What is this strange noise?

June 11, 2008 2:27 PM

What is this strange, seemingly bird-related noise?

On a few occasions during the night last summer, I heard a strange, low-pitched noise at rhythmic intervals from the courtyard window of my apartment in Montréal, Canada. At first, it seemed like a percussive sound, as if someone was hitting a large plastic trash bin. I was intrigued by its rhythmic regularity, but overall it did not appear to be caused by a human, and I could not identify the precise nature of the sound. I don't remember this noise occuring during the day.

A few days ago, I heard the noise again and I managed to capture audibly once the intriguing sound. It appears to be linked to another obvious bird noise, an unpleasant bird screech (coming from an owl? A bat?). The pattern seemed to approximate to eight or so instances of the solo screech, one instance of the intriguing low-pitched sound in synch with another screech, and repeat.

Can you positively identify the nature of the two sounds?
Is it possible the two noises are generated by one bird?

Thanks!

posted by jchgf to science & nature (13 answers total)

Are you positive it's a bird? Sounds like a possum to me.
posted by mudpuppie at 2:36 PM on June 11, 2008

Yeah it sounds like a chipmunk/squirrel sort of noise to me, the sort of high-pitched cheep.
posted by jessamyn at 2:42 PM on June 11, 2008

I would guess the high-pitched screech comes from some sort of bird, but to be honest, I have no conclusive idea what it might be. The sound sometimes seem to hover above my apartment, but this may be due to tricky acoustics in my courtyard.

I have no idea what the lower-pitched sound is, but it does appear to be linked to the high-pitched screech, if only rythmically.

This is in an urban area of Montreal, so I ruled out any land animals in my mind, but I may be wrong.

On preview: okay, I can buy the high-pitched cheep coming from a squirrel, but what about the lower "howl" in the last part of the video? There is a lower-pitched noise below the high-pitched cheep. A squirrel seems too small to generate a sound in these relatively low frequencies, and I would freak out if a squirrel made this noise when I offer them peanuts. Perhaps a raccoon?
posted by jchgf at 2:49 PM on June 11, 2008

The lower pitched noise is from a birds wing. I've often hear them from hummingbirds and diving swallows.
posted by sanka at 2:52 PM on June 11, 2008

The screech is a Common Nighthawk. The Wikipedia entry includes a soundfile.
posted by media_itoku at 3:08 PM on June 11, 2008

It's from a common nighthawk. The reason you hear it above your apartment is because they tend to live on gravel roofs. They eat bugs, so they're great birds to have around. Incidentally, the site linked has a song link to the left which, as you'll note, sounds like yours.
posted by lleachie at 3:08 PM on June 11, 2008

Ack, media_itoku, you beat me!!
posted by lleachie at 3:11 PM on June 11, 2008

Thank you media_itoku and lleachie, mystery solved!

From Wikipedia: The call is a short peet usually heard overhead. The male performs an aerial display during courtship, creating a booming sound near the end of a steep dive. The sound is produced by air rushing through the wingtips.
posted by jchgf at 3:16 PM on June 11, 2008

Nighthawks here in Canada make a similar sound, but they quite clearly say "beer".
posted by weapons-grade pandemonium at 3:40 PM on June 11, 2008

The booming sound of the nighthawk's wingtips after a steep dive can be heard and seen in daylight in this video at 0:19.
posted by jchgf at 3:44 PM on June 11, 2008

I've heard a Nighthawk many times and its call is never accompanied by the low bass sound in your recording . The low bass sound in the recording sounded like a Bullfrog or a Green Frog to me. Bullfrogs are very rhythmic and can be very loud. The recording I linked to does not do them much justice. Green frogs sound much more random, especially when there is more than one frog calling.
posted by 517 at 4:42 PM on June 11, 2008

Just to be clear, I agree that the high-pitched sound in the recording is a Nighthawk. I think the low-pitched sound is a frog that just happened to call at the same time.
posted by 517 at 4:44 PM on June 11, 2008

But it is accompanied by a "boom":

* The male Common Nighthawk has a dramatic booming display used during the breeding season. He flies around at a moderate height, then dives straight toward the ground. Somewhere just about two meters from the ground he turns upward. At the bottom of the dive he flexes his wings downward, and the air rushing through his wingtips makes a deep booming sound. The dives are directed at females, young nighthawks, intruders, and even people.

(sound file available at the link.)
posted by rtha at 5:39 PM on June 11, 2008