The warbler’s fall migration is fast approaching, and for those of us who have never experienced it, it can be a little intimidating but very informative.
Warbler 101 started out as a writer on South Padre Island, Texas for the past decade. Being immersed in the differences between males and females, as well as other songbirds that a novice bird watcher was completely unfamiliar with, and the famous FALLOUT, the learning curve started upon arrival for reasons obvious.
First of all, keep your cool and catch the warblers as they come. Males are more colorful than females and you will see both. Fortunately there were three memory cards in my possession, because they were all full.
However, the mainstay of this article is the fall warbler. Some of the males are considerably less colorful than in the spring, but many are not, so they can be identified, especially if new birders are familiar with spring warblers first. You may also not find all of their Spring Warblers in the fall, as some take different routes during each migration.
For meat and potatoes, depending on where you may be in the country during migration, the warblers that look alike throughout the year are adult birds – Gray Warbler, America, Canada Warbler and the Warbler Clan – Mourning Warbler, Dusky Warbler, Both Warblers, Kentucky Warblers, Nashville, Hooded, Yellow-throated, Orange-crowned, Virginia and Connecticut Warblers. These are mainly ground warblers, Vermivora and Leoithlypis, with the exception of the Tennessee Warbler. Not all are listed individually here.
Those that change their appearance in “winter” include Tennessee, Prairie, Cape May, Black and White, Prairie, Palm, Chestnut, Blackpoll, and Yellow-rumped Warblers. Basically these are all of your current Setophaga Warblers, not all of which are listed here.
Any birds not hatched in the summer that you are looking for them undergo a full post-breeding moult in late summer where they are gradually replacing their feathers. This means that all adults will have fresh plumage in the fall, NOT the spring birds.
Your juvenile birds after leaving the nest have juvenile plumage for a short time. Before migrating in the fall, they perform a partial (preformative) moult to first year fall plumage. Everything changes except the tail feathers and many wing feathers. When they molt the following summer, these feathers are over a year old.
Many warblers will maintain winter territory and some will defend their areas with call notes. Perhaps the smaller units need to be better seen to assert territorial aggression. Some species, like the ubiquitous Spring Warbler, which can be found in high density, may not need bolder plumage because their numbers are sufficient to thwart the threat of usurping their territory.
You’re armed with a bit of data to possibly better identify fall warblers, as well as harden your credentials in many cases. Remember that many females can show basic identity to male plumage. Look for the basic similarities, and consider Stephenson and Whittle’s The Warbler Guide as a reference tool.
Deb Hirt is a wild bird rehabilitator and professional photographer living in Stillwater.