Northern harrier sighting adds spice to birding trip

Once again a trip to the Taylor Bait ponds produced some wonderful bird sightings. I had ample opportunity to be grateful for finally visiting this birding hotspot that I had previously only read about.

The immature great blue heron and the great egret were still around. They were both foraging on the far side of the pond, the heron perhaps a dozen or more feet behind the egret. Even so, the heron still appeared larger. I hadn’t until then considered the size difference between the two, but in fact the heron is more than 6 inches taller than the egret. It weighs more as well – 5.3 pounds as opposed to the egret’s paltry 1.9 pounds – appearing remarkably hefty. This effect is further enhanced by its regal, dark grey plumage. The egret was much more slender and delicate, refined in all of its stark white splendor.

The prized sighting of the evening, however, was of a northern harrier, also known as a marsh hawk.

I first caught sight of the bird as it flew low over the north side of the pond, lovely and buoyant in flight. It was coursing above the pond’s emergent vegetation; at times it flew low enough for me to see its dark-brown upper body plumage with its tell-tale white patch at the base of its long tail. It alternated hovering in place with deft twists and turns as it hunted for food. Its beautiful russet underbody feathers caught the rays of the setting sun and seemed to glow.

Abruptly it changed direction and began following the edge of the pond that parallels the road. I hunkered down against the hood of my car and watched it come closer. As it flew by no more than 20 feet away, I got an excellent view of its piercing eyes and owl-like facial “disks.” These disks help it to locate prey by sound as well as, or in the absence of, sight, effectively funneling sound into its large ear openings hidden underneath its feathers. A harrier can hear the movement of a vole or mouse from up to 12 feet away.

Having no luck at the pond, the hawk began rising, circling far above tree level. I followed it with my binoculars as it reached the top of its spiral and leveled off, heading west toward Pushaw Lake. As I followed this bird, I caught another farther away in my binocular field. This second bird also looked to be a harrier, but at that distance I couldn’t be sure. It appeared to be headed southeast, and this caused me to wonder if it was actually migrating.

Hawks don’t usually migrate so late in the day, however. They like to fly when the air is most turbulent, usually from late morning through the middle of the day. They take advantage of northwest winds and also rising columns of warm air – called thermals – which give them lift and saves them energy. The hours after sunrise and before sunset are usually saved for hunting.

But who knows? Maybe conditions were just right for migrating, despite the late hour. Perhaps the bird was an experienced, well-fed adult that knew an ideal stopover site farther along the journey. Here in Maine we are entering prime hawk migration time, although northern harriers have a more protracted migration than do other hawks For example, broad-winged hawk migration is known to peak in September, more specifically around the second or third week of the month. Large numbers of these birds are recorded passing hawk-watch sites along the eastern seaboard at this time. Harriers, on the other hand, may be seen migrating anytime from late August through December.

Despite all that is known of bird migration, much is still a delightful, intriguing mystery.

NEWS bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net