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(updated 15 Dec 2007)

In 1999, Hilton Pond Center for Piedmont Natural History became the southernmost site in a national network using night-time banding to study dispersal of Northern Saw-whet Owls (Aegolius acadicus). This northern species breeds primarily in the northeastern and western U.S. and in southern Canada (green area on map below) and overwinters mainly in the central U.S. and the Atlantic Coast states (blue area on map).

Through October 1999, only four Northern Saw-whet Owls (NSWO) had ever been banded in South Carolina--the first in 1960 and the latest in 1972; none had ever been banded in South Carolina's Piedmont region. At Hilton Pond Center in November and December 1999, Bill Hilton Jr. netted and banded seven of these diminutive owls that perhaps migrated in from the forests of Canada but may have come from a population that breeds in the southern Appalachians of North Carolina.

NSWOs are captured by playing an audiolure (endless-loop tape recording) of the owl's monotonous "toot-toot-toot" call from dusk until dawn at high volume. Owls are attracted to the sound and, as they approach the tape deck's speakers, fly into a triangle of 60mm-mesh mist nets that are 12 meters long and 2.6 meters tall. Nets, checked hourly through the night, are not deployed during wet weather or when temperatures are below 25 degrees F.

Although Northern Saw-whet Owls are sexually monomorphic (i.e., males and females look alike), there is a measurable size difference between the sexes; females generally are about a third larger than males. Researchers elsewhere have determined saw-whets can be sexed with greater than 90% accuracy by comparing an individual owl's wing chord and mass.

After the initial seven bandings in November and early December, 13 additional nights of playing the audiolure in mid- and late-December 1999 and early January 2000 did not result in the capture of any new or banded Northern Saw-whet Owls at Hilton Pond Center. It is suspected that overwintering saw-whets leave the South Carolina Piedmont at latest by mid-March, when they are known to start showing up in good numbers at more northerly migration banding sites.

In the fall of 2000, an audiolure was played dusk to dawn at Hilton Pond Center starting on 31 October--about a month earlier than in 1999--to determine when NSWOs actually begin to arrive in the Piedmont. The first capture came on the night of 30 November--a year and one day after the first local bandings for this species. Six additional nights of netting resulted in no other owls. In 2001, the first capture came on 27 November, just a few days earlier than the earliest local record. Plans are to begin playing the audiolure and running night nets in early December 2007 and continuing through the middle of the month. No NSWO were captured on the evening of 5-6 December; the next net night was 14-15 December when we finally netted our tenth NSWO (see table above).

Note 1: Netting attempts on three nights in early December 2004 produced no owls. No netting attempts were made in the winter of 2002-2003 because of knee surgery on the owl bander, or in winters since because of bander illness or eye surgery.

NOTE 2: One brown-phase Eastern Screech-Owl (Otus asio)--itself apparently attracted by the NSWO tape--was caught in the same net with a saw-whet on 5 December 1999.

Click here for information about Other South Carolina Bandings of Northern Saw-whet Owls.

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