The day could not have been better if we had planned it.

It is a well-known fact in birding circles that even exhaustive knowledge of birds, their habits, and their habitats does not guarantee sightings. More often, it produces frustration instead, as expectations go unmet. But delight reigns supreme when one goes out just to enjoy the day, curious to see what turns up.

This was so for us on a recent visit to the Fields Pond Nature Center in Holden. It all began with the arrival of a dozen bluebirds.

The birds were extremely active, zipping from bush to tree and pausing to alight atop the Nature Center, becoming animated roof ornaments. When they settled in a mountain ash tree, their impossibly blue plumage accented the yellow leaves and the bright red berries they had come to eat. Although the day was overcast, there was no lack of color with these birds around.

Robins and hermit thrushes materialized to round out this family tree. Among them all, a few yellow-rumped warblers flitted, alternately gulping berries and snatching insects out of the air.

As we headed toward the boat landing at Fields Pond, we heard an incredible racket. Turning, we observed perhaps 200 or more crows in the air over the ridge. They seemed greatly agitated, swirling like leaves caught in a whirlwind.

The reason for their apparent disgruntlement became evident when an adult bald eagle soared into view. It circled higher, and then seemed to catch an invisible roller coaster as it undulated in the air currents over the hill. Soon the eagle disappeared, as did the crows, but I couldn’t shake the impression that we had just been involved in a more benevolent version of Alfred Hitchcock’s “The Birds.”

Still, it wasn’t over. As we approached the boat landing, we caught sight of a lone bird standing in the shallows of the pond. It was a common snipe.

This stocky, short-legged bird, which resembles the American woodcock, began to forage in the mud. Slowly, it made its way closer until it was less than 10 feet away from us. We were able to see every detail of its beautiful plumage, which no field guide can do justice to.

The bird was obviously fattening up for its migration south. We watched as it stuck its long bill down into the oozy edge of the pond, occasionally catching some succulent invertebrate. After watching for nearly 20 minutes, we quietly backed away to leave the bird to its life-giving feast.

Reluctantly, we returned to the warmth of the Nature Center, where we were told that white-crowned sparrows had been seen around the feeding stations. Sure enough we spotted them perched on the brush pile near the feeders, occasionally darting out to forage on the ground beneath the feeders.

They might have stopped here to refuel for the remainder of their southbound flight, as they breed across Canada to Alaska and the western United States. Even so, it was a treat to see these distinctive sparrows with their bold black and white head stripes.

Soon we had to end our birding day to honor other commitments, but who knows what we would have seen had we been able to continue. A day without expectations sure had produced one surprise after another.

Chris Corio, a volunteer at Fields Pond Nature Center in Holden, can be reached at fieldspond@juno.com