Banding Saw-whet Owls
at Hopkins Memorial Forest
Williamstown, Massachusetts
Northern Saw-whet Owls (Aegolius acadicus) were once thought to be year-round residents in their breeding range. Today they are known to be a highly migratory, as well as irruptive and nomadic.
A network of saw-whet owl banding stations open each fall throughout North America to capture and band these small owls. These banding stations are unified under Project Owlnet, whose goal is to "support the expansion of a network of migrant owl banding stations, advocate the use of relatively comparable netting protocols, and to improve communication and coordination between owl banding stations in North America." Project Owlnet has recommended trapping techniques and banding protocol to assure uniformity of procedures at all banding stations.
The banding station lat 42 43' 20" long 73 13' 30" elev: 825' at the Hopkins Memorial Forest in Williamstown, Massachusetts is run by banders Drew Jones and Ken Schmidt, supported by a growing number of volunteers.
A total of 86 owls were banded in 2001, and 159 (including 3 foreign recaptures) in 2002. In 2002 the banded saw-whets consisted of 135 females, 5 males, and 19 undetermined (Brinker), and 55 hatch year, 65 second year, 39 after second year (Pyle). Also captured in 2002 was a very irate screech owl. Barred and great horned owls could often be heard calling in the woods nearby. Hopefully some of the owls banded at the station will be recaptured at other stations in the years to come. This will help researchers understand more about the migratory patterns of these small owls.
At dusk the station's mist nets are opened and an "audio-lure" is played in close proximity to them. Three 2.6x12meter nets are placed in a single line in a path in the woods. The audio-lure consists of the repeated "toot-toot" mating call of the male saw-whet owl. Curious migrating owls investigating the call are caught in the nets. The nets are checked each hour and careful observations are made and recorded of the temperature, wind speed, wind direction, and cloud cover.
Once a saw-whet is caught in the mist net the banding process begins. The nets are strong enough to hold, but not harm, the owl.
Drew begins the delicate task of removing the saw-whet from the mist net. The nets are checked at least once an hour.
Once removed, the owl is transfered in a bag from the mist net to the banding shed.
 The owl is delicately placed in an empty can and weighed. This is an important data item to know.
Here Ken and Drew are banding a saw-whet owl. Each band has a unique number so that if the owl is recaptured the data collected from the two banding stations can be compared. Using special pliers, the band is placed on the saw-whet owl's leg between the "knee" and the foot. The owl is not hurt during this procedure.

Two measurements of the wing are made. One is the length of the wing chord (the longest primary feather) and the other is the wing flattened out. By using a discriminate function based on chord length and owl weight developed by David Brinker, founder of Project Owlnet, the sex of the owl can be determined within 95% accuracy.
Another important measurement is of the tail feathers. These feather molt uniformly so they are either all "new" or all "old". This is one of the data items recorded along with the molt pattern of the primaries and secondaries. By examining the molt pattern of saw-whet owls their age can be determined.
The lighter brown feathers on the left are worn and scratched and therefore older. The darker brown feathers on the right are new. If a bird has all new feathers, it is likely a "hatch year" bird, meaning it was born and fledged this past breeding season. The underside of the wing also shows the age of the feathers. Those with a pinkish cast are new feathers, while those without are old.
NOTE: The picture above (and to the left) are not from the same bird.
The uniform brown feathers on this bird - with little wear or tear - indicates that this bird is a "hatch year" bird.
"Are you guys done yet?"
The ear of the saw-whet owl is highly evolved.
Here you can really see the asymetrical disk shape of the saw-whet owl's head.
The length between the nostril and the end of the beak is measured using dial calipers.
The color of the owl's eyes is compared to a chart and recorded. The eye color "seems" to be greener on younger saw-whets.
Another feature that is examined is whether the beak is "black" or "horned". This saw-whet has the classic black beak.
This saw-whet has a "horned" beak. Note the slightly lighter color on the tip of the beak.

Another important observation is the amount of fat the owl has. The fat appears as white areas under the skin and is a good indictor of how well the owl has been feeding. By gently blowing the feathers away from around the "armpit" of the owl one can check for fat deposists. This measurement is recorded on a scale of 0 (no fat) to 3 (a lot of fat). Two to five-thousand saw-whet owls are captured and banded each year by Project Owlnet. About 1-5% of these banded owls are subsequently recaptured. The Williamstown banding station is one of an incresing number of saw-whet owl banding stations in Massachusetts.

Once all the measurements have been completed and recorded in the log book it is time to release the saw-whet back into the wild. Hopefully this little owl with the band #43-588, will be recaptured by another banding station on a future day.
videostills & text by Chris Gentes & Heather McQueen