A Troglodytes Mystery

By Sam Fason

On December 31^st, 2011, I participated in the Granger Christmas Bird Count, whose circle includes the Granger Lake Area of northern Williamson and southern Bell Counties, about 50 miles northeast of my home in Austin, Texas. I was hoping to tack on a few birds to my year list and maybe find a few lifers.

We birded from first light, finding species including Short-eared Owl, Cackling Goose (a lifer), Snow Goose, Ross’s Goose, Greater White-fronted Goose (a four goose day in Central Texas is very difficult), Burrowing Owl, Lark Bunting, McCown’s Longspur, Lapland Longspur (also a lifer), Common Goldeneye (rare in central Texas), and the six Whooping Cranes that have called Granger Lake home this winter, just to name the highlights. All of the birders in Area 1 (the north half of the circle) met in the small town of Granger for lunch. We decided that it would be best to bird a small area of bottomland woodlands. In a drought year with western influx birds, usually common winter residents such as Pine Warbler, Blue-headed Vireo, and Golden-crowned Kinglet would be a priority to find. We headed to the Willis Creek Wildlife Management Area where a small, mowed trail runs along Willis Creek, which has carved out a small gorge some 10-12 feet below.

As we made our way down the trail, our group (comprising Chuck Sexton, Christian Walker, Barry Noret, Ken Williams, and me) did not see anything other than the usual suspects. It was at that moment Christian called, “Winter Wren.” The bird flew down to the creek bottom and disappeared. As we attempted to re-find it we heard a bizarre call: a mechanical “tt-tt-tt-tt,” almost insect like trill, which none of us had ever heard before. I recorded the call with my iPhone and we puzzled over the possibilities. We had nothing. It continued for a solid five minutes, and five stumped birders stood intently looking at the green briar tangle at the base of an oak tree where the trill was coming from. What the heck was this bird?

Just then the wren flew out onto a fallen log that stretched across the creek. It was the source of this bizarre trill call. We noted how dark the bird was, with a rich cinnamon throat and eyebrow, dark rufous-brown back, and dark sides. Not a typical Winter Wren. I thought to myself, “This can’t be a Winter Wren…wait…if it’s not a Winter Wren then it has to be…a PACIFIC WREN!”  Recently split from the Winter Wren complex, the Pacific Wren is a bird of the Pacific Northwest, southern Canadian Rockies, and California. If this bird were a Pacific Wren, it would be the first documented Texas record. It was time to start freaking out. I took at least 100 pictures of the bird, 80 of which caught sections of the bird creeping, mouse-like, along the bank and the log, obstructed by roots. Luckily, he sat out in the open on the log for a few seconds and I got some clear pictures and several recordings of the call. This was as good as accepted, right? 

Not quite.

The wren had us riding high for the rest of the day, and whether we were chasing a Say’s Phoebe or freeing an entangled Ring-billed Gull, the wren remained in the back of our minds. But the saga was just beginning to unfold.

Chuck, Christian, and I all made separate posts on TEXBIRDS (the Texas birding listserv), giving a detailed account of our observations. One problem, mentioned by several people, was that these species where not identifiable by plumage alone. Fantastic. Also, the call proved inconclusive to most, for both species give a variable, mechanical trill when agitated. So we had a possible Pacific Wren. More research was needed.

People were immediately split on the bird’s identity. There were those who passionately opposed the ID as Pacific Wren, saying the two species cannot be visually distinguished, as well as many people who agreed with the identification of Pacific Wren. Now, people have looked in west Texas Troglodytes wrens before, hoping for a Pacific Wren, only to find numbers of Winter Wrens. Also, numerous reports of Winter Wrens from Arizona and New Mexico have been accepted.

As far as plumage goes, this bird was a pretty textbook Pacific Wren. David Allen Sibley lists the major field marks of Pacific Wren:

“Pacific darker, more rufous, and less patterned; Pacific usually has throat almost as dark and richly-colored as breast vs. pale throat contrasting with brighter breast band; Pacific tends to have the pale eyebrow stripe tinged rust/orange; Pacific usually has breast unmarked or with a few faint bars; Pacific is dark, deep, chestnut-rufous."

Check, check, check, check. So why could this bird still be a Winter Wren? Variation. Textbook birds simply do not exist regularly. Yet several people believe that the birds ARE identifiable from field marks alone. For example, a very typical Winter Wren was found in California a year ago, identified as Winter Wren and accepted, with only photos. So why couldn’t we have a valid record, based only on photographs? Winter Wren is clearly identifiable by sight alone, why wasn’t Pacific? We had plenty of evidence. The dispute was whether or not the evidence was useful. Back to square one: seeing the bird in the field.

A week after we originally found the bird, Chuck, Randy Pinkston, and I were back out at Willis Creek, trying to get a good recording of the bird. We struck out on recordings, but the wren was still on the same fallen log. However, we came across a complication: 80 yards down the creek was a definite Winter Wren. And it was singing. And interacting with the possible Pacific Wren. And the Pacific Wren only called when the Winter Wren called. Well, drat. All of our recordings from the day, despite being of poor quality, are a muddled mess. This explained Barry Noret’s recordings from the previous day of a Winter-sounding Wren downstream. Back to researching.

The second time I viewed the bird, I also realized the description of the call notes of the bird were not particularly helpful. Winter Wren’s call note is described as “Song Sparrow–like” whereas the Pacific Wren call note is described as “Wilson’s Warbler-like.” I didn’t find these descriptions to match what I heard in the field. Neither of the birds sounded like their field guide call-note descriptions. I now think using such subjective terms as an identification technique can be unreliable.

After a week of looking at pictures and listening to recordings of Troglodytes wrens ad nauseum, Chuck and I agreed that if this bird was a Pacific Wren, it was a first winter bird of the subspecies Troglodytes pacificus salebrosus, which inhabits the Canadian Rockies, including Montana, Idaho, and parts of Eastern Washington. Our bird visually and vocally matched this subspecies well and salebrosus has been recorded in New Mexico, Arizona, and Colorado.

I decided to do a spectrogram analysis of the trill call I recorded on the CBC, and I received good news: the kHz (kilohertz) levels were roughly 6-8, as opposed to Winter Wren’s typical levels of 3-5 kHz. I had never been more certain this bird was a Pacific Wren.

  As time passed I learned more and more about Troglodytes wrens. Also, as time passed, the identification of the bird remained in question. But as I began to write my portion of the report to submit to the Texas Rare Birds Committee (TRBC), I received an email. On January 31^st, a month after we originally found the bird, Chuck Sexton wrote to say that he had gotten a great recording of the bird giving a perfect Winter Wren song. Great. Just great. 

This still didn’t necessarily convince me that the bird was a Winter Wren, but it left me dazed and confused. I was uncertain of the ID, in every respect. My spectrogram, at one point considered conclusive evidence, might as well have been another tawny orange feather on the bird: useless in identification until proven otherwise. Experts that originally agreed with me that it was a conclusive Pacific now were either dumbfounded, as I was, or were wholeheartedly convinced this bird was a definite Winter Wren. But this raised several questions: Can you identify ANY Troglodytes wren in Texas without hearing a song? Could any Winter/Pacific Troglodytes wren be identified ANYWHERE without a song? If Winter Wren plumage can vary to where it looks nearly identical to typical Pacific Wren, then can’t Pacific Wren plumage vary to the point of looking nearly identical to Winter Wren? In that case, was the California accepted Winter Wren actually a Winter Wren, or just a bizarre Pacific Wren?  WHAT ON EARTH IS THIS BIRD, AND WHY CAN’T IT CHOOSE A CONSISTANT IDENTITY????

Here is yet another possibility: what if this bird WAS a Pacific Wren and it had learned to mimic the song of the downstream Winter Wren? The bird appeared to be a first year, not likely to sing on wintering grounds. Perhaps it had been harassed enough by it’s downstream neighbor the Winter Wren that it had learned to mimic its song in order to establish dominance on its portion of the creek. This point is what I am currently researching. 

In addition to driving me to the brink of insanity, this wren experience has taught me a lot. A few of the things I have learned include:

• Birds vary a lot in plumage.
• Birds vary a lot in song.
• Birds vary a lot in everything, really.
• Birds, especially ones with difficult identifications, must be studied intently.
• Don’t overlook anything, and be VERY observant.
• Never be 100% positive about anything. Being positive is the step below stubbornness.
• Be open to other’s opinions. Sometimes, as crazy as they sound, they’re right.

I could fill up a whole post with this, but I won’t. Even though I probably won’t ever be able to look at a Winter or Pacific wren with out cringing or muttering under my breath, or be able to feel comfortable calling a Troglodytes wren in Central Texas (or anywhere in the overlap zone) ever again, and even though the bird we saw STILL hasn't been positively identified, and even though this bird has irritated me to the point where I dread any email entitled, “Pacific Wren development”, it has been a remarkable learning experience.

First state record or not, this has definitely made me a better birder. But the first state record sure would be nice.

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About the author: Sam Fason is a 15-year-old birder who lives in Austin, Texas. He has been birding for over 8 years, and is greatly influenced by Victor Emanuel, who made Sam want to pursue birding as a passion from the first time they met. Sam has birded in many  other states, including Colorado, California, Montana, Maine, and New York. He doesn't have a favorite bird, but he particularly likes alpine breeders such as rosy-finches and ptarmigan, in addition to warblers. Sam attended VENT's Camp Tejano in 2011 and is attending Camp Cascades this summer.

 

 

Comments

[Paul Clapham]

I didn't see anything about intergrades in your post. Maybe that's what you have there?

[charlie moores]

Whether you were able to ID the bird to species level or not this is a womderfully written article. Well done.

[Ted Lee Eubanks]

Great article, Sam. Keep it up. You'll get that state record before long.

[Jeffrey Gordon]

Congratulations on a wonderful post, Sam! And on a true learning experience. May you have many more, and may they more often than not break in the direction of state records.

Strong work, sir!

[Sam Fason]

Thanks everyone!! Really means a lot to me!
Also Paul, we researched the possibility of a hybrid, and we couldn't find any records of the species hybridizing. they're breeding ranges are for the most part not connected.

[jack C Kidd]

Great read Sam, almost like an unfinished symphony. I am so proud of you and your writing is supurb. I may be a little biased. Jack