Pennsylvania Game News - September 2022 - 47

TRACKING TECHNOLOGY
Saw-whet owls are a puzzle, in part, because
of size.
If the birds were just a bit larger, scientists
could put satellite transmitters on their backs
and " track their path all over the earth, " said
Scott Weidensaul, a founder of the Ned Smith
Center for Nature and Art and its long-running
saw-whet owl banding project. But they're too
little to carry even the smallest versions.
This might help.
The Motus Wildlife Tracking System is a
growing collection of radio receivers shared by
researchers across the world. There are hundreds
stretching from Canada south through the Appalachians,
with Pennsylvania a " real linchpin " in
the system with 40 or more.
Those receivers track the movement of migratory
animals - down to butterflies - previously
captured and outfitted with battery-powered
nanotags weighing as little as 0.3 grams, or about
one-four-thousandth of an ounce.
Nanotags appropriate for saw-whet owls can
last years. That could allow scientists to answer
questions and confirm theories.
It's exceedingly rare, for example, for Ned
Smith volunteers to capture adult male sawwhets.
They've handled only about a dozen in the
last 24 years, out of roughly 12,000 birds overall.
" So it's quite literally about one in a thousand, "
Weidensaul said.
One theory suggests that's because, rather
than migrate, adult males remain in the breeding
grounds of Canada and northern New
England year-round. They move only
locally, looking for woodpecker holes
surrounded by plentiful rodents for
nest sites.
They " seem to have made an evolutionary
decision that it's better to risk starving and
freezing to death in the north " than it is to be
unprepared when females return in spring to
breed, Weidensaul said.
The Motus system could confirm that.
It might also divulge just how mobile - and
sometimes whacky - these owls can be.
Most bird species, Weidensaul noted, return
to the same general areas to breed and winter
every year. Saw-whets exhibit no such " site
fidelity. " He points to one female monitored
over three years. She wintered in southwestern
Virginia some years, along the New York-Canada
border in others. She nested in Quebec one year.
The next, she nested in western Pennsylvania
and, failing there, promptly moved to New York's
Adirondacks to try again.
" No bird does that, " Weidensaul said. " No
bird moves 150, 250 miles from one nesting site
to another. It's just craziness. "
The Motus system could show whether most
saw-whets likewise are wanderers and explain
how far saw-whets migrate.
The Ned Smith Center has money to outfit
saw-whet owls with nanotags as soon as the
Motus array is large enough to justify the expense
and effort. Weidensaul hopes that will be the case
within two years.
" We've had these questions for a long time.
We've just kind of been waiting for the technology
to catch up, " he said.
In the meantime, for additional
information on saw-whet
owls, check out the video
available at the Game Commission's
YouTube channel.
SEPTEMBER 2022
47
Pennsylvania Game News - September 2022

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