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WaterMatters

District Assists With Migrating Bird Research

bird research pics
Top: Marianne Korosy conducts her research on migrating birds.
Bottom: Mary Barnwell, senior land management specialist, and Clay Black, senior professional engineer, assisted.

In the early morning hours volunteers flushed birds out of the brush and into an awaiting net. But the birds didn’t stay in the nets long. They were carefully captured and banded in an effort to assist a University of Central Florida (UCF) doctoral candidate with her research on migrating birds.

In January, District employees Mary Barnwell, senior land management specialist; Clay Black, senior professional engineer; and Michelle Dachsteiner, environmental scientist, assisted Marianne Korosy with organizing volunteers, setting up mist nets and banding captured birds on the Weekiwachee Preserve in western Hernando County.

A long line of mist nets, which are made of fine nylon mesh and are difficult for birds to see, was set up across the open fields. The nets were strung between metal poles using a special system Black devised for the preserve’s hard rock soils. More than 30 volunteers from the local Audubon Society and the Florida Ornithological Society helped flush the birds out of the brush and into the nets. This labor-intensive exercise takes about six hours to complete.

Only District staff and researchers who have specialized training and federal and state permits were allowed to handle the birds.

Barnwell and Black have been banding birds for many years, but Dachsteiner is new to the activity. “It was a wonderful experience,” said Dachsteiner. “But I found it takes a lot of time, effort and patience to be a good bander.”

Although volunteers could not touch the birds, they were rewarded with the opportunity of taking close-up photographs of them.

Over the past 20 years, national bird censuses have shown a downward trend in the population of grassland birds. In fact, state and federal wildlife agencies now list several as species of concern.

Researchers are trying to determine if the decline is caused by impacts to the northern summer breeding grounds, resulting in reduced chick production; or impacts to the southern wintering grounds, resulting in lower over-winter survival. The District is cooperating with the UCF to study the utilization, diversity and abundance of listed sparrows on District lands. This is the second year of the program.

Last year’s banding found that three types of sparrows were using the Weekiwachee Preserve as winter habitat.

This year’s goal was to determine if the banded birds would return to the site. Birds that return to a specific site have a greater chance of surviving the winter than other birds because they spend less time moving from one area to another searching for food. This trait is known as “site fidelity.” However, while birds with site fidelity may spend less energy searching for food, they are also at a much greater risk of dying if the site is altered and can no longer provide the resources they require.

Research at the Weekiwachee Preserve has already proved to be very successful. During this year’s two-day event, 27 birds and six different species were banded.

A swamp sparrow banded in last year’s efforts at the preserve was also captured. Korosy was elated with their findings. “Typical recapture rates run at less than one percent, so this is a great find from a banding perspective and attests to some degree of winter site fidelity in this species,” said Korosy. “It was one of seven swamp sparrows banded last year.”

Site fidelity is also an important consideration for land managers when deciding which preservation lands to purchase. Birds showing site fidelity require large areas of undisturbed habitat, which can be difficult and expensive to obtain. Lands with no site fidelity can be managed using numerous small areas scattered across the region at a much lower land cost.

March–April 2009
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