Capturing a heron (temporarily)
MAIDEN, N.C. —It’s difficult to take your eyes off the photo of the Great Blue Heron taken by the shore of Lake Norman, near Charlotte. A trail camera mounted on a dock snapped the photo. The colors are rich; the light blue sky with wisps of clouds, the deep blue water, the trees and houses on the shore across the lake painted with gold. The sun must have been setting with the picture was taken. And there in the center of the photo is the bird; large and majestic. Sadly, this is also a picture of frustration.
“It was aggravating because there it was and it was not coming to the bait box,” said Chloe Simmons, a junior at Maiden High School. She’s in the environmental club. “But it was exciting to see it and to see how big it is.”
The members of the environmental club were sitting in lawn chairs around the shore of the lake watching for the bird because the students hope to catch, measure and tag the heron. The club is helping with a national study of the great birds. The trail camera was placed to track where the bird goes when people aren’t around to see it. The club members are studying herons and learning how to capture the birds safely. It’s not only for the bird’s benefit but also so they don’t get hurt.
“The last time we caught a bird and performed all of the measurements it took about 30 minutes,” says Jeanna Goodson, an Environmental Science teacher at the school. “After we release the bird, it usually flies a few feet away and then stays around for a bit, getting used to freedom. Then they fly off.”
What to do when you catch a heron
It’s a team effort to catch and study the large birds. Usually a towel is placed over the head to calm the bird. While one person holds the head and beak another person holds the body. Another person then measures the tarsus, which is the leg from the ankle to the knee. The wing core, which is from the top of the wing to the tip, is also measured. Finally the culmen is measured. That’s the part of the beak that runs from the feathers at the top of the beak to the tip. A blood sample from the leg is also taken.
But of course, all of this depends on catching the heron. And so far, the heron isn’t cooperating.
“We put 47 large and small traps around the bait box and it’s almost impossible for the bird to walk around the box and not step in a trap,” says Landon Aldridge, a sophomore member of Maiden High’s Environmental Club.
It only takes a slight bit of pressure on the trap for it to spring closed. The traps are designed to hold the bird’s leg tightly but not injure the bird.
“It was cool to see it and I thought we had it because the leg was clearly in there,” said Aldridge. “We all got out of our chairs and started running down, but when we got about 15 feet away, it pulled its leg out and took off.”
“It was disappointing,” the teen said with a deep sigh. “It was really disappointing.”
Tracking the large bird's movements and energy
Catching and studying the large birds hasn’t always been disappointing for students in the environmental club. In 2014, the students helped capture and study a heron they named Big Blue. It was also on Lake Norman. And that takes us to that study of the great birds.
“Every bird is a mystery, every bird has a story to tell," says John Brzorad, Ph.D., director of the Reese Institute for Conservation of Natural Resources at Lenoir-Rhyne University. “And they all tell different stories but we have to learn to speak the bird’s language. And that’s why we have this technology. It’s how we can learn their story.”
So besides measuring the birds and taking a blood sample, each bird is fitted with a high tech tracking device. Think of it as a solar-powered mash-up of a GPS, a cell phone and a Fitbit. The device allows researchers to find the location of the bird on a map. It’s a standard tracking device. But it also measures how high the bird is above the surface and what the bird is doing. If it is flying, the device can tell if it going up or down and side-to -side. It can also measure pitch, roll and yaw on the x-y-z coordinates.
130 of the giant birds across the country have been outfitted with the devices over the past five years. That includes both great blue herons and great egrets. The devices connect to the nearest cell phone tower three times per day to transmit data.
Data shows where herons go and how much space they need to feed
Brzorad projects a map of Lake Norman on a screen to explain what the data reveals about the heron Big Blue that the students captured and outfitted with the tracking device in 2014. It hasn’t left the area in four years but it's certainly busy.
“Based upon the GPS coordinates, we know this bird from March and April was using 65 acres of shoreline territory to feed itself and its chicks,” Brzorad explained, pointing out yellow shaded areas of shoreline that circled about half of the lake. “But in the next month, the amount of territory has dropped down to 27 acres. The tracking device shows the bird is not visiting the colony at the north end of the lake anymore and he is also no longer visiting any outlying areas. The bird can meet all of its needs in 27 acres along this little piece of shoreline.”
The research shows other herons and egrets have ranges of hundreds or thousands of miles to meet their needs. “These birds don’t make distinctions about what country they are in,” Brzorad added. “We have a bird in Maine that is going there to breed and then going to Haiti for the winter. So it’s important to know Maine and Haiti are connected.”
The study also provides a unique insight into a bird’s life and how it survives. By using the location data, researchers can calculate how far the birds are flying to find food. They will also be able to calculate the energy needs of each bird. In other words, how much food the bird needs each day to provide the energy it needs.
Findings can help with conservation decisions
By combining all of the data, researchers will be able to show the ecological footprint of the bird and how much land it needs to survive. That will be important in conservation work. The information gathered about a great heron named Nokomis is a good example. The data points start out relatively flat. Connecting the points to a timeline reveals that the flights occur just as the bird is arriving at its nesting area. The bird is courting but doesn’t need to fly around much because there are no chicks in the nest. But as the chicks hatch, the daily flight distance increases because the bird needs to gather more food. The distances keep climbing, reaching the highest peak just before the chicks roost, or leave the nest.
“The bird is really flying long distances to gather food just before the chicks roost,” explained Brzorad, who added that the chicks are almost as large as their parents when they leave. “But then once the chicks leave the nest, the flight distance drops dramatically, because the bird can satisfy all of its needs in the area right around the nest."
You can imagine the bird saying, “Whew, that was tough nesting season!”
“This is an opportunity to get close to a bird that we haven’t able to get close to before and learn something about it, said Goodson. “It’s very hard to know where a bird goes and so a tracking device on the back of the bird can teach you so many things we haven’t know before. My students love the idea that we can help with the study. They also enjoy watching where the birds go.”