Last fall, I watched and attempted in vain to photograph several little birds fitting among low-lying bushes at a particular spot in the woods.

Eventually, I was able to get a good look at one and identify them as golden-crowned kinglets. Fitful for kinglets, they moved constantly. They sat still for only a second or two as they moved from one branch to the next. Most of the time, they remained concealed by leaves.

The other day, I walked by that same exact patch in the woods and noticed two small birds flitting among the bushes. My instinct was to move on without getting a better look, as I assumed they were golden-crowned kinglets that wouldn’t let me photograph them anyway.

Without looking closely, the birds appeared to be about the same size and color and had the same mannerisms as kinglets. I did eventually stop to get a better look at the birds, however, and discovered that they were not golden-crowned kinglets, or even any type of kinglet at all. They were warblers.

Small, squarish white markings on the wings gave the birds away as female black-throated blue warblers. They were not the fancy-colored male black-throated blue warblers that we would see in a field guide with dark blue head and back, black throats and bright white bellies. These birds were drably colored and nondescript other than the tell-tale white markings on the wings. 

The experience reminded me that we shouldn’t make assumptions when it comes to birdwatching. The easy assumption would have been to identify those birds as golden-crowned kinglets and move on, but in this case, I would have been wrong. 

Similar to last week’s column that featured a photograph of a male scarlet tanager in its yellow fall plumage, this was a good lesson in plumage differences depending upon season and sex. In the case of black-throated blue warblers, males retain their spring-like plumage in the fall, but that plumage differs greatly from that of females. Many other warblers and songbirds, however, look very different in the fall than in the spring.

Throw in the fact that many of the birds passing through New England in the fall are first-year birds that have not attained adult plumage yet, and identifying birds can be quite the challenge for birdwatchers of all levels.

It is interesting to note that most of the confusion and challenge of fall birdwatching is due to migrating songbirds, such as warblers, tanagers, grosbeaks and buntings. Most of our year-round birds look the same or similar regardless of season or sex. There is a little confusion in identifying chickadees, titmice, nuthatches, blue Jays, and woodpeckers.

There are exceptions, of course. Male and female cardinals have different plumages, and distinguishing first-year cardinals of either sex from female cardinals can be tricky. A good look at the bill usually offers a pretty good hint. First-year cardinals have dull bills and adult female cardinals have brightly colored bills.

Goldfinches are also year-round birds in New England, and they do not look the same in the winter as they do in the summer. Gone in the winter is the bright yellow plumage that the male shows off during the breeding season. Those eye-catching feathers have been replaced with dully colored ones.

Fall migration may be beyond its peak for the year, but unlike the spring migration that is fairly condensed, the fall migration stretches on for a much longer time period. Even after the songbirds have mostly flown south of New England, the fall duck migration continues. The ducks will remain until the water freezes or even continue into next spring on waters that remain open throughout the winter.

Yes, the fall migration can be challenging and even frustrating at times. But it’s also a time to say goodbye to our migrating songbirds until next spring and rekindle our appreciation for our year-round birds that will carry us through the winter.