Sounds of Vaux's Swifts
by Bruce G. Marcot
All images and sound files on this page © Bruce
G. Marcot
Following are 19 sound spectrograms and linked sound files
of various vocalizations and wing sounds of a nesting colony of Vaux's
Swift (Chaetura vauxi) that I recorded over 28-30 June 2003 near
Portland, Oregon USA.
The Colony
The colony was nesting in the front chimney of my house, itself unusual,
as many sources cite chimney-nesting by this species to be rare or uncommon.
The nest included 8 eggs; Vaux's Swifts typically
produce 4 to 5 eggs (less commonly 3 to 7), leading me to speculate
that this was a joint nest. When the birds emerged in a foraging
flock, most active at dawn and dusk, I counted 8-10 individuals, so I presume
these were likely from two different pairs rather than a double-clutch
from one pair.
The Recordings
I taped these sounds by inserting up the flue a small but sensitive Sony
microphone taped to a short camera tripod. I used a Sony cassette
recorder (model TCS-60DV) 
set to VOR (recording automatically starts when sounds are present, and
ceases when sounds stop) over a period of 3 days. I started recording
the birds shortly after I first heard that the hatchlings were vocalizing.
I then transferred the sounds to computer and saved them first as standard
WAVE (.wav) files, by using the outstanding shareware program GoldWave
(GoldWave Inc.) sound editing software. I cleaned each
sound file of pops, hisses, and low-frequency and background noise, by
using pop/click, highpass, and noise filters, and then converted results
to the MP3 sound files linked to from the figures below.
I created the sound spectrogram images
by using the program Spectrogram
(Visualization Software LLC). Note in the following
images that both the x-axis (time in seconds) and y-axis (frequency in
Hz or cycles per second) may vary among the various sound files.
The Implications
As far as I can tell, these may be one of the first recordings made
and annotated for at least some of the sounds made by Vaux's Swifts within
a breeding colony. I cannot find descriptions of all of the individual
vocalizations I present here.
The Sounds of Vaux's Swifts
Click on each image to hear the sound (MP3 format)
Calls by groups and individuals:
Typical group call from the breeding colony.
Group calls occasionally attain a sort of
synchrony. This may be by chance, or may
have some group behavior implication.
I surmise that the wingbeats may synchronize so as to reduce overall
turbulence in the confined space of the chimney as it would in a
confined hollow tree where the species normally roosts and nests in the
forest.
Such wingbeat-synchrony to reduce turbulence likely also occurs in other
swarming species such as locusts in northern Africa.
A "screech call" by an individual swift.
The synchronized group call above seem to consist of several
birds all giving this call at the same time.
Perhaps synchronizing their calls helps the flock
attain a unity, as they do leave the roost, forage aerially,
and return to the roost more or less as a unit.
An individual swift giving the more typical call.
The first group call above may be a collection of these
individual calls, but not given in synchrony.
Another example of the typical individual call.
A slightly slower and softer version of the
individual call, perhaps given just within the nest.
The above individual then began giving this
variation of the call, very different than the
more agitated series.
More group calls, this time with wing beats as
the fledglings began testing their wings in the
cramped quarters of the chimney flue.
An "agitation call" issued by an individual.
This is one of the vocalizations not reported in
bird field guides or annotations for this species.
A variation of the agitation call given by an individual.
Also apparently not previously reported or recorded.
A medly of the typical call, plus song elements,
and wing beats, given by an individual.
An individual giving its typical call with
fluttering wing sounds added.
Songs by individuals:
A song given by an individual, twice.
To differentiate from another song type below,
I call this a "type 1 song."
Also a "type 1 song", probably a minor variation of the
above song. Note the stretched-out time axis.
A "type 2 song." Although not a "songbird" per se,
the Vaux's Swift does seem to have a few variants of
its calls and song types. This seems to be unreported.
A "type 3 song." This may be transitional between
the typical calls and the type 1 song, or a subsong.
Flight school:
An individual testing its wings.
More sustained wingbeats. Learning to fly.
More testing of the wings. Not much room
to test fly in a chimney flue!