Population sampling.....or something.

I'm reading "The Moon: A Biography" by David Whitehouse. Pretty good
book. The timing couldn't be more fortuitous.....full moon (or very
close to it) tonight. Reminded me that I haven't looked at the moon
through my spotting scope for quite some time. So, I got it out on the
front stoop and focused in.

Took a few seconds to focus and let my eye adjust to the change in
light intensity and was just starting to spot a few familiar landmarks
when something zoomed across the face of the moon. Cool, I thought, a
bird. And then another one went by. Wow. A couple more flew by in
the next minute or so.....higher up.....took longer to make the
transit. Not birds. Bats! Twenty minutes, twenty bats.

Hm......

I don't recall how many minutes (degrees?) of arc the moon covers in
the sky (haven't run across it in this book), but it's a very small
piece of the whole. Seems to me that there must be an awful lot of
bats up there (and most of them very high, judging by their apparent
size in the scope for me to see that many in that short a time.

Anyone here know how to extract any useful information from this?

Wolfgang

Wolfgang