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Early Tuesday morning, three district employees begin an ongoing pilot study of the local bird population.
By DAN DeWITT
© St. Petersburg Times, published May 21, 2001
WEEKI WACHEE -- To the crew counting birds at the Weekiwachee Preserve, Tuesday morning started in the best possible way.
Clay Black, walking down a dirt path faster than some people sprint, ducked into the woods several yards ahead of his co-workers to check the first net.
"Oh," he called back, sounding mildly surprised. "We have one already."
By the time the others arrived, Black was unwrapping an ovenbird from the fine netting. He transferred the tiny and nearly weightless wad of speckled feathers into a cloth bag. A drawstring was pulled tight, and the count was under way.
By noon, Black, an engineer with the Southwest Florida Water Management District, or Swiftmud, Mary Barnwell, a land management specialist with the district, and Margaret Lytle, a Swiftmud lawyer who had taken the morning off to help with the study, had captured 17 birds.
That exceeded the 10 that they expected. But the real significance is not the total number of birds netted, quickly banded and released, but how well the birds survive and reproduce.
Swiftmud workers will return to this station every 10 days during the 90-day breeding season. The idea is to count birds that breed here, not the ones that pass through while migrating. And the study, which began on Tuesday, will likely continue for at least five years, Black said.
"We would like it to go on for 20 years or indefinitely," he said. "The bigger the sample, the better."
By counting adult birds -- some of which will be netted over and over -- the crew will be able to determine how long the birds live. By comparing them to the number of young birds, they will be able to figure out how many young the adults are successfully raising.
The results will give Swiftmud a reading on the health of this 6,000-acre habitat west of U.S. 19, which it purchased for preservation in 1994. The count is a pilot program, and the district eventually plans to expand it to its other properties.
The information the team gathers also will help determine the health of the national songbird population. The monitoring station at the preserve is one of about 500 across the country, said Danielle O'Grady of the Institute for Bird Populations, which is based in California.
There are many gaps in this network, especially in Florida, which has a large bird population but only a few monitoring points, O'Grady said.
"Any station that fills in a hole, like Clay's station in Florida, is very helpful," she said.
Before Black, Barnwell and Lytle could begin catching birds, they had to set up the nets. They met in a parking lot at the southern edge of the preserve at 5:30 a.m., then drove about a mile northwest, to a circuit of nine netting sites that had been chosen previously to provide a variety of habitat. Some were in hammocks, some on the edge of land that had been cleared by the mining company that once worked this property.
The nets were strung between two poles stuck into the dirt about 35 feet apart and, once erected, looked like droopy badminton sets. The three worked intently in the dark to put them up and untangle them -- a job more confounding than straightening out Christmas lights -- before their deadline, which was dawn. They finished just as the sky lightened above the pines and an especially noisy chuck-will's-widow finally stopped its morning song.
They then began the first of several walks around the circuit, which is laid out so it can be covered quickly, especially at Black's pace. The idea, he said, is to limit the trauma to the birds by taking just a few minutes to capture them, make notes about their condition, band them and release them.
The two birds caught on the first pass of the circuit -- along with the ovenbird, a common yellow-throated warbler -- were carried to the tailgate of Black's pickup. He cleared away a hoe and a pair of size-13 sneakers to make room for his logbook and the tackle box that held his banding equipment.
"We've got to get a better organized banding station," he said as he reached into the first bag.
"That's a nice little ovenbird."
It was migrating, probably from wintering grounds in Mexico, so it is not part of the breeding population the team is focusing on. Black banded it anyway, and determined why it was so late in flying north: Its plumage showed it was an immature bird, he said.
"This is its first trip back. He probably didn't match up with a mate."
The common yellowthroat chirped loudly as Black reached in to pull it from the bag, but it relaxed as Black held its head gently between his index and middle fingers and measured its wings and blew into the fine feathers on its breast, looking for remnants of its premigratory fat reserves and worn spots that would show it was roosting.
Like all the other birds, it was weighed, which required it to be placed briefly in a resealable plastic bag. The reading showed about 9 grams, or roughly a third of an ounce. Black then removed one of the smallest bands from his collection, stored in film viles in a tray of his tackle box, and fitted it around the bird's pin-thin leg.
As the morning progressed, the common yellowthroat, true to its name, turned out to be the most numerous species. But the workers also collected, among others, a Carolina wren, a red-bellied woodpecker and an American redstart.
The team members talked about the species and the individual birds. They mostly spoke about markings, idiosyncratic behavior or the hardship of crossing the Gulf of Mexico.
Black examined a black-throated blue warbler and pointed out a white patch on the edge of its wing.
"See that nice white window at the wings? You can tell this bird is at least 2 years old," he said.
When he removed the Carolina wren from the net, he explained that it lives in dense bushes close to the ground -- sometimes, for example, among potted plants.
"It's very adept at getting in and out of close spaces," he said.
"Make sure you keep a close eye on the Carolina wren," Black said as he handed it Barnwell.
"An escape artist, huh?" she said.
"Most definitely."