Friday, September 24, 2010

A Batty Sunset

Melinda had a night off tonight, and one of the things we always wanted to do one summer evening is to head down to Campbell Avenue where it crosses the Rillito River (more properly a wash this time of year). We don't get the local paper, but we found from the Internet that the annual Bat Fest was held September 11th this year, so we missed that. The colony of Mexican Free-tailed Bats migrate south of the border for the Winter, so we needed to go soon. This evening was perfectly clear and mild, so it was time to pull the trigger!

We chose to take one of the access ramps down to the river bed and as soon as we were under the bridge, we saw the signs - bat poop! You can see the accumulation in less than a week, since the rain we got last weekend had the Rillito flowing. Looking up you couldn't see them in the dark crevasses of the bridge structure, but you could hear them (Melinda thought it was a hummingbird twittering sound), and the camera flash illuminated them as they prepared for a night's feeding. I recall reading that this colony has a few tens of thousands of inhabitants, and since we live less than 2 miles away, the bats that frequent our neighborhood likely call this bridge home. They are certainly welcome visitors - the 1.5 million bat colony in Austin Texas is estimated to consume 5 to 15 tons of insects every evening! They certainly contribute to the lack of summer pests in the Tucson area.

Finally the sun set, twilight fell, and Jupiter, a couple days past opposition (the point opposite the sun as seen from Earth), popped into visibility low over the Rincon Mountains. Melinda and I picked our positions, not knowing quite what to expect, since this was our first time attending what is, of course, a daily event.

And then suddenly the unheard signal was sent and the hordes were released, filling the air with swift-moving fluttering shapes. It was dark enough that it was difficult to freeze their motion without using the flash, but clouds of them were seen in silhouette against the twilight glow in the west. The display seemingly went on for many minutes, and I had time to experiment with different methods of capturing them on camera, most not very successfully. We'll definitely be back to experience it and try again to capture better images. And as I pointed out to Melinda - it was about the cheapest "date" you can have in Tucson!

The story even has an astronomical ending! After getting back to the car, we thought for a couple minutes about dinner. We headed the couple miles over to Red Lobster. Parking, we had a perfect view of the rising moon split by Thimble Peak. Of course, the camera was stowed, but in 30 seconds I'd reassembled with telephoto lens, guessed the right exposure and still caught it with a bit of the thimble in silhouette. Picking a different parking spot, we would have missed it all together. A perfect ending for a happenstance evening!

1 comment:

David A. Harvey said...

Nicely seen! I went to "Bat night" on the eleventh - some advice - don't bother. Way to many people on bat night. They scare the bats and they only dribble out because of all the flashlights and camera flashes and human generated noise. You did it the right way - go on your own sans the crowds.