Rare birds sometimes too good to be true

As we approach the height of autumn migration, birders should be scouring their favorite haunts for rarities. Because most southward-migrating birds are doing so for the first time, they have a greater tendency to get lost. Birds that normally pass over us unseen in the night can be brought down by storms or exhaustion right into our yards. And hurricanes can drive tropical ocean-going birds onshore.

October and November are the best months to find unusual species in Virginia. The Eastern Shore is a good place to look, because wandering vagrants often follow coastlines and get stuck on peninsulas.

But some rare birds did not get lost, they escaped. In fact, each state has a committee that adjudicates rare sightings and determines whether to add them to the official state list. Birders generally follow these rulings in deciding whether to “count” a rare bird on their personal list. But birding runs on the honor system.

The most frequently reported escapees are exotic waterfowl, which many hobbyists collect on outdoor ponds from whence they may escape. For example, the White-cheeked Pintail is an attractive tropical duck that often escapes from waterfowl collections. One recently seen in North Carolina could have been blown in by Hurricane Florence, but its tame behavior and location at a county park pond suggest that it may be an escapee. Otherwise I’d have headed there immediately!

The provenance of some rarities is hotly debated, and usually the people who saw it are convinced it’s wild, while those who did not see it find reasons to question the sighting. Clues such as feather damage from being caged, or unusual molting patterns, may make the origin of an escapee clear. On the other hand, when the same species shows up as a vagrant in the same region, during migration, time after time, it is usually accepted as a wild bird. Barnacle Geese, which breed in Greenland alongside our Canada Geese, but normally migrate east to Europe, show up almost annually in the northeastern U.S. For years these sightings were ignored by birders because these attractive geese are also commonly raised by waterfowl collectors.

In some cases, origins get more complicated. European Goldfinches were introduced in New York in the late 1800s by misguided enthusiasts. They became common for awhile, breeding and spreading into Long Island and New Jersey, and are illustrated alongside our native birds in the early Peterson Field Guides. However, the population succumbed to inbreeding and had disappeared by the 1950s, so is no longer counted by birdwatchers. Today, European Goldfinches that show up periodically at bird feeders in Virginia and elsewhere could be recent escapees from illegal captivity as pets, or vagrants blown in by a storm from the long-established introduced population in the Caribbean, or they might even be descendants of a few escapees that recently started breeding near Chicago.

Regardless of origins, seeing beautiful, rare birds is a thrill and should motivate you to put down the remote and get your hiking boots on. Every vagrant bird has an interesting story to tell.

Cristol teaches in the Biology Department at the College of William and Mary and can be contacted at dacris@wm.edu. To discover local birding opportunities visit http://williamsburgbirdclub.org/

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