Great blue herons are among the easiest birds to identify. They’re great, they’re blue, they’re herons. Any questions?
Well, yes, I have one. Where do they go during the winter? Until recently, nobody could answer that question. Great blue herons are so widespread in North America that nobody could tell which wintering heron was a year-round resident and which had come down from the north.
Then great blue herons started disappearing from Maine. We now have only a fraction of the nesting herons that we had in the 1980s. In 2007, the Maine Department of Inland Fisheries and Wildlife listed the great blue heron as a species of special concern. We started studying them.
In order to understand a population decline, it’s crucial to know whether they are disappearing because of nesting failure in summer or if something is harming them wherever they go in winter.
Danielle D’Auria is the state wildlife biologist in charge of the study. She organized a large group of volunteers to monitor nesting colonies around the state. Thanks to citizen-scientists in the Heron Observation Network of Maine, or HERON, we have a better idea of the risks faced by nesting herons. The biggest threats are eagles, owls and my wife Sandi.
Every summer, Sandi gleefully accepts another monitoring assignment. Every couple of weeks, she visits her colony to tally the active nests and count the chicks. And every summer since 2009, her colonies have failed. No exceptions. Two years ago, she arrived for her first visit only to find that great horned owls had taken over a nest and forced the remaining herons out. Her more recent colony had an active nest last summer, with three adorable chicks growing fast. Then they disappeared, probable victims of an eagle or owl.
Successful colonies can stay productive for years. Some colonies go dormant for a few years, and then get active again. Nesting failure has always been common, but the rate of failure has increased, especially along the coast. Besides danger from above, herons can also fall victim to nocturnal mammals, such as raccoons.
So, after years of surveying, we had a better idea of what was happening in Maine, but we still lacked knowledge of how our herons fared when they went south for the winter. Personally, I would have bet on Chesapeake Bay.
Last spring, Danielle and her crew managed to capture five adult great blue herons. They outfitted each with a nickname and a GPS collar. “Sedgey” is a male that was trapped in Orrington’s Sedgeunkedunk Stream. Another male named “Snark” was also captured there. “Cornelia” was snagged at the New Gloucester Fish Hatchery. “Mellow” was netted in Orono. “Nokomis” was caught right behind its namesake high school in Newport.
What happened next is a story that gives me goosebumps. Rather than follow similar paths to similar places, each departed in September bound for totally different destinations. Cornelia followed a lazy route that ended at the Great Dismal Swamp in Virginia. Sedgey made a beeline to Lake Okeechobee, Florida. Snark’s signal disappeared for a while, but he finally popped up in Vero Beach, Florida, where he’s been photographed happily perched on channel markers. Astonishingly, Mellow crossed the sea to Cuba, and Nokomis flew to Haiti.
I’m leaving out the details of their wanderings, because I don’t want to spoil the surprise endings. Danielle will be telling their tales during a couple of upcoming presentations. She’ll reveal their sojourns during a free talk at Fields Pond Audubon Center in Holden at 7 p.m. Feb. 17. She’ll then reprise the saga at the Eastern Maine Sportsman’s Show in Orono. Look for her on the calendar at 5 p.m. Saturday March 11. It’s worth your attendance just to find out how to capture a 4-foot tall bird that wields a bill like a stiletto.
If you’re interested in joining the HERON survey team, you can discuss it with Danielle at either of these talks. You can also find information on the IFW website at maine.gov/wordpress/ifwheron/.
In just a few short years, we’ve learned a lot. We now know that populations are declining along the coast but appear to be relatively stable inland. We understand that our herons can go just about anywhere once they leave Maine, even daring to cross the sea to reach tropical islands. We know that our five celebrity herons survived to adulthood because they avoided predation and, more importantly, they weren’t in a colony my wife was monitoring.
Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at email@example.com.