|Blue-Gray Gnatcatcher by Jackie Bowman|
Invasion of the gnatcatchers
There is a tiny gray and white bird with a longish tail that you might know. If you don’t, it’s probably just a matter of time.
I’m referring to the blue-gray gnatcatcher, an avian sprite nicknamed the “twig fairy” by birding guru Pete Dunne for its dance-like foraging technique.
For pure energy, the gnatcatcher has few rivals. The bird seems to be in constant motion, making it easy to detect but challenging to follow with binoculars.
Gnatcatchers are quite vocal, and once you learn its wheezy, high-pitched voice you’ll realize this bird is surprisingly common in neighborhoods and forest preserves alike. In fact, finding one in DuPage County has never been easier.
This wasn’t always the case. One of my birding friends recently referred to the blue-gray gnatcatcher as the “poster bird for range expansion.” Translation: it’s a traditionally southern species that has spread across the Great Lakes region in a big way.
“Their breeding range has moved north by about 200 miles over the last 25 years or so,” said Doug Stotz, senior conservation ecologist at Chicago’s Field Museum. “I actually think that blue-gray gnatcatcher may be a climate change winner.”
The numbers don’t lie. I looked at Spring Bird Count records for DuPage County since 1975, the first year of data collection. Zero gnatcatchers were found in 1975-1978, and less than 10 were spotted in the years 1979 to 1983. But sightings picked up in the late 1980s and hit triple figures for the first time in 1996 when 104 gnatcatchers were seen.
Spring Count totals in 11 of the last 14 years have been 300 or more, with a high of 550 in 2014. Bird Conservation Network data for the Chicago region also indicate a population boom.
I’ve noticed the upward trend in my own Glen Ellyn backyard. I went seven years before seeing my first blue-gray gnatcatcher at home, in 2004. I was thrilled! Little did I know how common this experience would soon become.
This summer, in fact, the presence of gnatcatchers was so consistent that I’m convinced a pair nested close by.
So, what’s going on? Stotz has a few theories. Because blue-gray gnatcatchers are insectivorous and winter widely in the Southeast U.S., he said, milder winters may be proving advantageous to the species.
“Beside this, I suspect that restoration of oak woodlands helps them in the Chicago area,” Stotz said. “They like oaks and they like things pretty open.”
The subject of range expansion recalls a few other species that are creeping northward with greater frequency. Yellow-throated warbler, summer tanager, Carolina wren and northern mockingbird are examples of “southern” birds that now breed in the Chicago region. But none approach the expansion success of the blue-gray gnatcatcher.
Identifying this bird is easy. I mentioned the gnatcatcher’s wheezy call, which stays in your head once you know it. Visually, the bird’s obvious field marks are a blackish tail with white edges (like a junco) and a conspicuous white eye-ring.
The hyperactive motions of the blue-gray gnatcatcher can clinch the ID, too. Its relatively long tail flicks from side to side when the bird is foraging in trees, likely a strategy to scare up small insects. Sometimes it momentarily hovers.
Gnatcatchers will be with us a few more weeks before starting their southerly migration. Some will travel to Mexico and Central America; many stop in Florida, where the species is resident throughout the year.
Next April, the twig fairy will return, bringing with it enough nervous energy to impress even the kinglets. If you ever wondered what a cup of Starbucks might do for a bird, watch and listen for the blue-gray gnatcatcher, a migrant on a mission.
Copyright 2017 by Jeff Reiter. All rights reserved.