Troglodytidae - Birds Who Creep into Holes, Part 2

The Wren Family (Troglodytidae from the Latin, “one who creeps into holes”) consists of busy little brown birds who always seem to be up to something. Generally, they are not much to look at, but what wrens lack in the flashiness of their plumage, they more than make up for in the gaudiness of their songs.

With one exception, our local wrens are more likely to be seen than heard. The exception is the House Wren, and even he tends to stay hidden. While many birds will sing their song from a prominent perch, the House Wren usually stays hidden in the foliage. His incessant activity and abiding curiosity in our open backyards, allows us to see him as he hurries about his business.

There are four representatives of the Wren Family in southeastern Vermont: House Wren, Winter Wren, Carolina Wren, and Marsh Wren.

Carolina Wrens are the largest of our local wrens (5 3/4 inches) and also the most handsome, with a buffy breast and prominent while eye stripe. As their name implies, they are a southern species, though they have been extending their range northward. They have been nesting for a number of years in Brattleboro and the Connecticut River valley. They are moving up the river valleys; there have been nesting pairs in Williamsville and South Newfane for several years. They stay the winter (they are regulars on the Christmas Count) unless severe weathers causes them to withdraw southwards or does them in.

Marsh Wrens (size about 5 inches), inhabit reedy marshes. They epitomize the elusiveness of wrens. They are far more likely to be heard than seen. Occasionally, if you are lucky and very patient, you might see a Marsh Wren singing in the open, or glimpse one as it pops up to investigate some noise. But more often you will get only fleeting impressions as it flits furtively through the dense marshes.

The songs of the Carolina Wren and the Marsh Wren have been extensively studied by scientists, and the results are astounding. Male Marsh Wrens have a song repertoire that averages about 50 songs per male in the East, about 150 in the West. One western Marsh Wren had 219 songs in its repertoire. “A male will cycle from one song to the next, moving through his repertoire in a fairly predictable fashion. Neighboring males often will engage in matched counter-singing. The two males will follow the same song series, one of them offering the song just given by his rival. The function of the counter-singing among Marsh Wrens is unknown, but observers have suggested that it may ‘normalize’ relationships between territorial neighbors, possibly reducing active aggression and the injuries that result from it.” (Sibley in “Bird Life”)

Carolina Wrens have smaller repertoires (about 32 songs per male) and use them differently. They sing the same song over and over - up to 250 times, then switch to another song. When encountering other territorial males, they switch songs more often. “Researchers hypothesize that matched counter-singing in the Carolina Wren calibrates the distance between two rival males. Since both males know how each song should sound, they can determine how far away their rival is by how degraded (by trees, brush, and incidental noise) his song sounds. Thus if a male gives a song known by his neighbor, he very clearly announces his presence and location on his territory, possibly preventing territorial incursions.” (Sibley)

With such large song repertoires, how does one go about learning the songs? The Marsh Wren is the easier of the two. It has a “wren” quality to it: bubbly and rattled, but reedy. When you hear a wren, or a rather long, complex song, in a dense marsh (for example, the marshes in the Retreat Meadows or Herrick’s Cove), it is almost certain that you are hearing a Marsh Wren. The Carolina Wren is more difficult. It is very loud and clear-noted. Kaufmann describes the Carolina Wren’s song as “rollicking, full-toned chant, ‘liberty-liberty-liberty-whew.’ Many variations.”

Since both the Marsh Wren and Carolina Wren are members of the Family “one who creeps into holes,” they both nest in cavities, of a sort.

The Carolina Wren is “flexible” about the cavity in which it nests. It will choose a natural hollow in a tree or stump, an old woodpecker hole, the middle of a brush pile, a nest box, the crevice in a building, the shelf in a garage, and any other spot that may catch its fancy. The nest is often domed with a side entrance. Twigs, leaves, weeds, and many other material go into the bulky mass that makes up his home.

A cavity for a Marsh Wren is a bit more problematic. There are no logs, stumps, woodpecker holes, or convenient nest boxes dangling from branches in a marsh, and cattails, bulrushes, and marsh grasses hardly provide holes to be crept into. So what does the Marsh Wren do?

A few summers ago, I kayaked in the marshy mouth of the Missisquoi River in northern Vermont. Marsh Wrens were occasionally popping above the marsh grasses singing their reedy wren song, then dropping back down. I drifted with the desultory current along the edge of the grasses, catching glimpses of the wren as he popped here and there, hoping that he might give away his nest location. Searching through the thick, reedy vegetation, I looked for some anomaly. I found an oval brown mass, like the boil on a tree trunk, except this was attached to a cattail. Through binoculars I could see that it was intricately woven out of old wet grass and assorted marsh detritus. The wren continued popping here and there. One of his pops landed him on the top of the oval mass of grasses, a hop put him halfway down the side of the mass, and then he disappeared into the side of the mass. Inside, I later learned (from books - not from destructive investigation) the Marsh Wren’s artificial cavity was lined with fine grass, plant down, and feathers.

In the course of my drifting, I found two more Marsh Wren nests near the edge of the reeds. The homesteaders who had built these cozy nests vociferously protested my near invasion of their claim, but stayed hidden from sight.

Troglodytes - that avian family of the Wrens, the family of birds who creep into holes - always provide entertaining moments. Perhaps that’s why they are my favorite birds.

Good Birding!

Troglodytidae - Birds Who Creep into Holes, Part 1

During our long morning of birding in Somerset, we heard Winter Wrens in every dark wood and tangled spruce thicket. The long, complex song of musical trills tumbled through the dank forests, so many notes falling over one another that you have to wonder how the small lungs can contain so much air to sustain the sound for so long.

By noon, the mountain clouds were finally being dissipated and patches of sun light filtered through the thick canopy of leaves. Even so, most of the forest was still in dark shadow; undergrowth was limited only to the most shade tolerant species. When a Winter Wren burst into song only a few feet from the trail, we went in search, approaching from different directions in an effort to surround the sound. He sang - first to my left - then to my right - then behind me - in front of me - to my left again. Somehow moving about, dematerializing and rematerializing. Or using some elaborate system of audio speakers, flipping switches from one to another to the next. Or with a ventriloquism that makes Charlie McCarthy or Lambchop look like real dummies.

Finally, on a thin twisted branch of a fallen hemlock, I saw a brown nodule quivering. The Winter Wren tilted its small body upward. Its stubby tail was cocked high. Its upturned beak shivered. Its throat quavered. The energy pulsed through its wings as it teetered and bobbed through its song. Note after note tumbled forth. I whispered reference marks to my companion, and then we both watched as this secretive little bird of dense woods poured forth his big song, from one perch after another - pausing only occasionally to do a quick foray beneath the log - or perhaps to check on a mate or nestling.

Finally we left him to his long, busy, contralto aria. Picking our way back to the trail we murmured something about a favorite bird.

The Winter Wren is a troglodyte. Troglodyte applied to a person suggests one with the character of a savage cave dweller. Troglodyte - or more specifically, “Troglodytidae” - is the Family name for the “Wrens” and derives from the Latin for “one who crawls into holes.” Most wrens, as a Family, use enclosed spaces for their nesting sites, such as tree cavities, holes among rocks, sometimes holes in buildings, or they build their own cavities, typically globular masses with side entrances.

As Kenn Kaufmann puts it, wrens are busy little brown birds, creeping about in thickets or peering out furtively from brush piles. They always appear to be up to something. That is of course, if you are able to see them. The generally drab nature of the wrens’ plumage is counterbalanced by their superb singing skills. There are about 70 species of wren, most of them in the tropics, and all but the Winter Wren (known in Europe simply at the Wren) are limited to the Western Hemisphere. Our Winter Wren sings a rich and complicated melody. But imagine - in the tropics one can find the Flutist Wren, Nightingale Wren, and Musician Wren!

The Winter Wren epitomizes the troglodyte nature of the Wren Family. Its full scientific name (Family, Genus, species) is “Troglodytidae Troglodytes troglodytes,” which might be translated as “one who creeps into holes, one who creeps into holes, one who creeps into holes.” At about 4 inches, the dark Winter Wren is the smallest of our local wrens - a “stub-tailed gnome that haunts northern evergreen forests in summer ... hard to see, creeping like a rodent under fallen logs, through dense thickets, along streambanks.” (Kaufmann) In spite of its name, most leave our area for the winter months, although a neighbor often has had a Winter Wren wintering in the cavities of his woodpile, and one winter thaw day, I spotted one disappearing into a hole in a sandy bank.

 In addition to the Winter Wren, three other members of “Family Troglodytidae” are found in our neighborhood of southeastern Vermont: House Wren, Carolina Wren, and Marsh Wren.

The closest relative to the Winter Wren is the slightly larger (4 ½ inches) and familiar backyard bird, the House Wren (Troglodytes aedon). Very early in the European settlement of North America, it received its common name because of its tendency to nest around homes or in birdhouses. The House Wren is an active and inquisitive bundle of energy. Its short tail held high, it bounces about, pausing often to sing its rich bubbling song.

Sibley describes vocalization as the wren’s primary defense mechanism (no “Speak softly but carry a big stick” strategy for this Family). If loquacity doesn’t work, the wren will employ physical confrontation. Last week, I watched a House Wren in my backyard drive away several intruding cowbirds. After the first brood had fledged, the House Wren had gone to work on another nest. The cowbirds were looking for a nest to parasitize or to rob. The House Wrens were having none of that. When the Brown-headed Cowbird - House Wren confrontation was over, I walked over to the nest box. The female looked out at me; she had sat tight on her nest while her mate defended his territorial prerogatives.

As much entertainment value as the House Wrens provide in my backyard, I have mixed feelings about them. They are so aggressive in defending their territory that they will often puncture the eggs of other birds nesting nearby (including those of other House Wrens). They are not feeding on the eggs, just destroying them, in an effort to protect their neighborhood and perhaps confuse predators with abandoned nests.

A few years ago, I watched a serious neighborhood dispute between House Wrens and Black-capped Chickadees. Several times the chickadees were driven out of boxes in which they were attempting to nest. I thought the dispute had finally been resolved when the wrens were busy caring for nestlings and the chickadees were lining yet another box with moss. But after the wren-cowbird confrontation, I checked the box where the chickadees were most recently trying to nest. The cup of soft moss was empty - no eggs, no nestlings, and no adult chickadees. When I closed the box and walked back to the house, the House Wren, hidden somewhere among the leaves of the apple tree, rollicked his song, proclaiming his dominance.

Like his close cousin, the Winter Wren, you may not be able to see him, but you always know when he’s in the neighborhood.

Good Birding!