Oh Lisa, you asked a great question, even though you are bordering on the
sacrilegious. Only the most august bodies of ornithologists have the
privilege to do bird name changes (different committees in different
countries), and, although the change is "immediate" (in North America, as
soon as the AOU check-list or one of its supplements is published), it
often moves through the birding community much more slowly. There were
still a few people using "green heron" 10 years after "green-backed heron"
became the official common name of one of our bird species, and now those
few people can laugh at the rest of us, now that it's "green heron" again
(or will they start calling it "green-backed" now?). It sounds as if this
was done rather capriciously, but in fact it was called "green-backed" when
two species were combined, and they wanted an inclusive name for the new
entity, and it is now called "green" again because those two species, with
additional evidence and further deliberation, are again considered
separate. Whew. I think there was even a song about it.*

Whenever there has been publication of a new American Ornithologists' Union
checklist, there has typically been a spate of common-name changing, but I
think we have entered a period of relative stability, in which name changes
will be more a response to "splitting" and "lumping" (as outlined above for
green heron) than to arbitrary decisions. However, there is a committee
working on standardized English names for all the birds of the world, and
the work of that committee may ultimately change a few more American bird
names. For example, what we call "bank swallow" is called "sand martin" by
the English (and thus it's the English common name all over Eurasia). And
the skua/jaeger pair has already been mentioned. Hopefully someone will
decide that names such as "common black-headed gull" are a bit too
cumbersome, and some other species with the name "lesser black-headed gull"
or whatever will be changed to make both shorter and simpler.

Most plants and animals don't have "common names," by the way, but with the
realization that biodiversity should be made accessible to
nonprofessionals, there has been a real effort to generate English (and, I
suppose, French, Tagalog, Urdu, etc.) names for our species. I myself made
up common names for over 400 species of North American dragonflies some
years ago, and that list, with some modification, is now the "official"
list. It was one of the most enjoyable exercises I've ever pursued, by the
way.

Most birders accept these "official" name changes without too much
grumbling, but some are particularly disliked, e.g. common moorhen (we
liked common gallinule better). "American black oystercatcher" was another
one generated by the 1983 AOU checklist, and, although it was changed
quickly back to "black oystercatcher" in a succeeding supplement, some
people didn't see that and are still using the 3-word name in publications;
so it is with our evolving, revolving language.

Dennis Paulson

*"Well I don't give a damn about a green-backed heron......"