Ovenbirds Flipping Out

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Ovenbird. Lesser Slave Lake Bird Observatory, Alberta

Stop and think of the most easily distinguished and most monotonous songsters in the Canadian woods during the breeding season. “Teacher – Teacher – Teacher – Teacher – Teacher!” Although Ovenbirds are familiar and welcome singers, they seem to be in a vocal class of their own when it comes to predictability and stereotype of song.

Ok, now throw that conception of the Ovenbird out the window. Stop what you’re doing and quickly grab your Sibley smartphone app and dial up Ovenbird song “flight song_MI”, listen to the Stokes Ovenbird track at about the 20 second mark, or listen here.

Now – raise your hand if you’ve heard this before! I will be honest. When reviewing bird vocalisations in preparation for the breeding season, I skip over species like the serene, predictable Ovenbird to save time. But this year, I listened. When this complex vocalisation played I think I actually yelled (to myself in the car) “you have to be kidding me!” I had never heard anything remotely similar to this in the field. I played it again to make sure there wasn’t an error in the track.

The Sibley app describes this vocalisation as a “complex flight song that is often heard at night over wooded areas”. The Birds of North America account (Porneluzi et al., 2011) describes this vocalisation as follows:

The Attenuated Song is highly variable, ranging in length from 4 to 7 s. It is characteristically introduced by a series of whink notes and a ple-bleep vocalization. This initial part of the song is followed by a rambling section which includes 1 or more chip notes and sometimes additional primary song phrases or ple-bleep notes. Of the 33 instances when Lein (1981) recorded the attenuated song, 30 involved interactions between conspecifics. Twelve of 17 records occurred during male-female interactions involving chases, aggressive attacks by the male, or copulation attempts. Also used in aerial chases during territorial encounters between males.

The Flight Song is a version of the Attenuated Song, but given as part of an aerial display. It is most commonly given at twilight, but also at dawn. Lein (1981) described the display as follows: “The male was initially perched in a tree, usually at the height of the subcanopy. The male gave a series of soft chip calls while perched. The rate of delivery of these calls accelerated until the bird took flight and climbed 3–15 m above the treetops. He then flew in a hovering flight with spread wings and tail while delivering the song. The flight appeared to be labored and the bird sometimes circled as it sang. Immediately upon completion of the song the bird dropped back into the woods.” The structure of this song varies within and among individuals, mostly in the last part.

In dozens of hours of nocturnal, crepuscular and diurnal listening surveys in habitat known to be densely stocked with Ovenbirds I have yet to hear this vocalisation. In retrospect, given the first law of thermodynamics, it should have been obvious that this seemingly monotonous species was hiding something up its sleeve (up its voice box?). In fact, the Ovenbird has much more up its voice box as well, including muted songs and 13 additional calls give by males and females (Porneluzi et al., 2011):

Male
soft sip —a high-pitched call;
chep —a loud call, also described as tchuck and chirp (Hann 1937);
pink —a sharp, explosive-sounding vocalization;
seep —used in conjunction with ple-bleep and incomplete songs;
ple-bleep —two-note vocalization that’s a regular part of the introduction of the flight song;
whink —a buzzy or nasal-sounding vocalization;
whip —a very soft call.
Female
high tsip —produces a saw tooth pattern on a sonograph;
tsip series—a series of 6–10 high tsip notes, occurring at 0.1 s intervals;
chep —resembles the male chep vocalization;
chitter—similar to the tsip series, sounds like continuous twittering,
whimper—a very soft vocalization, audible only within 5–10 m of female;
seet—notes have the highest peak frequency of all calls and each note varies from the other on the sonograph.

In the mad dash of Breeding Bird Survey routes…in the brief cross-sections of time we slice for point count surveys…in the flurry of marking four-letter codes in our fieldbooks (…COYE, OVEN, AMRE…)…we race to achieve species identification and then move on. In doing so we boil birds down to very simplistic archetypes of their true natures. And it is nice to be surprised by their complexity.

References
Porneluzi, Paul, M. A. Van Horn and T.M. Donovan. 2011. Ovenbird (Seiurus aurocapilla), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/088
doi:10.2173/bna.88

 

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