A light-sensitive geolocator, which weighs about 2.5g (©Scott Weidensaul)
The geolocators are miniature, backpack-mounted data-loggers, continuously monitoring light levels for up to two years, from which we can determine the rough latitude and longitude of the migrating owl. The tiny units are custom built by the British Antarctic Survey, and have been used to study the migrations of wood thrushes and purple martins, but never saw-whet owls.
This week we began fitting saw-whets with geolocators at our Hidden Valley station, and will soon be doing so at all three of our sites. The harness is made from thin, tough Teflon ribbon that figure-eights around the bird's body, holding the geolocator high in the middle of the back. A short stalk sticks up above the feathers, with the light sensor at the tip. The entire unit and stalk are encased in a light, thin shell of epoxy to protect the innards from sharp owl beaks.
A saw-whet, fitted with a geolocator and ready to go. The sensor stalk protrudes an inch or so above the feathers on the back, continuously recording daylight and darkness. (©Scott Weidensaul)
(A special thanks to Marge Gibson and her staff at the Raptor Education Group in Wisconsin, who tested the geolocators and the harnesses on three of their captive saw-whets, even going so far as to create nest boxes with natural flicker- and pileated woodpecker-sized entrance holes, to make sure the sensor stalks didn't interfere with the owls' ability to enter and exit the cavities.)
We were also grateful to York University grad students Maggie McPherson and Callie Stanley for giving up their (Canadian) Thanksgiving holiday to come south to help with the work, and to give us the benefit of their geolocator experience working with thrushes and martins under Dr. Bridget Stuchbury.
From left: Callie Stanley, bander Nate McKelvie (front), Maggie McPherson, Pat Trego (rear), Nada Farah, Baha' Ishaq (rear), Ika Rani Suciharjo and Maria del Mar Contaldi. (©Scott Weidensaul)
Finally, we were delighted this week to welcome a number of the international interns from Hawk Mountain Sanctuary, which is not far from Hidden Valley. Marie del Mar Contaldi from Argentina is working on a master's on vulture and condor biology; Nada Farah from Lebanon serves as the country's Important Bird Areas coordinator; Baha' Ishaq from Palestine is an undergrad at Bethlehem University and the only licensed ringer (bander) in the Palestinian territories; and Ika Rani Suciharjo from Indonesia is a high school biology teacher with extensive experience in environmental conservation. As you can see from the picture, they were thrilled with their first encounters with saw-whets.