Bird banding at Bremer Sanctuary provides vital information

A new project was started at Bremer Sanctuary this spring with the banding of the nest box nestlings. Bird banding is a tool that enables biologists to obtain information about birds, much of which could not be acquired in any other way. Each nestling is fitted with a special, lightweight aluminum leg band that is inscribed with a unique nine-digit number.

The nestlings need to be 12-15 days old, depending on species, and currently acquiring their flight feathers. At this age, their legs are full size and since they do not add fat or muscle to this limb, the same size bands are also used for the adults.

Putting bands with unique numbers on birds allow scientists to keep track of each individual bird when it is caught again. Some of the questions bird banding allows are: How long do birds live? Where do birds go (migration)? What birds are present at this site? How are bird population numbers changing over time? How many young birds were hatched each year?

The banding of birds in the United States requires a federal banding permit, issued by the U.S. Geological Survey. Nancy Redman, education coordinator for Bremer, recently acquired her sub-permit with the Lincoln Land Association of Bird Banders. Redman has been volunteering for LLABB for eight years and has extraction certification for use of mist nets in capturing adult birds. She also has trained in Wisconsin for trapping and banding owls and hawks.

Bremer Sanctuary boasts a 50-nest box trail that spans two miles. The target species for occupancy is the eastern bluebird with other species, tree swallows, house wrens, black-capped chickadees and tufted titmouse also taking up residence in their nest boxes. Breeding season for all of the named species occurs from mid-March until mid-August. Redman monitors the 50 boxes once weekly from April 1 through Aug. 31 and records the findings each week.

Banded nestlings in the nest for the Bremer Sanctuary 2022 season included eastern bluebirds and tree swallows. This is not a tally of their total nest box seasonal contents; it is only representative of the birds banded.

Tree swallows banded, 44 nestlings in 12 boxes (all in different boxes) and one adult in one box (sitting on eggs).

Eastern bluebirds banded include 72 hatchlings in 14 boxes. The eastern bluebird recorded 19 clutches total. A clutch is a group of eggs produced or incubated at one time. Monitoring data shows four of the 14 boxes held multiple clutches, box #3 housed three eastern bluebird clutches. Boxes #12, 29 and 49 each housed two clutches of eastern bluebird and one nest box, #6, housed tree swallows in June and eastern bluebirds in August.