Five of us sat around a table inside Carpenter Nature Center in Hastings on a chilly night in early November, waiting for night creatures. We each wore a headlamp to help guide us in the dark and warm jackets because we were going to be spending some time outdoors.
The main thing we had in common was an abiding fascination with Minnesota's smallest owl, the Northern saw-whet owl. Some of these tiny birds, about the size of a robin, pass through Minnesota on their fall migration. On many nights in October and November a line of almost-invisible mist nets is unfurled near a stand of evergreens at Carpenter, located near where the St. Croix and Mississippi rivers meet.
An outdoors speaker broadcast the saw-whet's monotonous "toot-toot-toot" courtship call into the darkness, sounding like the warning beep of a truck backing up. This sound helps lure the owls toward the nets and we had high hopes that one or more owls would stop to investigate.
Checking at 9:15 (we did this every 20 minutes), our headlamps revealed a tiny owl in the net. A volunteer carefully extracted the little owl from the weave and gently placed it in a cloth bag for the trip back to the center, where it tipped the scales at about 98 grams. "Almost surely a female," said Jen Vieth, the nature center's director, as she felt its chest to detect muscle mass, revealing a bird in good shape for its migration.
Saw-whets average about 3 to 4 ounces, the same as three double A batteries or three ballpoint pens. Males are smaller than females and most of the owls caught in nets are females or birds hatched just months ago. This female dominance in the nets is one of the things the banding project hopes to shed light on.
Vieth measured the length of the owl's folded wing before attaching a small, lightweight metal band to its leg (issued by the federal bird banding lab and stamped with a unique identification number). Then, after spending 15 minutes in a box in the dark, so its eyes could readjust to darkness, the little owl was released to continue its journey.
We all were energized by this encounter with the tiny owl, because on some nights no saw-whets fly into the nets. Then, at 10:15, another saw-whet was untangled from the nets and taken indoors to undergo the same process — weighing, measuring, assessing, banding, time in the dark, then release. By midnight, when the nets were rolled up, three saw-whet owls had been captured.
A similar scenario was taking place that night across the continent, a monitoring effort by partners in Project Owlnet, with more than 125 banding stations in the United States, Canada and Mexico.
At Carpenter and all other banding stations, these activities require a federal banding permit.
Why do they do it? These efforts are helping build the knowledge base about the movements and natural history of these owls. Before the banding effort began in the mid-1990s, they were considered very rare. Now we know that their population rises and falls over a period of several years, with surges likely linked to food availability (small rodents are their favorite prey item).
Little has been known about this owl because they are nocturnal, active at night. Banding stations like Carpenter's are helping researchers map the owl's range and when and where they migrate.
"Saw-whets tend to be pretty loyal to their migration route," Vieth says, and Project Owlnet is helping connect the dots between where the birds breed and where they spend the winter.
Author and researcher Scott Weidensaul says, "Saw-whets are the perfect combination of a ferocious predator in a small, nonthreatening package — cute and cuddly to the human eye, but with all the gravitas of the largest carnivore."
Everyone around the banding table would agree. These tiny raptors have a presence, a charisma that draws attention, and you wouldn't want to be a deer mouse anywhere in their vicinity.
St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for a number of newspapers and magazines, can be reached at valwrites@comcast.net.
Owl facts
The saw-whet's repeated tooting has been compared to the sound of a saw being sharpened on a whetstone.
The smallest owl in our region, saw-whets have bright yellow eyes and a large, rounded head with no ear tufts.
One of the most common owls in forests across northern North America (and across the U.S. in winter), saw-whets are highly nocturnal and seldom seen.
They weigh about the same as 3 AA batteries, or 3 ballpoint pens.
Project Owlnet
Find out more about owl banding at Project Owlnet's website: www.projectowlnet.org
