A major difference between spring and fall migration is the sound. In the fall there isn’t much to hear. Songbirds are moving through in good numbers with warblers, vireos, flycatchers, tanagers, orioles and others busily looking for insects so they can fatten up for the flight ahead, but they mainly do it in silence. You will hear the odd juvenile attempting to perfect its singing skill but the efforts usually result in partial notes with just a hint at who the originator is. With breeding over for another year, there is no territory for the adults to defend so song is unnecessary.
Combine the lack of audible clues and add plumage that can be quite different from the spring along with juvenile birds that may look nothing like the adults and you have a real challenge for bird identification. The only positive outcome of fall birding is that often the birds are moving through slowly because they are not in a rush. There is still plenty of food and they may hang around longer during the day than in the spring.
Publisher of Ontario Birding News