Rufous Twistwing (Cnipodectes superrufus) wing noise and vocalizations

Twistwings (genus Cnipodectes) are a pair of largish flycatchers, called twistwings due to the modified shape of the outer primaries of the male birds. One of the species, Brownish Twistwing (Cnipodectes subbrunneus) is fairly widespread, being found from central Panama south through the Amazon basin. The other, Rufous Twistwing (Cnipodectes superrufus) was only recently (Lane et al., 2007) described, and has a much more restricted range and habitat.

Here I talk about recordings I made of the wing noise of Rufous Twistwing, and compare them to the wing noise of Brownish Twistwing. I also talk about some of the vocal behavior that I observed, though I have less to add in that department due to the excellent paper by Tobias. Hopefully the information I present here will help birders in locating this local and little known species in the future.

Wing Noise

The vocalizations of Rufous Twistwing were well documented in the paper by Tobias. (see link to the left), but the mechanically produced sounds made by the modified primaries is much less well known. Lane et al., 2007 says:

"Mechanical noises have been noted in both species of Cnipodectes. Hilty and Brown (1986: 483) note that C. subbrunneus 'can produce a very audible pr'r'r'r'r'r' in flight with wings.' This description is similar to mechanical sounds [Thomas Valqui] witnessed, performed by C. superrufus at Kirigueti. In response to playback, Valqui observed the bird approaching aggressively, making an accelerating and decelerating buzzing noise, while flying ~4 m off the ground. Although it was not clear what the source of the sound was (and it was not tape recorded), it seems likely that it was mechanical and produced by the wings..."
To my knowledge this is the only description of the wing noise of Rufous Twistwing, and other than the recordings below I know of no other cuts of this sound.

Most of my observations of Rufous Twistwing were made during one morning at a site in southeastern Peru, near the town of Iberia. Though I spent three and a half days in the area, other than the one morning I only heard a couple of other twistwings and didn't see any of them. For some reason, though, the morning I did find twistwings I found quite a few, and ended up extensively recording three birds.

While watching the first bird I found I observed the bird fly from one perch to another with slightly slower and deeper wing beats than normal flight, and produce a loud mechanical noise. Completely unprepared for this, I missed my opportunity to record this display sound. Luckily, a few minutes later, I managed to get most of another one of these display flights.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
This was the first wing noise I recorded from Rufous Twistwing, given naturally.


While making this sound both the wing beat rate of the bird, and the overall speed of the flying bird were slightly slower than I observed during normal flight. It would fly horizontally from one perch low (~1.5 meters) in the bamboo patch to another, ~15 meters away, whereupon it would sit there and not make any more noise.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
The first response to playback; the first second of the recording is off focus.



30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
The second response to playback; these wing noises followed by an extended series of calls.


The sound I recorded during these display flights is made up of two simultaneous or nearly simultaneous series of notes, both nasal, with the first less so, higher pitched and noisier, the second lower pitched and more nasal. These notes were at times also given separately, though this occured far more often in lower element than the higher.

The higher of the two elements is noisier (in the sense of having less clear harmonics and being raspier) than the lower one, and seems to more clearly be a mechanical noise. The lower element has much clearer harmonics, and whether this is a vocal sound produced in time with the mechanical upper element noise, or another mechanical sound is unknown to me for sure. This second element is the one I recorded being given in the middle of a calling bout, when the bird flew a very short distance from one perch to another.

The wings of Rufous Twistwing have a number of different modifications from a normal Tyrannid wing (read Lane et al., 2007 for details on all the modification; see also this photo, from the Neotropical Birds species account, linked on the left). How each of these modifications could be contributing to the sound I recorded is beyond my abilities to judge.

I did not see the bird making vocal noises during the flight displays, but neither was my view good enough to be sure that it wasn't. Since the wings of Rufous Twistwing have multiple different modifications it is possible, though, that different modifications could be producing different sounds during the same flight display.

Playback of the wing sound induced an immediate and aggressive response, first with another display flight, then with a slightly shorter display flight followed by a series of calls. Playback of the calls I recorded from this and other individuals also produced a strong response, but none as strong as playback of the wing noise.

Other than the first individual I heard giving the wing noise, I only heard a couple of very short single notes of the lower element from another bird. These were given during an aggressive calling bout in response to playback, during a short flight to another branch.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
Three notes of (potential) wing noise during a bout of calling (at 1.3-1.7s).


During "normal" flight the wings of the Rufous Twistwings I observed made slightly more noise than that of a bird of comparable size, with a very faint overtone of the sound produced during the flight display. Included below are a couple of examples of this.


Wing noise during "normal" flight, from the same bird giving the flight displays above.


Wing noise during "normal" flight, from a different bird than the one giving the displays above.

The wing noise produced by the Rufous Twistwings I recorded is (not surprisingly) quite like that of Brownish Twistwing. The four recordings I've been able to find of that species' display sound (the three from Macaulay, linked on the left, and one from Peter Boesman's Bird Songs of Peru collection) were all somewhat faster, and notably higher pitched (the greatest energy was concentrated ~5300Hz as opposed to ~4250Hz for Rufous) than that from Rufous Twistwing.


15-04-1995 Cana, Darien, Panama © Peter Boesman
Brownish Twistwing wing noise, courtesy of Peter Boesman. Note the significantly faster pace, higher pitch, and apparent lack of a second sound component.


Why the flight display of this species has been so rarely observed is a mystery to me. It is possible that since the sounds of even Brownish Twistwings are so poorly known that the wing displays have mostly been overlooked; if the bird giving this sound isn't seen I can see how it might not be connected to Rufous Twistwing. I don't know with what frequency this species or Brownish Twistwings give this display, but presumably it is associated with breeding, and times of year leading up to nesting would, in my opinion, probably be the best time to listen for this sound.

Vocalizations

The vocal sounds I recorded from Rufous Twistwings at Oceania mostly fell into the three vocalization types as outline in Tobias et al., 2008 (see link to the left). However, while that paper described "vocalization #1" as the most frequently given, I heard "vocalization #3" far more often. I also heard a far wider variation in vocalization #1 than described there.

What Tobias calls "vocalization #3", or short call, was the most frequently heard spontaneously given vocalization while I was at Oceania; all the birds I found were initially giving this call.


"Vocalization #3", from the same bird giving the flight displays above.

When giving vocalization #3 spontaneously, the vocalizing bird would call at a regular interval, which varied from every 7-8 seconds to every 15 seconds. The calling bouts I heard usually only lasted 1-2 minutes before the bird went silent.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
"Vocalization #3", one example each from three different birds.


"Vocalization #3", from the same bird giving the recordings below.

"Vocalization #1" was heard much less often, once in response to playback, and later during an aggressive bout of counter-calling between two birds. The number of notes, and the speed of delivery, during bouts of vocalization #1 varied widely, as did the variety of notes.

The most common variation of vocalization #1 that I heard started with a few hesitant, relatively widely spaces notes, followed by a rapid chatter that accelerated slightly, and lasted ~2 seconds.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
"Vocalization #1", the most common variation of the call I heard.


During especially aggressive series of calls (most of which occurred during dispute between two neighboring birds) I also recorded a wider variety of note types than mentioned in Tobias et al. for vocalization #1. The include more mellow notes with fewer harmonics, longer notes, and both upslurred and overslurred notes. It appears that during some aggressive interactions (whether with conspecifics or in response to playback) the variety of noises that a Rufous Twistwing can make is more varied than previously known.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
"Vocalization #1", showing a variety of note types.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
"Vocalization #1", a longer example from the cut above, showing variation in this call type.


Interestingly, playback of both vocalization #s 1 and 3, while getting a response from the target bird, did not garner as strong a response as my recording of wing noise, nor as strong a response as during the intraspecific interaction between two birds. Playback of vocalization #1 to the first bird resulted in the bird approaching me quickly and giving vocalization #3. Playback of vocalization #1 to a second bird (which was already giving those calls) resulted in a quick approach and a bout of vocalization #1, two brief wing noises, and an extended series of vocalization #3.


30-10-2009 Oceania, Madre de Dios, Peru © Andrew Spencer
"Vocalization #1", different bird than the one above, showing a lot of variation in note type. Note especially the wing noise at 6.1s, and the more mellow notes around 9s.


I never heard "vocalization #2", and playback of ML#124452 to birds I observed at Oceania produced no noticeable response. I also played that cut speculatively throughout the bamboo patch, both before and after I recorded the birds I had found, with no response.

I think that it is possible that Rufous Twistwings have been overlooked in the past due to an unfamiliarity of many birders with vocalization #3. Until the recent publication of the paper by Tobias et al. that call was unknown, and even now almost all the recordings of Rufous Twistwing are of vocalization #1. Given the frequency that I heard vocalization #3 I think that listening for it in bamboo patches in southeastern Peru would be a good way to search for this species.

References

Lane, D. F., G. P. Servat, T. Valqui, & F. R. Lambert. 2007. A distinctive new species of Cnipodectes tyrant flycatcher (Passeriformes: Tyrannidae: Cnipodectes) from southeastern Peru. Auk 124:762-772.

Lebbin, Daniel J. 2009.Rufous Twistwing (Cnipodectes superrufus), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=31406

Tobias, J. A., D. J. Lebbin, A. Aleixo, M. J. Andersen, P. A. Hosner, E. Guilherme, and N. Seddon. 2008. Distribution, behavior, and conservation status of the Rufous Twistwing Cnipodectes superrufus. Wilson Journal of Ornithology 120:38-49.