Yes, that hairy woodpecker drumming on your gutters in the early morning is a nuisance, but to a hard-core birder it could not be considered a nemesis. That is a species that even an avid birder can’t find. Shawn Patrick Ouellette/Staff Photographer

Every hobby has slang and jargon that is often impenetrable to those who don’t share the hobby. Birding is no exception.

A nemesis bird is not the hairy woodpecker that pounds on your gutter early in the morning, but rather an uncommon or secretive bird species that a birder can’t ever seem to find. When a birder says she dipped on the white-faced Ibis reported at Scarborough Marsh, she means she could not find it.

If you find a rare bird, you have found a mega, or if it is really rare, a MEGA. There are other more colorful terms for such rare birds that can’t be printed in a family-friendly newspaper.

One of the most perplexing slang terms in the birding lexicon for the uninitiated is the Patagonia picnic table effect. This phrase is applicable to Maine this winter. Before I explain, we need to review a little birding history.

Birders often keep lists of birds they have seen or heard, with a life list containing all of the birds one has ever seen. There are many other variants: a year list, a Maine list, a North American list, a North American year list, a birds seen on Tuesdays list. You get the idea.

Any time people start compiling lists, a bit of competition may emerge. Some birders want to compile a longer list than their friends or other birders. Birders who avidly maintain their lists are called listers

This competitive birding or sport birding took off in the late 1960s. Jim Tucker, a lister from Texas, wanted to develop a way for other birders to compare their various list sizes. Thus was born the American Birding Association with its magazine, Birding, with articles on sites where rare birds could be found, birding techniques and list totals to allow birders to see how they stacked up against other listers. Hard-core competitive birding was launched.

In the 1970s, the holy grail for a North American lister was 700 life birds. Roughly 660 species of birds occur in North America every year. Some require trips to far-flung places like the Pribilof Islands for red-legged kittiwakes and parakeet auklets, Key West for black noddy and pelagic trips off both the Atlantic and Pacific for various shearwaters and storm-petrels. But with effort, getting to 660 species can be achieved. Breaking the 700 barrier means finding 40 species (MEGAs if you will) that normally don’t occur in North America.

For the competitive North American lister, southeastern Arizona, the Rio Grande Valley of Texas and south Florida offer rich diversity as well as higher chances for rarities than other parts of the continent. One must-visit area in southeast Arizona is the Patagonia Reserve, a property owned by The Nature Conservancy. It’s a delightful place that offers a great chance to see gray hawks and some uncommon hummingbirds.

In 1977, a few birders in the Patagonia area stopped at a roadside picnic table for a break. They were fortunate to discover a pair of rose-throated becards, a flycatcher relative not normally found in North America. MEGA sighting!

Other listers descended on this picnic table to add the becard to their life lists. Becards are secretive birds so it took some effort for birders to find them. In so doing, they saw other birds. Some of these were rarities: black-capped gnatcatcher, thick-billed kingbird, five-striped sparrow, yellow grosbeak.

So, this snowballing phenomenon in which a rare bird attracts many birders, who find yet more unusual birds, drawing yet more birders who find even more rare birds was termed the Patagonia Picnic Table Effect.

I’ll finish this story with a recent Maine example in the next column and take a skeptical look at the Patagonia Picnic Table Effect. In the meantime, here’s hoping you find a MEGA and don’t dip on any of the birds you chase.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu