NOVEMBER IS RARITY MONTH!

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:

  1. 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.
  2. 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.
  3. 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.
  4. 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# YearsMOST RECENT2017?
Rufous Hummingbird62016
Western Tanager62016
Ash-throated Flycatcher62016
Cave Swallow62015
Painted Bunting42016
Western Kingbird42015
Yellow-headed Blackbird42014
Scissor-tailed Flycatcher42013
Sedge Wren32016
Mountain Bluebird32016
Harris's Sparrow32016
Ross's Goose32015
American White Pelican32015
American Avocet32015
Black-chinned Hummingbird32015
Gyrfalcon32011
White-winged Dove22916
Bell's Vireo22016
Pink-footed Goose22015YES
Tufted Duck22015
Brown Booby22015
Townsend's Solitaire22015
Macgillivray's Warbler22015
Eared Grebe22014
Gray Jay22014
Audubon's Warbler22014
Western Grebe22012
Allen's Hummingbird22012
LeConte's Sparrow22012
Henslow's Sparrow22011
Tundra Swan22010
Boreal Chickadee22010
Yellow Rail12016
Elegant Tern12016
Hammond's Flycatcher12016
Purple Gallinule12015
Common Ground-Dove12015
Smith's Longspur12014
Brown Pelican12012
Little Egret12012
White Ibis12012
Northern Lapwing12012
Varied Thrush12012
Barnacle Goose12011YES
Cassin's Kingbird12011
Tropical / Couch's Kingbird12010
Fork-tailed Flycatcher12010
Black-headed Grosbeak12010
Wood Stork12009
Mew Gull12009
Townsend's Warbler12009
Lark Bunting12009
Black-tailed Gull12008
Broad-billed Hummingbird12008
2017-11-03T11:34:06+00:00