Research Project is for the Birds

One of the most interesting summer days I ever spent was working in a canoe with VCU professor and Prothonotary Warbler researcher Bob Reilly. We spent the day examining bird boxes at Dutch Gap Conservation Area in Chesterfield County, Virginia. There are 160 nesting boxes at Dutch Gap, and we visited quite a few of them that day to collect data for the local Prothonotary Warbler project.

“Prothonotary Warblers are on the watch list,” explained Reilly. “Much of the warbler decline comes from loss of habitat at their wintering grounds. The birds are losing mangrove shoreline habitat to shrimp farming in many small tropical countries.”

 Reilly spends several hours a day, multiple days a week from mid-April through July working on the project. He collects data to monitor conservation success and to support ongoing research on the breeding ecology of this species. In addition, the data he collects is provided to state wildlife agencies and the U.S. Department of the Interior, which issues the permit under which he operates.

Wintering grounds for the birds range from Costa Rica and Panama, to Columbia and Nicaragua. This means the small birds must cross the Gulf of Mexico to winter in the tropics, and then again in the summer to breed in the U.S.

 The birds require nesting cavities over water so all of the boxes at Dutch Gap sit on poles in shallow water near the shore, accessible for us only by canoe. The boxes we checked were all productive so we recorded the number of eggs or hatchlings present. This was done only after I learned to capture the female in a long net with an opening sized to cover the 1¼ inch hole in the nest box.

Once a bird was captured, Reilly deftly examined it, made measurements, weighed it and recorded information from its band before releasing it. He banded a few unbanded adult birds. To my surprise, information from the birds’ bands showed that many of the adults were hatched and banded at Dutch Gap last summer or in previous summers. Many even returned to the exact same box or a neighboring box to breed, some for several years in a row.

If hatchlings were present and mature enough, we removed them from the nest and Reilly gently banded their small legs. The young birds were far more cooperative about the research project than their parents.

We only captured three males out of four attempts throughout the day, and only then if conditions were just right. I say “we” but I was an untrained assistant simply following orders. We had to first visually spot the male with a mouthful of food en route to the nest. To capture the males, Reilly installed on the nesting box a remote control trap door he invented just for this purpose. Once that was in place, we moved away to watch for the male to enter the box to feed the young. At Reilly’s signal, I sprang the trap to catch the bird. The colorful yellow males were larger than the females, but weighed less because the females bulk up for the hard work of laying eggs and raising the young.

Warblers generally live two to three years, if they survive their first year, but we encountered one female that was five years old. Like most birds, young warblers only have a twenty percent or less chance of survival.

Reilly’s dedication and hard work are important to the warbler research project and the birds’ survival. While we can’t control what happens at the warblers’ wintering grounds, I hope the great accommodations and quality care here in Virginia will help contribute to a more stable future for the these beautiful birds.

Too small to band, based on wieght

 

Adults were weighed head-first