Absent Birds

Today I received an email from Sarah:

Dear friends,I spent some time in Spring and early Summer bird watching at dusk as a part of a study to account for a rare bird. I didn’t see or hear the bird, which has a distinctive call. It made me think about recording something that is absent, or recording absence. I reached out to other bird watchers around the world who were listening at the same time as I, and here attached is a recording made in Missouri of the same, absent bird.(Thanks to Valerie Heemstra for the recording)Sarah