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?