sparrows, doing it by finding lots of nests and knowing what happens at every nest, and documenting the characteristics of those nests,” he added.

            But it’s difficult to be optimistic for the future of this species.

            “The birds aren’t aware of the tides,” Reinert said. “They just come in, mate, build their nests, and lay their eggs. By experience or selection or whatever, they cluster their nests in a higher part of the marsh. But we had one bird that put her nest in the lower part of the marsh, and her nest got flooded last night.”

            The year’s first nesting attempt by each female saltmarsh sparrow typically fails when the nest is flooded by the highest tide of the month. But that allows the birds to synchronize their next nesting effort with the tides.

            It takes 28 days – the same number of days between high tides – for the birds to build a

Jim O'Neil and Steve Reinert look for sparrow nests (Todd McLeish)

nest, lay their eggs, incubate them, and raise their chicks until they are mature enough to escape the rising tides.

            “If all goes well, their young will be strong enough to climb out of the nest into the high vegetation to avoid being drowned,” Reinert said. “It’s so closely timed that some of the clutch might climb up and survive and others won’t.”

            But as the tides rise higher and higher due to the climate crisis – some predictions suggest it will rise two more feet by 2050 and seven feet by 2100 – the marshes will become completely flooded and the birds will disappear forever.

            Nonetheless, the research team is revealing some unexpected findings about the saltmarsh sparrows at Jacob’s Point. Among the most notable is that the marsh is home to many more sparrows than anyone would have guessed. Last year they documented 84 saltmarsh sparrows at the site – 53 males and 31 females.

“This is a really healthy marsh with a lot of birds nesting here, so we hope that makes it a high priority for possible intervention or restoration,” Robinson said.

            By recording the location of more than 100 nests in the last three years – many found by seventeen-year-old Joel Eckerson, another member of the project team – the researchers have also noted that the birds cluster their nests where the marsh elevation is highest. It’s a strategy to avoid flooding that succeeded prior to this era of rising seas, but not anymore.

            “It’s depressing,” admitted Reinert. “But I guess I do this work out of curiosity. I find us in a unique position to document this species through its period of extinction.”

            Robinson gets depressed when she thinks about the future of the saltmarsh sparrow, too, but she tries to put a good spin on it.

            “Extinction is a natural process, though this extinction won’t be natural – it’s completely anthropogenic,” she said. “But we bring a lot of young people to see the project, and they get excited by it. So I try to channel it into something positive, like preparing these young people to study other species.”

            The fourth member of the research team, Jim O’Neil, is more hopeful.

            “I think this is a way we can figure out how to save this species,” he said. “I’m hoping the birds will make it. Maybe what we learn can help save the species.”

            It’s a sentiment many bird lovers feel. But by all accounts, it’s not realistic. 

This article first appeared on EcoRI.org on June 10, 2020.