Thursday, August 20, 2009
A Bird in the Hand
by Dale Quinby, College of the Atlantic
A young American Redstart on its first migration, following the Atlantic coastline south, is likely to find itself out over the Gulf of Maine some miles from shore. The bird is tired and has used up most of its fat reserves. Then, down below, it sees a small patch of green amid the blue. The exhausted bird heads down, landing in the shrubbery on the island. Its first impulse is to feed on the berries in the bushes. But as it flutters around, it finds itself suddenly caught and held by some invisible force. Disoriented and frightened, the redstart flaps its wings and thrashes about trying to free itself but is only held tighter.
"Well hi, squirtums," says David Holmes as he carefully unwraps the strands of thin plastic mesh tightly tangled around the bird’s feet, neck, and wings. Many of the all but invisible threads are hidden under the feathers and have to be coaxed out by touch, in a painstaking process. Once he frees it from the net strung along the path, Holmes carefully puts the bird in a paper bag. Back at the Appledore Island Migratory Station (AIMS), Holmes and his team of volunteers will weigh, measure, and band the bird before releasing it. The tiny metal band on its ankle bears an identification number and instructions in the event that the bird is recaptured at another location. The volunteers at the station will handle between 3,500 and 4,000 birds every year.
Holmes started the bird banding station on Appledore in 1981 as a hobby project. Since then, many more volunteer banders and helpers, jokingly referred to among themselves band-aides, have joined the effort. Research for doctors’ theses has been done at the station as well, including that of Sara Morris. Morris, an associate professor of biology at Canisius College, took over running AIMS in 1990. Because most of the birds caught on Appledore are migrant visitors heading to other countries, most of the research projects at AIMS focuses on migration movements and how the birds use places like Appledore where they stop to refuel for the rest of their trip.
Conservationists have been very interested in how birds use these pit-stops recently because of the plight of the red knot, a small shore bird which migrates over 9,300 miles from the Arctic to Tierra del Fuego every year. The red knot stops at Delaware Bay on its journey to feed on the horseshoe crab eggs there. Due to overfishing, there weren’t enough horseshoe crabs laying eggs to support the red knots, leading to a population crash that started in the late 1980’s and continues today. Though state officials are working to correct the problem by limiting horseshoe crab harvesting, the situation raised public awareness about the importance of these stop-over spots.
Appledore is an ideal place to study the needs of migrating birds because of its isolated position out in the Gulf of Maine. Islands are perfect for research because they are contained, so researchers can tell exactly what plants and animals are there. When they know exactly what is there for birds to eat, it is easier to tell what is being eaten. Conservationists can then apply results from small scenarios like this to other places. As Holmes puts it, "If people decide these birds are worth protecting, how do we do it?"
Part of learning how to protect birds is learning how they behave. That way humans can change how they act to avoid conflicts since birds are unlikely to change their habits for our convenience. Recently at AIMS Kristen Covino, as part of her doctorate thesis, looked at how birds decide when to travel. Covino captured birds of half a dozen species that migrated at night and were also hardy enough to endure the experiment without sustaining any harm. These birds were then held in cages for the day with unlimited food to keep them in good shape before they were released at dusk. Covino attached capsules filled with glow-stick liquid to the birds’ rumps so that she could see where they flew after being released. If they flew off Northeast, she knew they were resuming their migration. If they settled into the bushes, then they were staying the night on the island. Covino used this information to look for patterns in how birds decide to migrate.
The purpose of Covino’s yet-unpublished study was to understand what factors go into making the bird’s decision, like the bird’s physical condition, weather, wind patterns, and season. Knowing when birds are more likely to migrate and where they might go can help humans avoid interfering with the migration by changing our habits, like where we choose to route airplanes. Flocks of birds can cause airplane crashes, so those involved in air traffic control are very interested in research like Kristen’s to help make airplane flights safer. "Some of the best studies have been funded by the US Department of Defense," says Holmes.
Airplanes aren’t the only dangers birds encounter on their migrations. "It’s all the standard stuff," says Holmes. "Habitat destruction; chemical issues with food supplies; hazards like cell towers; windows, which are the number one non-natural killer of birds; and cats, which are the second." Wind turbines are an increasing worry for the researchers at AIMS as more and more people look to wind power to solve the energy crisis. The state of Maine is now looking to supplement the oil it uses with wind power in the near future, using large off-shore wind farms.
AIMS has been part of the effort to test the effects of wind turbines on migrating birds since a turbine was installed on Appledore Island in 2007. The banders check the area around the turbine twice a day for any birds that hit it. So far they haven’t found any casualties, but Holmes warns against attaching too much significance to these results. "You can’t extrapolate about a little kind of thing like this." The programs proposed by wind-power advocates are on a much larger scale and would need a great deal more study to understand the impacts. "We hope the state of Maine will be environmentally conscious about this," says Holmes.
The Appledore Island Migration Station is the site of a great deal research that helps us understand what birds need and how to give it to them, but perhaps one of the most important services it provides is simply the opportunity for volunteers and visitors to see birds up close and personal, to hold one in hand and feel its heart beating. A cedar waxwing, a beautiful bronze bird the size of a cardinal, sitting on a child’s hand makes that child think about birds and what they are doing more than any number of class-room discussions ever could.
"We do have an impact on people," says Holmes. "At least one of our banders became a bander because she experienced the Appledore banding station, and that happens with some frequency." Holmes also tries to educate visitors at the station about conservation, explaining how to handle the birds safely and encouraging people to keep their cats indoors, as they are the second-most non-natural killer of birds. "We at least try to plant small seeds," says Holmes.
[Photo by Colleen Cassidy]