A local look into the world of bird banding¬
A local look into the world of bird banding — the process of tagging birds in order to study migratory patterns and behavior.
When it comes to travel, many of us seek to lose weight before leaving. We are inundated with ads from gyms that will get us beach-body ready.
Meanwhile, those birds you hear in the trees behind your house may instead be packing on the grams, doing the exact opposite as they get ready for a long trip of their own.
And it is in the process of their migration that they might find themselves delayed in a mist net — think a nearly invisible volleyball net — at Washington College’s Foreman’s Branch Bird Observatory just outside Crumpton. They will be carefully pulled from the delicate netting by the hands of trained researchers, placed in a mesh bag and taken to a rustic cabin, where they will be measured, banded and set free.
Jim Gruber is the banding director. Having grown up in Chestertown, he started banding birds in the mid-1970s in Tolchester. In the mid-1990s his banding efforts moved to a farm called Narnia near Chestertown. Then, 20 years ago, the station moved to its current home at Chino Farms. Both properties were owned by Dr. Harry Sears.
Field Ecologist Maren Gimpel joined the team in 2006 after assisting with seasonal bird research in a number of different locations in the United States, Canada and the Caribbean. She and her husband came to Chestertown for a summer research gig and were invited to remain on. They were due in Tobago though, but came back after that job ended.
Sears donated Chino Farms as a legacy gift to Washington College, which in 2011 took over the nonprofit organization previously established for the bird observatory. The site has become the college’s River and Field Campus.
“One of the last recoveries we had, though, of a bird that we had banded was actually banded at Narnia. It was recovered in June,” Gruber said in an interview over the summer. The bird was a grackle, at least 20 years old.
Last year, the Foreman’s Branch team banded nearly 15,000 birds, along with capturing in its nets another 7,000 birds that were already banded. In the fall tally, the white-throated sparrow came out on top with 1,463 of them caught.
“White-throated sparrows we band more than anything pretty much every year. Every once in a while, song sparrow wins. But it’s almost always one of the two. And you think, ‘Oh it’s another white-throated sparrow,’ but it’s still amazing to think how many there are and where they’re going,” Gimpel said.
The observatory notched 1,036 song sparrows in fall 2017 for second place. Maybe this will be their year.
The observatory’s focus is on the spring and fall migration seasons.
Gimpel likened the migration seasons to the difference in population in Ocean City between winter and summer.
“So during the spring, you have this huge movement through — like beach traffic on Friday in the summer — of all these birds leaving South America and Central America and Mexico and moving up to their breeding grounds,” Gimpel said. “Some of these birds are migrating past us, like the Baltimore oriole. They breed up into Canada. And in the fall it’s even more birds, because hopefully each pair has created offspring.”
So why are these birds making these trips? Why is the blackpoll warbler eating so much it’s body weight goes from 10 grams to 24 grams, to the point that Gruber said the bird is squishy to the touch? Why does the godwit — a crow-sized shorebird — fly nonstop for 8,000 to 11,000 miles over the course of week to the point that, as Gimpel said, they begin metabolizing their organs and arrive nearly skeletal at their destination?
Gimpel said the current thinking among scientists is that these birds evolved in the tropics of Central and South America, land without changing seasons. She said some began moving north to see what was available. She spoke about the ample space, arboreal forest and associated insects for food that would have been present in Alaska after the glaciers receded.
“The idea is that it was to take advantage of more space and more food,” Gimpel said.
During a tour this summer of Foreman’s Branch, Gruber extricated a female Baltimore oriole from a net, her feathers darkly stained from the mulberries she was gorging one. She was so covered in juice that she looked more like she had been in a fight, than at an all-you-can-eat berry buffet.
Foreman’s Branch is busy during the migration seasons. The team is logging birds. They note the age, either less than a year old or more than a year for birds not having been previously caught. They check gender, if they can tell it, which is not always easy for species with males and females having the same color patterns. They measure wing size and body mass. All of it is inputted into a federal research system that scientists can access as part of other studies.
Gimpel said the process takes about a minute.
The nets are checked frequently when they are up, which is only about five hours a day. The team also watches the weather very closely. Birds are fine if they are upright in the rain, but that is not the position they usually end up when caught in a net.
“Working with wildlife, the first rule is that we are excruciatingly concerned with the welfare of the animals that we are studying,” Gimpel said. “So we pay really close attention to make sure we are checking the nets on a regular basis and any kind of situation changes, we will close nets.”
Gruber spoke about some of the changes he has seen at Foreman’s Branch in its 20 years. Chino Farms was in row crop production when he first arrived. Sweet corn is no longer grown there and the trees in the wooded areas have gotten bigger, leading some species to change their migration itinerary.
“Habitat has a lot to do with the presence or non-presence of certain species,” Gruber said.
Also, in regards to habitat, Gruber said they are starting to see Kentucky warblers again at Foreman’s Branch following an absence. Their numbers began dropping when trees were cut down near utility lines in the area about nine years ago.
“The Kentuckies must have really liked that spot because they disappeared from breeding in that area almost in a couple years. And now they’re coming back, so we hope,” Gruber said.
And it is not just habitat changes here, Gruber said. Cutting down of rain forests in the tropics plays a role in the birds migrating through the Eastern Shore, as does clear-cutting of trees for mining operations in Canada.