MAMMOTH CAVE NATIONAL PARK — Brice Leech walked a narrow path in a wooded area along the eastern bank of the Green River on Thursday, checking to see if any songbirds had become caught in any of the 10 nets he had placed along the path.
He and his team were catching songbirds as part of a survey for the California-based Institute for Bird Populations to help determine why songbird populations are diminishing and what factors play a role in their decline. The official name of the survey is MAPS, or Monitoring Avian Productivity and Survivorship.
MCNP began taking part in the MAPS survey in 2004.
“A lot of what we catch are migratory. They fly down to Central America, South America, Mexico and they will come back here every year and go down there every year, so they are flying that kind of distance twice year,” he said. “Along this corridor, along the habitat on the river, there are about six to eight species in Kentucky that are on the Species of Greatest Conservation Need and that is the reason why we are doing it here.”
The MAPS survey takes place at MCNP from the last week in May to the first week in August and it is done once a week on eight occasions during that time frame.
Leech and his team conduct the MAPS survey at MCNP early in the mornings, starting around 5:30 a.m. They start so early, because that is when the songbirds are the most active, Leech said.
“About the middle of the day it starts to warm up they kind of quiet down,” he said.
MCNP is not the only national park taking part in the MAPS survey. Any public agency, non-governmental group or even individuals can do it.
“There's like 1,200 stations across the country,” he said. “We're all doing it at the same time.”
The MAPS surveys are not conducted during the rain, so on Thursday, theoretically, all 1,200 stations could be doing it at the same time.
“There are 10 day periods for MAPS to occur,” he said.
What each person or entity looks for in conducting the surveys vary. Leech and his team are interested in the songbirds when they are breeding at MCNP, and because of that they skip the first two days in conducting the survey because of the national park's latitude.
“In Florida, they will be doing all 10. You go up to Canada, they may be doing six. We're doing eight,” he said.
The 10 nets Leech and his team set up along the path are placed in a figure-eight pattern. They check the nets once every 40 minutes to see if any songbirds have flown into them.
Because it is easy for the birds to become tangled in the netting, Leach and his team carry small crochet needles that they use to untangle the songbirds. Once they have them untangled, they place them in small fabric bags and carry them back to their survey station, which is in the middle of the woods.
At the survey station, Leech and his team identify the species of the songbirds, as well as their sex. They also try to determine the age of the songbirds, how fat they are and whether or not they have a brood patch.
This year, for the first time, Leech and his team are taking blood samples, but only from the Kentucky Warbler.
Others conducting MAPS surveys are taking blood samples from the American Red Start, the Robin, the Canada Warbler, the Painting Bunting and the Western Tanager.
A researcher at the University of California Los Angeles is working with IBP to gather information about those species of songbirds in particular to see if there is a genetic link between them, he said.
Once they have documented the information, and if the songbird is a Kentucky Warbler, taken a blood sample, Leech and his team places a tiny band on the leg of the songbird. The band shows information has been collected from that particular songbird. In the past, Leech has caught the same songbird twice, once each year, and has talked to people at other MAPS survey stations who have caught songbirds that were once caught at the MCNP MAPS survey station.
“The birds we've caught most of are Common Yellow Throat, Kentucky Warbler, Indigo Bunting, Carolina Wren, Cardinal, Hooded Warbler and Wood Thrush,” he said.
Since Leech and his team began the MAPS survey at MCNP this year, they have caught 13 species of songbirds.
Over the years Leech and his team have noticed how weather may be affecting the number of songbirds they catch in their nets, especially if it is a serious weather event that occurs in either the winter or early spring.
When southcentral Kentucky sustained a flood in 2010, the area where Leech and his team conduct the MAPS survey for MCNP was under 15 feet of water.
“That next year, instead of close to 100 in the season, we got 35 (songbirds). The next year numbers were still down. It may take two years for populations to build back up,” he said. “That's kind of what we are seeing.”
But Leech isn't sure how to prove the affect weather is having on the number of songbirds they catch in the nets, and said it could just be a coincidence.
Since he and his team has started the MAPS survey at MCNP this year, he said they have gotten “some decent numbers” that could indicate that songbird populations are increasing.
“We got 19 birds the first day. Last week we had 18. Good species represented, but at the end of the season we will know if the numbers are cranking back up. If not, what's going on?” he said.
Working alongside Leech on Thursday was Larry Johnson, also a resource management specialist. He and Leech were part of the original group to first do the MAPS survey at MCNP in 2004.
“We are the last two left. We need some more,” Johnson said.
He does the MAPS survey because he enjoys being outdoors, he said.
Leech does it because he grew up loving birds.
“My mom and dad, my dad mainly, he wasn't that into identifying everything. He just enjoyed watching them,” he said. “I've kind of gone off the deep end from that, but I love handling the birds and learning more about them. Trying to help with the research nationwide and internationally that is going on is pretty cool to be a part of that.”
Helping with the MAPS survey on Thursday was Sasha Rohde, who actually works for the U.S. Department of Agriculture in Bowling Green. She volunteered to help Leech and the team.
“I enjoy it. I'm a birder. I'm actually a scientist. I used to work for the National Park Service, but now I work for the USDA. I work in a lab now and it's fun to come out in the field and sit in the woods and look at birds,” she said.