This is a follow-up to my earlier post “The Austin Bat Bridge”.
This post is mostly about bats. First, however, is a couple turtles I observed while on the Ann W. Richards Congress Avenue Bridge (i.e., the bat bridge).
Now to the main event: the bat report. In my earlier post, I expressed disappointment that the bats would not be around while I planned to be in Austin. The good news is that some stragglers were still living there.
On my first day in Austin, I walked across, around, and under both ends of the bridge and could hear a lot of squeaking noises coming from under the bridge. It must be much louder during the summer.
I went out again to observe the bridge as the sun was setting, hoping to see something. I was not the only one, though, as twenty, or so, people had the same idea at the north end of the bridge. As the light was fading, the bats came out, although I did not see a large, dark swarm. Instead, I saw a few bats flying around above me.
I took some pictures, but they waited until it was pretty dark to come out, so here’s the situation: I had to crank the ISO of my camera up to 1600. Translation: the sensor becomes more light sensitive, but it also increases the noise (graininess) in the image. In spite of the increased sensitivity, I was still having to use exposure times between 1/80 and 1/40 of a second at full aperture (the depth of field — the range of distances at which objects appear to be in focus — is very shallow at wide apertures). That shutter speed is pretty slow for a bat picture. You should take the above discussion as a warning that you are going to see out-of-focus bat blurs, rather than bats.
A closer look at the previous bat blur:
One more blur pair:
