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Tag: Hutton’s Vireo

How Fast Is That Vireo Singing?

How Fast Is That Vireo Singing?

Gray Vireo, Rabbit Valley, Mesa Co., Colorado, May 2012 (copyright Andrew Spencer)

I can still remember the first time I heard a vireo “complex song”.  It was after completing a transect for Rocky Mountain Bird Observatory  in San Miguel county, Colorado, as I was walking through some pinyon-juniper forest, looking for things to record.  I found a singing Plumbeous Vireo, and set up to record it singing.  No sooner I had turned on the recorder, though, when it started belting out this crazy run-on jumbled song!  I was taken completely by surprise, not even knowing Plumbeous Vireos had it in them to sing so awesomely.

Since that day I’ve heard complex song from many vireo species, but it’s still something I don’t hear very often, and a treat whenever I do.  This type of vireo song is mentioned fairly extensively in BNA, often under different names.  For Bell’s and Black-capped Vireo it’s called “courtship song”, and said to be given when the male is closely associated with the female bird.  For other species, such as Plumbeous Vireo, it’s called “complex song”, and said to be given in a variety of circumstances.  In my experience, though, it’s most often given by agitated birds, either after playback, or after an encounter with another member of their species.   Occasionally a song that is either complex song, or possibly subsong, is heard from birds during fall migration as well.

Most vireo complex songs tend to follow a pattern, with song-like phrases mixed with high, squeaky notes.  There appears to be some variability, with a higher agitation rate correlating to fewer song-like notes, more high-pitched notes, a faster pace, and sometimes a longer strophe length.  The Solitary Vireo complex, Gray, Warbling, and Yellow-throated Vireos all fall into this broad pattern.  Hutton’s Vireo also seems to belong in this group, though like its primary song, its complex song is also atypical.

Black-capped and Bell’s Vireos seem to give more discrete complex songs, called courtship song in BNA for both these species.  In both species the complex song is reminiscent of their primary song, but quieter, faster, and more jumbled sounding, but without the long, continuous run-on character of the above group and without the incorporated high-pitched squeaky notes.  White-eyed Vireo may also fall into this group, though it’s song seems to have more call-like elements and is more run-on.

A third group, made up on Red-eyed and Black-whiskered (and presumably Philadelphia) Vireos seems to rarely give a complex song at all.  Indeed, BNA doesn’t mention such a vocalization for Philadelphia or Red-eyed Vireo, and only briefly for Black-whiskered.  What I’ve heard from Red-eyed sounded more like the complex songs of the first group than the second, but in general seem less well differentiated from the primary song.

Below are examples of complex songs for every species for which I could find recordings.  Needless to say, if any of you reading this have recordings of species not represented here, or more examples of any of these species, please let me know!

Plumbeous Vireo

Probably because I consider it the “default” vireo complex song I’m going to cover this species first.  All of the vireos of the Solitary Vireo complex sing similar complex songs; typically these are fast, jumbled series of song-like notes, call-like notes, and high-pitched squeaky notes.

Blue-headed Vireo

The complex song of the eastern representative of the Solitary Vireo complex sounds similar to Plumbeous Vireo, and there are perhaps more recordings of complex song from this species than any other.  In addition to the examples from xeno-canto below, the Macaulay Library has three cuts: ML#84774, 84775, and 100870.

Cassin’s Vireo

The complex song of this species is like the above two in broad details.  The only recording I was able to find was one at the Macaulay Library: ML#105665

Yellow-throated Vireo

There is remarkably little information on the complex song of Yellow-throated Vireo. Macaulay has two cuts (ML#164094 and ML#73885) of sounds tending towards complex song, and it seems like it would fall into the same mold as the Solitary Vireo group.

Gray Vireo

From the limited sample size of the complex song of this local western species it seems that it sings this vocalization with more distinct song-like notes, mixed with high-pitched squeaky notes, but without the harsh call-like notes of the Solitary Vireo complex.  BNA says of this vocalization “most frequently heard on breeding grounds (central Arizona and w. Texas), but also heard on wintering grounds in Big Bend region, Texas (JCB) and Sonora, Mexico.”

White-eyed Vireo

Of all the vireo species, the complex song of White-eyed Vireo is perhaps the most striking.  It is a remarkable series of run-on calls, mixing song-like elements, call-like elements, and things in between.  BNA calls this vocalization “rambling song”, and says “Rambling Song is produced by adult males in a variety of contexts and frequently by immature birds.”

Warbling Vireo

As if the song of this bird wasn’t complex enough already! The few times I’ve heard Warbling Vireo complex song it fell into the general mold of this vocalization type: song-like notes mixed with higher pitched squeaky notes. The examples I’ve heard don’t seem to mix in any call-like notes. BNA doesn’t even mention this song type for this species, and given the number of Warbling Vireos I’ve seen and heard and how rarely I’ve heard complex song from them I suspect this is a relatively rarely given vocalization.

Hutton’s Vireo

A somewhat atypical species of Vireo by North American standards, the complex song of Hutton’s Vireo falls into the same category.  Like the others above, however, it contains song-like elements and high-pitched squeaky notes.  Overall, though, it is a slower song than the other vireo species, and differs less from the primary song in this regard.  BNA makes no mention of complex song for Hutton’s Vireo.

Bell’s Vireo

BNA calls the complex song of Bell’s Vireo “courtship song”, and says that it is given when the male is in close proximity to the female. That, coupled with the distinctive nature of this vocalization (it tends to come in more discrete phrases without either the high-pitched squeaky notes or call-like notes given in other vireo complex songs) suggests that it falls into another sub-group of vireo complex songs.

Black-capped Vireo

Black-capped Vireo complex song tends more towards that of Bell’s Vireo than that of other vireo species, but seems to contain more calls and fewer song-like elements. It almost sounds like a mix between Bell’s and White-eyed Vireo fast songs. Like in Bell’s Vireo, BNA calls this vocalization “courtship song” and says it is mostly given when the male is in close proximity to the female bird.

Red-eyed Vireo

The closest I can find to a recordings of the complex song for this species are linked below.  I’ve heard other instances of complex song by Red-eyed Vireo that tend a bit more towards the Solitary Vireo type, but in general it seems that this species has more song-like notes in its complex song, few if any call-like notes, and fewer of the high-pitched squeaky notes.  Given how common this bird is, and how many recordings of it are available, I believe that complex song is very rarely given by this species.

Philadelphia Vireo, Two Buttes Reservoir, Colorado (copyright Glenn Walbek)
Other species

Now we get to the fun part of the blog post – what do we still need?  I have been completely unable to find any recordings of the complex song of either Philadelphia Vireo (BNA describes a faster, more complex vocalization, but I am not convinced that this is actually complex song) or Black-whiskered Vireo (BNA describes a complex song, and I would bet money that it would sound like Red-eyed Vireo).  And even the other vireo species don’t have their complex songs very well documented.  How much more jumbled and call filled does the fast song of Red-eyed Vireo get?  How about Yellow-throated Vireo?  These kinds of questions will take someone being out in the field at the right time and the right place, and having a mic to ready to get it on tape!

Murder Most Foul

Murder Most Foul

Eleventh of May, 2009, just before 11 AM: I was walking down the road in upper Carr Canyon in the Huachuca Mountains of Arizona, hoping to find something interesting to record.  A Dusky-capped Flycatcher was calling occasionally; some distant Yellow-eyed Juncos and Western Tanagers were singing; but the day was beginning to heat up, and bird activity was waning.  Near where I parked my car, I heard some quiet high-pitched squeals, but they didn’t seem to belong to anything in particular.  For a moment I got excited when a pair of Buff-breasted Flycatchers drove off a pair of Brown-headed Cowbirds that had been, I guessed, “casing the joint” — but this interaction was brief and quiet and I got none of it on tape; nor could I find the flycatchers’ nest.

A minute later, from back near my car, I noted that high-pitched squealing again.  Belatedly, I realized it sounded like nestlings.  Eager to record some begging calls, I headed for the sound, which was coming from near the top of a short oak, and turned on my microphone.

At first it just sounded like baby birds being fed:

Carr Canyon, AZ, 5/11/2009.
Carr Canyon, AZ, 5/11/2009.

But soon it became clear that something else was going on.  There was more activity in the tree than you’d expect from parents feeding nestlings — at least two or three birds were fluttering agitatedly in the crown, but I couldn’t see what kind they were, or what exactly they were doing.  It started to sound less like begging calls and more like distress calls:

Same as above.
Same as above.

And then, suddenly, a large dark bird took off from the tree with something dangling from its bill.  Behind it came a smaller bird in hot pursuit:

Same as above.
Same as above.

The birds landed in the open for a moment, long enough for me to see that the nest robber was a male Brown-headed Cowbird, and the frantic parent a Hutton’s Vireo.  Then the cowbird took off with the nestling and the Hutton’s went after it, far out of my sight.

But the squealing at the nest continued.  After a moment I risked walking towards it, and discovered the female cowbird pecking furiously at the contents of the nest, while another Hutton’s Vireo, or the same one, flitted around it and scolded it ineffectually:

Hutton's Vireo adult scolds and nestling distress calls during predation by Brown-headed Cowbird.  Same recording as above.
Hutton's Vireo adult scolds and nestling distress calls during nest predation by Brown-headed Cowbird. Same recording as above.

Within a couple of minutes, the squeals stopped, and I could see the female cowbird eating something out of the nest.  After another minute she fled the scene, leaving the adult vireo alone with the ruined nest, and me as a witness to a particularly brutal version of a very rare event.

It has long been known that Brown-headed Cowbirds will occasionally destroy the eggs of their host species instead of parasitizing the nest.  It is rarer for cowbirds to attack nests after the eggs have hatched, but even so, the removal of nestlings by cowbirds has been documented one or two dozen times in the literature.  In some of these cases, the cowbirds have been seen to eat the nestlings.  However, the vast majority of all such attacks have involved solo females.  In only two or three cases has nest predation involving male cowbirds ever been documented (see Igl 2003 and the references cited therein).

Why do cowbirds do this?  One fascinating line of thinking is the “mafia hypothesis,” which holds that cowbirds come back frequently to check on the eggs they have laid in other species’ nests — and if they find the cowbird egg has gone missing (presumably because the host parents have recognized it as an imposter and ejected it), the cowbirds destroy the nest in retaliation (Hoover & Robinson 2007).  By forcing the host parents to build a new nest, the cowbirds may be giving themselves another chance to parasitize it at a later date.

I can’t comment on the validity of the mafia hypothesis, but I can say that what I witnessed was fascinating, and a little disturbing — and yet another reason to follow up on odd, unidentified squeaks in the forest.