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December 20, 2022

Bird banders at the Rushton Woods Banding Station and the U.S. Geological Survey’s Eastern Ecological Science Center Bird Banding Laboratory have documented an incredible movement of one northern saw-whet owl during its fall migration.

A woman biologist stands in a banding station shed at night and reads the band numbers on a small owl.
Stephanie Egger, biologist with the U.S. Geological Survey’s Eastern Ecological Science Center Bird Banding Laboratory, reads the federal band numbers on the leg band of a northern saw-whet owl recaptured at the Rushton Woods Banding Station in Pennsylvania. This owl was originally banded in Thunder Bay, Ontario. Credit: Aaron Coolman.

Each fall, bird banders across North America work through dark, cold nights to document the movement patterns of the northern saw-whet owl. Over 150 stations participate in a large-scale collaboration called Project Owlnet, which began in the 1990s to try to understand the cyclical migrations, habitat use, and population dynamics of these mysterious birds.

On November 8, 2022, a northern saw-whet owl was captured at Rushton Woods Banding Station in Pennsylvania, just twenty miles west of Philadelphia. The owl was captured wearing a leg band issued by the North American Bird Banding Program (NABBP), which is administered by the U.S. Geological Survey’s Eastern Ecological Science Center Bird Banding Laboratory (EESC Bird Banding Laboratory) and the Bird Banding Office of the Canada Wildlife Service. Since 1920, the NABBP has collected and managed bird banding and encounter records with the goal to provide critical data to track the status and trends of bird populations for developing effective bird science and conservation management.

When the Rushton Woods Banding Station reported to the NABBP that they had captured 1104-04123, staff immediately recognized that something was potentially amiss. When compared to other northern saw-whet owl movement records in the database, this bird had covered an unusually large distance eastward between where it was originally banded in Ontario, Canada, and its recapture location in Pennsylvania. Staff requested further verification from the banding station to confirm this report.

Two nights later this bird was recaptured again at the same banding station and the banders took photos of the bird and leg band confirming the report. This owl was indeed the same owl (1104-04123) originally banded as a hatch-year bird in October 2021 at Thunder Cape Bird Observatory, a banding station on the northern shore of Lake Superior in northwestern Ontario, nearly 900 miles (over 1400 km) away from Philadelphia! Northern saw-whet owls can be resident or long-distance migrants. If they nest in Pennsylvania, they primarily nest in the northern part of the state, but also in mountainous forests near the Mason-Dixon line. Many northern saw-whet owls move southward in winter, with large concentrations in and around the Great Lakes. This recapture was unusual for the Rushton Woods Banding Station, as northern saw-whet owls recaptured in this part of Pennsylvania have not been banded as far west as this one was.

An additional twist of fate would come when a few nights later Rushton Woods Banding Station hosted a visit by a local birding club which included Stephanie Egger, a recent addition to the EESC Bird Banding Laboratory. The same owl was recaptured yet again on this night and the banders were delighted to put the owl in Stephanie's hand for her to verify the band number herself.

In total, the Rushton Woods Banding Station captured this specific owl seven times over ten nights, suggesting that the surrounding area may have provided a good place for it to rest and refuel for continuing its migration south to Maryland, West Virginia, Virginia, or North Carolina, for example. Or perhaps it will decide to overwinter in Pennsylvania. Northern saw-whet owls winter in dense forest and the Rushton Woods Preserve, where this owl was captured, is an 86-acre mature woodland protected and maintained by Willistown Conservation Trust. Rushton Woods Preserve is also part of an Important Bird Area in Chester County, Pennsylvania and is recognized by the Audubon Society for the valuable bird habitat it provides.

Map showing line between Thunder Bay, Ontario and Philadelphia, Pennsylvania.
Map showing the minimum distance traveled by one northern saw-whet owl from where it was originally banded on the north shore of Lake Superior in October 2021 to where it was recaptured in November 2022 near Philadelphia, Pennsylvania, a journey of nearly 900 miles. Credit: Stephanie Egger, USGS.

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