November is one of the best months to see rare and unusual birds in Massachusetts. Many of those rarities are young birds, lost on their first migration. Flycatchers, hummingbirds and tanagers top the bill this month, but literally anything can turn up—and often does. (See the table at the end of the article for a list of recent November vagrants and your chances of seeing one.)
The most common reasons for vagrancy, where birds appear lost and outside of their “normal” range, are:
- Weather. Migrants prefer a tailwind and clear skies to navigate. When birds hit bad weather, such as rain, fog or strong winds, they either land and wait it out, or continue and hope to make any navigational corrections later. That’s especially true when flying over water, when landing is not an option. If the wind is strong and in the wrong direction, birds may simply give up fighting it, and let themselves be carried downwind. Such “drift” migrants may take a few days to recover before heading off in the right direction.
- Misorientation. Sometimes (probably genetically) there’s something wrong with either the compass or the map in a bird’s head. Common navigational problems result in birds flying in exactly the opposite direction (“reverse migration”) as may be the case with Painted Bunting and Fork-tailed Flycatcher; or confusing the east and west axis (while getting north and south right). In such cases the bird ends up in the wrong place, but thinks it’s where it should be. These birds tend to stay (often attempting to over-winter). Such a “genetic” mistake may be helpful for a population, as these pioneers may find entirely new places to breed or winter. This may be what we’re seeing with fall hummingbirds and Cave Swallows.
- Dispersal. After either a good breeding season, or a local food shortage, birds may disperse away from the normal range. Examples include rails and doves and probably many of the western species such as Western Kingbird and Yellow-headed Blackbird that are often found here in years of reproductive success.
- Association. Some birds just end up in the wrong flock. This happens with vagrant geese, such as Pink-footed Goose, which associate with Canada Geese near the breeding grounds, and follow the latter to their wintering grounds.
Many vagrant will keep flying until they hit a natural barrier, which for us often means the coast. Local hotspots like Plum Island, Cape Cod and the Islands are good places to find rarities.
The table below lists vagrants seen in Massachusetts in November over the past 10 years. They’re ordered by frequency, with the most common at the top. For example, Rufous Hummingbird has been seen in November in six of the last 10 years, with the most recent November sighting being in 2016.
|SPECIES||# Years||MOST RECENT||2017?|
|American White Pelican||3||2015|
|Tropical / Couch's Kingbird||1||2010|