The springlike weather we had last weekend seemed just right for birding a few choice spots.

My first stop was Hills Beach in Biddeford. The tide was near its lowest point, exposing a flat, wide expanse of sand. I headed toward the spot where the Spurwink River empties into the Atlantic, hoping to see some interesting sea ducks or perhaps some shorebirds. I wasn’t entirely disappointed — I caught a small flock of red-breasted mergansers as they flew swiftly upstream, their white wing patches flashing in the early afternoon sun.

In North America this merganser’s breeding grounds encompass the wild Arctic tundra and boreal forest of Canada and Alaska, as well as small ranges in Maine and the Great Lakes States. They are most often seen here along the coast, near estuaries and in protected bays, during winter. I was surprised to learn, from reading their species account in “The Birds of North America Online,” that they are a late-breeding duck whose young often do not fledge until September.

On the way back from Biddeford, I stopped at the Wildlife Sanctuary viewing platform that overlooks Spurwink Marsh in Cape Elizabeth. I didn’t have high expectations of seeing anything, as there were a number of people there, but I was pleasantly surprised.

The first treat was a gorgeous female marsh hawk, otherwise known as a northern harrier. She flew in from the left, emerging from behind the shrubs and tress of the marsh’s border. Her level of flight allowed me to see her beautiful, bright russet and buff underbody, as well as her deep chocolate-brown upper body. The telltale white patch at the base of her long tale also was visible.

She descended from tree-line level to directly over the marsh, her flight seemingly as light and as buoyant as a moth’s. She coursed low over the wetland in what appeared to be a specific pattern, at times suddenly dipping down into the vegetation in pursuit of prey. She was most likely going after small mammals such as mice, whose movements she can easily hear due to the owl-like “dish” of feathers framing her face. Among raptors, harriers are distinguished by this feature, which enables them to locate prey much more by sound.

The harrier soon disappeared far across the marsh, but I was about to receive yet another treat.

A sudden commotion among some birches bordering the marsh caught my attention. I noticed a crow fly up suddenly with an alarmed squawk — a merlin was right on its tail. The crow managed to evade the small bird of prey, and the falcon, probably realizing it had lost its advantage of surprise, took off across the marsh, swerving and diving between the islands of vegetation. I imagined it was hoping to flush sparrows out of the grass.

The merlin’s flight was markedly different from that of the marsh hawk. It was swifter, more direct and powerful, with precise maneuverability. It was breathtaking to watch.

After a few passes over the marsh, the merlin changed tactics and landed on what appeared to be a weathered old tree stump, electing to hunt from its perch.

At that time the harrier again came into view, trailing a contingent of crows intent on harassing it. The lead crow dive-bombed the hawk a few times; the hawk didn’t seem to react to this, just continued coursing over the marsh grasses. As the company again disappeared into the distance, I looked for the merlin, which had vacated its perch — I wondered if it had any luck in securing prey.

All in all, it was certainly a good birding day.