The process of loon banding presents a challenge even before a loon is ready for a band on its leg. If threatened by something such as an approaching boat, a loon will dive underwater, making it impossible for researchers to grab the bird. However, if a loon has chicks that are too young to dive, the adult is more likely to stay on the lake surface. Banders work at night, approaching quietly in the darkness, before turning on a spotlight when they close in on the loon. The light is so bright that the loon cannot see the boat, and the loon is scooped up with a net.
If a loon looks as if it might dive despite the light, banders imitate or play sounds of chicks in distress. The sounds momentarily confuse the loon, which will likely stay on the lake surface rather than abandon its chicks.
“Everything is very quiet and calm to that point, but things get a little more hectic when you scoop it up because the loon is huge and strong and fighting,” she says. “Then you get it into a position where it can’t hurt itself, hold it, take blood samples. If it’s not (already) banded, you put bands on it, and take bill measurements and other measurements for body size. You release the adult and chick together.”
Banding and behavioral observations gave Byrd two key statistics. First, she was looking at questions of presence/absence — where loons are living and successfully having chicks, and where they are living but not pulling off young. Second, she considered site fidelity — how likely loons are to return to the same lake year after year.
“Thanks to banding, I can look at how often birds come back to a territory, which is going to help understand if that’s a preferred habitat,” Byrd says. “If there’s one lake with a different bird every year, we can start to guess that that’s not a good territory or conversely, it’s a great territory and they’re fighting hard every year and every year someone is getting kicked out. But that’s a little less likely because loons are good at maintaining their territory.”