There are only two kinds of birding mistakes: those I’ve made and those I have yet to make. Like all semi-experts, I am proud of my bird identification skills. But all it takes is a vacation to an unfamiliar place to reacquaint myself with humility.

A mid-December trip to the upper Texas coast provided me with ample chances to screw up, and I grabbed every opportunity. It reminded me of how much I take for granted while birding in Maine. The truth hit home while I was sorting through a bunch of shorebirds on a beach in Galveston. Willets and sanderlings were plentiful along the waterline. Higher up the beach, a cluster of small plovers roosted in the sand.

“Semipalmated plovers,” I declared. My wife, Sandi, questioned my judgment, which is routine. These were pale, with only a partial breast band. Semipalmated plovers are abundant in late summer as they migrate through Maine. Piping plovers are similar but frosty. They are endangered summer nesters on our southern beaches. I explained that these birds were not pale enough to be piping plovers, and that wintering birds are often sun-bleached in their offseason plumage, which is why these semipalmated plovers were paler than we were used to.

Wrong. As we prepared to drive away, Sandi hit me with the key question: “What color were the legs?” Drat. I didn’t even notice. Both Maine species have yellow legs. I take it for granted. However, there is a third plover that is similar in size and pattern. They are never seen in Maine, but they sure are in Texas. Snowy plovers have black legs. Sheepishly, I returned to the beach and looked at the legs. Black.

I’ve seen snowy plovers before, in Florida and Texas. I knew they were present. I knew what they looked like. I had succumbed to a rookie mistake. I assumed familiar field marks and leaped to a lazy conclusion.

It got worse.

I’ve seen many Caspian and royal terns in my life. They are rare visitors to Maine, but they are common winter residents in the southern states. The Caspian tern has a reddish bill; the royal tern’s bill is more orange. Can I ever remember which is which? No. They also can be distinguished by darkness under the wing tips, but I can never remember which one is darker. (It’s the Caspian tern.)

Greater and lesser scaup are subarctic breeding ducks that migrate through Maine. They are nearly identical. When flying, both have a white stripe along the trailing edge of the wing. The stripe is longer on the greater scaup — a fact that I can never seem to remember no matter how many times I’ve looked it up.

The marsh wren is common in Maine’s cattail wetlands. Its cousin, the sedge wren, is a rare Maine breeder. Both are numerous on their wintering grounds in the Texas refuges we explored. If only I could remember which one is more heavily streaked along its back. (It’s the sedge wren. The marsh wren is nearly identical, but it is darker and with a bolder eye stripe.) Once again, I knew what to look for. I just didn’t remember which was which.

Clapper and king rails inhabit marshes across the south. They are nearly identical, but, let’s see … there’s something about the color of the face being a little different. Hmmm, now what was that key difference? (King rails tend to be a little redder in the face, and the flanks are more heavily streaked.)

I share my setbacks for two reasons. First, winter is a good time for a little southern birding, and many Mainers end up in Dixie for vacations or visits with relatives. (Mainers know better than to visit in summer. That’s just crazy.) Up here, we don’t have to worry about the difference between boat-tailed grackles and great-tailed grackles, since they don’t occur in Maine. Even in the south, their ranges don’t overlap much. But they do in Texas. When planning a southern birding adventure, it pays to study up beforehand.

Second, even in Maine many of our identification challenges are between a pair of similar birds: hairy and downy woodpecker, greater and lesser yellowlegs, Cooper’s and sharp-shinned hawk … and many more. In every pairing there are just a couple of key field marks to look for that make the ID simpler. Experienced birders do it instinctively. I do it automatically in Maine, but take me out of my home state and I end up eating crow. Or was that raven?

Bob Duchesne serves as a Maine Audubon trustee and vice president of its Penobscot Valley Chapter. Bob developed the Maine Birding Trail, with information at mainebirdingtrail.com. Bob can be reached at duchesne@midmaine.com.