Tuesday, November 28, 2017

It's bug versus bug in fight against invasive species

            The mixed hardwood forest on the edge of the town of Dalton in western Massachusetts looks healthy to the untrained eye, but the researchers from the University of Massachusetts who visited the site every few weeks last summer are anything but untrained. They quickly noted the small holes made in some trunks by foraging woodpeckers and distinguished them from the even smaller holes made by wood-boring insects. And staring into the canopy they observed that many of the trees were in the early stages of decline.
Consisting primarily of ash and red maples, the forest is owned by the nearby city of Pittsfield to protect its public drinking water supply. But it also serves as a living laboratory to test a variety of methods for controlling the emerald ash borer, an iridescent green beetle native to China that has killed hundreds of millions of ash trees in the eastern and central United States, Ontario and Quebec.
The invasive beetle was discovered near Detroit in 2002 and slowly expanded in all directions, reaching New York in 2008, Massachusetts in 2012 and New Hampshire a year later.
Spathius galinae, a parasitoid of emerald ash borer. (Jian Duan USDA)
While it hasn’t yet been found in Vermont or Maine, it is only a matter of time before trees there will also start dying. The beetle is expected to kill almost all mature ash trees in the region in the next decade or two.
But that isn’t stopping researchers from trying to control the invasive beetle and find a way to protect future generations of the trees from succumbing. While several trees in the Dalton forest have been injected with a systemic pesticide to test whether adjacent trees will benefit from the treatment, the forest is primarily the site of a series of biological control experiments to determine if the emerald ash borer’s natural enemies in the Far East might succeed at keeping the insect in check here as well.
As UMass research fellow Ryan Crandall wandered the forest, he carried with him two prescription medicine bottles capped with a fine mesh. Inside the bottles were coffee filters embedded with emerald ash borer eggs, and inside the eggs were the larvae of Oobius agrili, a tiny parasitic wasp that is one of several insects that scientists hope will do in the U.S. what they do in China – control emerald ash borer populations so native ash trees can continue to thrive.
Crandall and his assistant, Sebastian Harris, were seeking the perfect trees on which to hang the medicine bottles – ash trees that aren’t too far gone yet but that exhibit numerous woodpecker holes suggesting the trees are infested with emerald ash borers. Most of the larger trees they examined were already near death, but eventually the researchers selected a couple of smaller specimens and proceeded to hammer nails in their trunks and hang the pill bottles on the nails. Soon, they hoped, the parasitic wasps would emerge and seek out more emerald ash borer eggs in which to lay their own eggs.
Although Crandall and Harris spent just 30 minutes at the Dalton site, they were far from finished for the day. They had five more stops to make at similarly infested forests in Massachusetts, New York and Connecticut, where they left behind a total of 1,400 emerald ash borer eggs parasitized by Oobius agrili....

Continue reading the rest of this article in the fall 2017 edition of Northern Woodlands magazine.

Wednesday, November 22, 2017

Nocturnal feeder visitors

            Before construction was even finished on my house many years ago, I had already put up several birdfeeders in the backyard, and I’ve been keeping them filled throughout the colder months of the year ever since. If you haven’t put out your feeder for the year yet, it’s definitely time. In addition to the regular winter visitors, I have high hopes that this will be one of those unusual years when we’ll have some rarities from the far north dropping by, like redpolls, evening grosbeaks and red crossbills.
            But don’t think that it’s just birds and squirrels that are attracted to birdfeeders. A wide variety of other creatures are, too. And if you get into the habit – as I have – of briefly turning on
the back porchlight and glancing at the feeders before going to bed at night, there is an excellent chance that you will spy some unexpected neighbors dropping by for a bedtime snack.
            I first started paying attention to my nocturnal feeder visitors when I noticed that large
Cartoon by David Chatowsky
quantities of birdseed was disappearing during the overnight hours when I assumed all the seed-eating birds were asleep. It wasn’t long before I discovered a parade of wildlife scavenging spilled seed from beneath the feeders and a few adept critters climbing on the feeders and knocking more seed to the ground.
            A pair of gray foxes were the first night-time animals I noticed in the illuminated area around my feeders. Slightly larger than their more common red cousins, gray foxes sport a conspicuous black tip to their tail and a black “mane” running atop their tail’s entire length. When I turned on the light, they glanced toward it and then went back to slurping up sunflower seeds from the ground.
            My continued vigilance with the backyard light occasionally turns up at least two different striped skunks that must live nearby, one with a wide white stripe down its back and tail and another whose white stripe is thin, crooked and mottled with black. In all my years of watching, I’ve seen just one opossum, and it just strolled through the light without stopping to eat any seeds.
            My favorite nighttime visitors have been flying squirrels, three of them with big ears, huge eyes and a thick flap of fur between their front and hind legs allowing them to soar from tree to tree. They frequently chase each other around the feeders and then play peek-a-boo behind a tree trunk when they see my face in the window. Like several of the more common daytime birds, the flying squirrels take one seed at a time and disappear into the forest to eat it before returning for another morsel.
            Lately, my feeders have been regularly assaulted by a family of five raccoons. When I flicked on the light the other night, I saw one tugging at a big chunk of suet, another was hanging upside-down on a tube feeder sucking out the seeds, and a third was on the ground gobbling up what the tube sucker had spilled. The other two animals were perched comfortably above the feeders high in a tree, probably digesting a big meal compliments of yours truly.
            But I’m not complaining. My nocturnal visitors are highly entertaining, and I’m happy to have them. Besides, it could be worse. At least no bears have found my feeders. Yet.

This article first appeared in The Independent on November 16, 2017.

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.