Invasion from the north

            When feeding birds in the backyard, it’s easy to quickly become accustomed to seeing the same feathered visitors doing the same things day in and day out.

            In my yard, I know that a pair of cardinals will always show up at dawn and dusk.  I know, too, that my neighborhood goldfinches prefer my old rusty thistle feeder to my shiny new one.  And I’ve learned that the local chickadees recognize the sound of seed being poured into my feeders, and they equate that sound to the proverbial dinner bell.

            On any given day the same twelve species of birds seem to arrive, feed and depart at the same time and in the same manner.  But because the “regulars” are so predictable, it’s easy to notice when something new arrives.  And every few winters, flocks of unusual invaders from the north visit our feeders and bring new life to the yard.

            This year seems to be one of those years.

            It started with reports of pine siskins showing up at bird feeders around the state in November. Close relatives of goldfinches, they have brown streaks on their belly and back that

Red Crossbill by Sveinn Jonsson

distinguish them from the goldfinches, though they often show up at the feeders together. I’ve only had a couple visit my feeders so far this year, but I have high hopes for more as the winter progresses.

            Siskins are among a group of birds – including evening grosbeaks, common redpolls, and red and white-winged crossbills – collectively called northern finches that typically spend their winters in the extreme northern U.S. and throughout Canada feeding on pinecones and other seeds. But every four or five years when the cones in the far north don’t develop as usual, these birds travel south en masse in search of food.

            Evening grosbeaks have been making an appearance in the region this month, too, and they are getting birders especially excited, since they are so seldom seen, even in good years for northern finches. These large gold and black and white birds with huge beaks are a memorable sight at birdfeeders, both for their beautiful appearance and for their tendency to travel in large flocks.

            They are particularly notable for their voracious appetites. Most people who feed birds consider themselves lucky to have a flock visit their yard.  But after a week or so, they may not feel so lucky after all.  Like a house full of unexpected guests, a flock of grosbeaks can quickly put a strain on your food budget.

            Flocks of red crossbills have also been observed wandering our region, though they seldom visit bird feeders so they are a bit more difficult to see. But the unusual birds are worth searching for. True to their name, the bill of a crossbill crosses:  the upper mandible curves sharply downward like that of a hawk, while the lower mandible curves upward.  Although the beak appears deformed, this strange adaptation evolved as a means of more easily opening pinecones.

            The only one of the northern finches I’m still looking for this winter is the common redpoll, which, despite its name, isn’t common at all. Streaked with brown, they have a cranberry spot on their forehead, a black chin, and a slightly rosy chest.

            I have my fingers crossed that a flock of redpolls will show up at my feeders in the coming weeks to give Rhode Island the rare superfecta – four winter finches in one season. And then I’ll start wondering who next year’s invading visitors will be.

Offshore turbines could put rare shorebirds at risk

            Last week’s record-breaking auction of development rights for offshore wind power installations near Block Island proves that developers are confident that obstacles to their construction and operation will likely be few. But after just two years of operation of the nation’s first offshore wind facility – the much-heralded Block Island Wind Farm – there is still a great deal unknown about their long-term environmental impact.

A new study of the migratory behavior of a rare shorebird, funded by the Bureau of Ocean Energy Management, suggests that the impact of a growing number of turbines will not be benign.

The rufa subspecies of the red knot, a bulky chestnut shorebird that breeds in Arctic Canada and winters along a wide swath of coastal habitat from the Southeast to the southern tip

Red knot (stock)

of South America, is a federally-threatened bird whose populations have declined precipitously in recent decades. During the spring and fall, they migrate over the Atlantic, and some stop to refuel at select sites along the Eastern Seaboard.

 The birds’ migratory route offshore – as well as their altitude, timing and preferred environmental conditions – was unknown until a group of researchers from the U.S. Fish and Wildlife Service and partners in Canada, New England and New Jersey placed nanotags on 388 knots in the fall of 2016. When the birds flew within detection range of one of 35 radio towers from Cape Cod to Virginia – including four in Rhode Island – their location, altitude and direction was recorded.

According to Pam Loring, the Rhode Island-based Fish and Wildlife Service biologist who led the study, the results indicated that red knots migrate south in fall in two distinct waves.

“Those that came through during early fall went straight southeast over the open Atlantic Ocean and were likely heading nonstop to South America,” she said. Most of those birds probably traveled far to the east of any of the areas targeted for wind energy installations, so those early migrants are unlikely to be affected by wind turbines in U.S. waters the future.

“The second wave came through in November and went more in a southwest direction,” Loring said. “Birds from Cape Cod cut across the mid-Atlantic Bight and arrived in the mid-Atlantic coastal region from New Jersey to Virginia.” Those birds intersected with a large area leased for wind energy off New Jersey.

Most of the birds in the second wave were recorded flying less than 200 meters high, placing them at an altitude in which they would risk colliding with wind turbine blades. Loring said, however, that there were “high uncertainties” in the data about the precise altitude at which the birds were flying.

Still, in a report she wrote for the Bureau of Ocean Energy Management, Loring noted that the study’s elevation results place “the short-distance wintering population at higher level of exposure to potential effects from offshore wind energy development.”

Among the other findings of the study, Loring said that the birds typically departed for migration just prior to sunset when skies were clear and they had a tailwind.

“Using the dates, winds and other conditions, we can predict when their movements would occur,” she said. That means that one option for future management of offshore wind farms is to curtail turbine operations during the time periods when red knot migration is most likely to occur. That strategy is frequently used in the West to protect migrating hawks and eagles from collisions with land-based wind turbines.

A similar study Loring is co-leading with University of Rhode Island ornithologist Peter Paton is examining the offshore movement patterns of piping plovers and roseate terns, two birds on the federal endangered species list that breed in coastal southern New England and probably migrate offshore through areas designated for offshore wind development. A report of the results of that study, which included tagging birds on Rhode Island beaches, is due later this winter.

In addition, Paton is leading a study of the movement of various species of birds and bats around the Block Island Wind Farm, using a tracking antenna installed on one of the turbines.

“There are several thousand tags out there on a wide variety of bird species being studied by other researchers,” Loring said. “So we’ll be looking at data from whatever species happen to come through.”

This article first appeared on EcoRI.org at December 20, 2018.

Researcher: Oyster aquaculture limits disease in wild oyster populations

                A fisheries researcher at the University of Rhode Island has found that oyster aquaculture operations can limit the spread of disease among wild populations of oysters. The findings are contrary to long-held beliefs that diseases are often spread from farmed populations to wild populations.

                “The very act of aquaculture has positive effects on wild populations of oysters,” said Tal Ben-Horin, a postdoctoral fellow at the URI Department of Fisheries, Animal and Veterinary Sciences in the College of the Environment and Life Sciences. “The established way of thinking is that disease spreads from aquaculture, but in fact aquaculture may limit disease in nearby wild populations.”

                Working with colleagues at the University of Maryland Baltimore County, Rutgers

Oyster farm in Delaware Bay (Tal Ben-Horin)

University, the U.S. Department of Agriculture, and the Virginia Institute of Marine Science, Ben-Horin integrated data from previous studies into mathematical models to examine the interactions between farmed oysters, wild oysters and the common oyster disease Dermo.

Their research, part of a synthesis project at the National Center for Ecological Analysis and Synthesis, was published this week in the journal Aquaculture Environment Interactions.

                According to Ben-Horin, diseases are among the primary limiting factors in wild oyster populations. There are few wild populations of oysters in New England because of Dermo and other diseases, and in the Chesapeake Bay and Delaware Bay, wild oysters are managed with the understanding that most will die from disease.

                Dermo is caused by a single-celled parasite that occurs naturally in the environment and proliferates in the tissue of host oysters, which spread the parasite to other oysters when they die and their parasite-infected tissues decay in the water column. But it takes two to three years for the parasite to kill the oysters. As long as the oysters are held on farms long enough to filter disease-causing parasites from the water, but not so long that parasites develop and proliferate and spread to wild oysters nearby, aquaculture operations can reduce disease in wild populaitons.

                The disease does not cause illness in humans.

                “As long as aquaculture farmers harvest their product before the disease peaks, then they have a positive effect on wild populations,” Ben-Horin said. “But if they’re left in the water too long, the positive effect turns negative.”

                He said that several factors can confound the positive effect of oyster aquaculture. Oyster farms that grow their product on the bottom instead of in raised cages or bags, for instance, are unlikely to recover all of their oysters, resulting in some oysters remaining on the bottom longer. This would increase rather than reduce the spread of the disease.

                “But when it’s done right, aquaculture can be a good thing for wild oyster populations,” Ben-Horin said. “Intensive oyster aquaculture – where oysters are grown in cages and growers can account for their product and remove it on schedule – is not a bad thing for wild populations.”

                The study’s findings have several implications for the management of wild and farmed oysters. Ben-Horin recommends establishing best management practices for the amount of time oysters remain on farms before harvest. He also suggests that aquaculture managers consider the type of gear – whether farmers hold oysters in cages and bags or directly on the seabed – when siting new oyster aquaculture operations near wild oyster populations.     

The next step in Ben-Horin’s research is to gain a better understanding of how far the Dermo parasite can spread by linking disease models with ocean circulation models.

                “Everything that happens in the water is connected. There’s a close relationship between the wild and farmed oyster populations and their shared parasites,” he said. “Sometimes ecosystem level effects are overlooked, but in this case they’re front and center.”

Rhode Island Audubon reaches for national accreditation

At Cardi Swamp in Foster, Scott Ruhren and Kyle Hess bushwhacked through thickets, slogged through ankle-deep mud, and traversed stone walls, small hills, and dense forests. Along the way they made note of the various habitats they encountered and recorded as many species of plants and animals as they could find on the 130-acre parcel, which was donated to Audubon in 1995.  

Hess, Audubon’s conservation assistant, called it “wandering with a purpose.” He and Ruhren, the senior director of conservation, cataloged a calling Pileated Woodpecker, several green and wood frogs, an active nest of bald-faced hornets, an orange stinkhorn fungus that smelled like rotting flesh, a solitary Atlantic white cedar tree, numerous shagbark hickories, and a high-bush

Kyle Hess at Cardi Swamp

blueberry shrub, among many others. They also recorded several invasive species – Japanese barberry, Asiatic bittersweet and a large patch of phragmites.

The undeveloped property, which is not open to the public, showed little sign of human impacts, other than the stone wall, a distant gun shot, and the sound of cars on the nearby roadway. 

The visit by Ruhren and Hess was part of Audubon’s effort to seek national land trust accreditation, an arduous process of recordkeeping, property monitoring, and policy updates that requires all Audubon lands be monitored at least once each year in the future – no matter how remote or difficult to traverse. Offered through the Land Trust Alliance, a national organization that aims to strengthen land conservation across the country, the accreditation typically takes several years to achieve. Audubon hopes to complete the process by 2020. 

Audubon’s Executive Director Larry Taft said that land trust accreditation is a way of documenting and ensuring that the Society follows the proper standards and best practices in how it handles land management and conservation. The accreditation process includes a review of everything from the organization’s mission, bylaws and policies to financing, fundraising and volunteer recruitment, with a special focus on recordkeeping and monitoring of all properties acquired throughout the organization’s history. 

“It’s a rigorous look under the hood at everything we do,” Taft said. “It’s all about proving how solid your organization is. And it has helped us to focus, to better understand our strengths and point out those areas where we could improve.  

“The process reminds us that we have an obligation...

Read the rest of the story in the Winter 2019 issue of Audubon Report.

Outlook dismal for rebuilding region's winter flounder stocks

            Winter flounder is one of the most popular fish among recreational anglers and commercial fishermen, due in part to their thick fillets and great taste. Once abundant in Rhode Island waters, their numbers have declined significantly in recent decades, and new research suggests that the warming climate will likely make it impossible to rebuild their stocks to targeted levels.

            The study, led by a former research associate at the NOAA Northeast Fisheries Science Center in Narragansett, concluded that even if fishing were to be curtailed entirely, winter flounder populations are unlikely to rebound.

            According to Rich Bell, who now works as a fisheries scientist for The Nature Conservancy, winter flounder is a cold-water, coastal species that spawns in estuaries like

Winter flounder (Jerry Prezioso/NOAA)

Narragansett Bay and Buzzards Bay during the fall and winter when most other flounders migrate south or offshore. Their eggs and larvae develop in the estuaries during the coldest months of the year.

            “During the 1980s and 90s they were overfished, and it seems that they never really recovered,” said Bell. “We believe that they come into the bays to spawn in winter where they have a thermal refuge from predation. When it’s cold, there are no predators around, giving them time to grow big enough before it warms up and the predators arrive.”

            The concern is that as the climate has warmed and spring arrives earlier and earlier, the predators are now arriving before the larvae have a chance to grow big enough to escape. Common predators on larval winter flounder include sea robins, summer flounder, sculpins and crangon shrimp.

            By combining winter flounder population models with climate models, Bell and his NOAA colleagues projected future population numbers as the climate continues to heat up. They factored in three fishing scenarios into their models: no fishing, moderate fishing representing a small fishery or incidental catch, and fishing at the expected long-term sustainable level assuming the stock was rebuilt to historic levels.

            “We found that as temperature increases, it’s going to be more challenging for the population to recover. And more importantly, even if there is no fishing and the temperature goes up as expected, they may be unable to reach the targeted recovery level,” said Bell.

            A large part of the problem is that winter flounder produce fewer young in warm waters. The species is now rarely caught in southern estuaries like Chesapeake Bay, and numbers are way down in Delaware Bay and Long Island Sound.

            “There might be so few in Long Island that there are subtle signs of inbreeding occurring,” he said.

            Bell notes that winter flounder are not headed toward extinction. Populations are healthy in colder water regions like the Gulf of Maine, Georges Bank and the Canadian Maritimes. But the continuing declines in southern New England raise challenging questions for their management.

            “It becomes a larger issue of what do we as a society want to do,” Bell said. “Do we want to stop fishing them entirely? Do we want to fish them all now before they’re gone?”

            While Bell wasn’t willing to weigh in on those questions, he said the phenomenon of cold-water fish species experiencing a decrease in productivity and an increase in mortality is not exclusive to winter flounder. Other researchers are documenting similar results in other species as ocean temperatures rise.

            Whether the target levels for rebuilding winter flounder stocks are even plausible is another question. Bell said that those targets are based in part on data collected in the 1960s and 70s before significant warming had occurred and when the species was reproducing at high levels.

            “Rebuilding plans developed assuming constant rates for demographic variables such as growth, reproduction and mortality may not be realistic for stocks like winter flounder,” he said.

The research was published in September in the Canadian Journal of Fisheries and Aquatic Sciences. 

This article first appeared on EcoRI.org on December 7, 2018.