Once in A Blue Moon

through the new scope

“Once in a blue moon”, an idiomatic expression used to describe the rarity of an event. A “blue moon” is a full moon, which occurs twice within the same month. The full moon on the 31st, will be the second full moon in the month of December and therefore a “blue moon.”

The first documented U.S. sighting of a Tigrisoma mexicanum or, in plain English, a Bare-throated Tiger-Heron, happened on December 21. The bird was first discovered by a couple of birders as they walked along a dike next to the World Birding Center headquarters at the Bentsen-Rio Grande State Park where it has now been seen fairly regularly each day (best in late afternoon). So, yes, after seeing the tiger-heron today (excellent looks while it foraged for food), we can now say that we have seen the bird “once in a blue moon”.

Bare-throated Tiger-Heron (photo: Rick Snider)

There are three species of Tigrisoma in the world: Rufescent, Fasciated and Bare-throated. All three tiger-herons are typically found south of the U.S. border, from Mexico to South America. Bare-throated are found in more open habitats than other Tigrisoma, like river and lake banks where it will find suitable prey such as fish, frogs or small rodents that come within reach of its bill. It is a solitary breeder, is not normally found in heron colonies nor to be feeding in the company of other colonial nesting birds.

Fortunately the birders each had their camera with them and captured photos to support their finding. The bird will no doubt be added to the ABA recordable checklist in due course. Top listers from around the country are just now starting to trickle in. In the meantime, we’re in a relatively select group of U.S. birders who will be able to record the bird on our ABA checklist when it is officially added. It didn’t hurt that the area the bird is being sighted is a mere ten-minute walk from our site. Darn handy. We’ve seen Bare-throated Tiger-Heron in Mexico and Costa Rica (and the Fasciated, too) so this wasn’t a life bird but, for us listers, it was a nice feather in our ABA cap.

Ahhhh. You non-birders might be asking yourself, “What is a lister?” Simply put it’s a birdwatcher that keeps track of his or her sightings on a list. Or multiple lists. We have to admit that we keep several life lists of all the birds we see. There were our county-by-county and statewide Wisconsin life lists when we lived in WI. Given the amount of time we’ve spent in Texas we now keep a statewide Texas life list. We kept a yard life list – birds seen in or from our yard. We still keep a yard list except that now our yard dynamics and habitats change as we move. Consequently our yard list has grown far more quickly than when our yard was static. We keep life lists defined by geographic regions – regions determined by the ABA and AOU. Then there is our annual list – total bird species seen (whether we've seen them before or not) within a given calendar year. On January 1 we’ll start our annual list again. To keep track of our sightings and keep them in correct taxonomic order, we use the current nomenclature and taxonomy in Clement’s system of taxonomy. We use a database listing program Tom built to record our various lists. Note: Once found, putting a check next to a bird's name may not always be so simple as avian taxonomy is always in a state of flux.

Some of our family and friends consider us to be “serious” listers but we’re here to tell you there are some folks far more intent on listing than us. Ultra serious listers aren’t so much birdwatchers as they are bird check-off collectors. For example these folks are never seen to drive less than 20 mph over the speed limit between birding destinations and still claim to ID a bird while speeding down an expressway. They will consider time spent observing or admiring a bird beyond that which is required to identify it as a waste. Typically they will take less than five minutes to eat a meal (never sitting down), start birding before dawn, never quit before dusk and will spend all non-working days avoiding family. They are loath to communicate with non-birders and will avoid any and all discussions of any other non-avian life forms unless it involves a bird (“Such and such bird is sitting in/on/next to such and such ______.” (fill in the blank with the name of the appropriate vegetation). They will stoically ignore any No Trespassing, Private Property or No Parking signs (unless a bird is perched on one).

We find such listers at odds with our preferred birding demeanor (passionate but stable). Sure we like to keep lists but not at the expense of enjoying our surroundings and the companionship of our birding friends. We surely enjoy sitting down to a meal lasting longer than five minutes (even during the day). And, we hardly ever speed. Much.

Most birdwatchers will keep a list of target birds – birds they’ve never seen before but would like to add to their life list. Some of these are birds have eluded detection for a long, long time and which everyone else, even non-birders, have managed to see. These are known as “nemesis” birds.

Barn Owl (photo: Tom Sykes)

One such nemesis bird for Tom has been the Barn Owl. In 2007 Tom found a Barn Owl in Costa Rica so it was no longer a quest to add one as a life bird, However, Tom has never seen one in the United States, or what birders refer to as an “ABA tick” or checkmark on an ABA region life list. There have been many, many close calls. There is nothing more upsetting to a birder than to arrive at a distant location only to have another birder say, “You just missed it!” or, to arrive at an area described as a “sure thing” where the bird is "always easily seen" by anyone and everyone, even blind people...and still not find it.

The day after Christmas while driving home from a movie and dinner, we took a side road near the RV park. Well after dark, and without binoculars, Tom spotted the silhouette of what appeared to be an owl perched on a power pole guy-wire, sitting low and close to the road. He managed to maneuver the truck’s headlights to shine on the bird. Could it be? The heart-shaped facial disc was distinctive. Finally, the elusive Barn Owl was no longer a nemesis bird! Much high-fiving ensued.


As an added bonus it turned out that Carol didn’t have the owl on her ABA life list either. However, as any birder knows, there are two well-worn adages about birding. First, once you find a nemesis bird you start seeing them everywhere. Sure enough, while out on the dike looking for the Bare-throated Tiger-Heron a few days later, what should fly into plain view? Of course. A Barn Owl. And the second adage? There will always be a next nemesis bird. Now...where can I go to find a Red-crowned Parrot?

Vermillion Flycatcher, a regular visitor outside our window
(photo: Tom Sykes)