Volume 16, Issue 1, Spring 1998

Bat Crumbs: What I Learned from a Palid Bat's Leftovers

Encouraged by her teacher's love of bats, a student's curiosity takes her all the way to the state fair . . .

By Muller, Kate

Encouraged by her teacher's love of bats, a student's curiosity takes her all the way to the state fair . . .

By Kate Muller

One day a couple of years ago, my mother showed me a jar that was full of disgusting little things. She had been sweeping the porch and collecting this stuff that looked like insect body parts. She wasn't sure what kind of creature was responsible for these leftovers, but something appeared to be eating over our front door.

I asked my science teacher, Mrs. Martinez, about it, and she said, "Oh, you might have pallid bats (Antrozous pallidus) feeding on your porch." By coincidence, our seventh-grade class was in the middle of a unit about bats, because Mrs. Martinez, a BCI member, is crazy about them. She became interested in bats in 1990 while on a trip with Dr. William Lopez from the University of Mexico. Mrs. Martinez also presents science classes to teachers all over the United States as an instructor with AIMS (Activities Integrating Math and Science). Her favorite classes to teach are just about bats.

Mrs. Martinez told Dr. Lopez about the bat on my porch, and he asked if I would collect the "leftover" body parts and send them to him in Mexico for analysis. I thought: "Why not do the whole project myself for eighth-grade science fair next year?" Mrs. Martinez helped make up my mind when she took our class on a field trip to the Lawrence Hall of Science in Berkeley to see the special BCI bat exhibit, "Masters of the Night."*

That January, 1996, I started collecting data by recording our high and low daily temperatures and watching for any sign of the bat returning. In the second week of March, I realized the bat had come back and was feeding because I found uneaten parts of Jerusalem crickets on the porch. The next night, the temperature dropped, and the bat didn't come back for a few nights. Then it returned every night through November. I picked up insect remains every morning and also recorded high and low temperatures for my area, which is Valley Springs, California, 50 miles southeast of Sacramento, at roughly 668 feet elevation.

It was challenging work to find all the little insect parts left on my deck. I put down a piece of plywood so no bug parts could get lost between the cracks of the deck. Every morning I went out with tweezers and picked up the remains. With a few good library books, I learned how to identify each insect remain, and I began sorting them into separate containers every day.

The trick was to decide how many insect parts to count as one insect. For example, the bat always ate the soft body of Jerusalem crickets and then dropped the legs and the mandibles. Sometimes it would drop the whole head, but usually just the mandibles. I decided to count the mandibles rather than the legs, because an insect could be missing legs and still be alive. So, for my data, two mandibles equaled one cricket.

Based on what the pallid bat dropped during the months it used my porch as its night feeding roost, I know that it ate the following prey: 437 Jerusalem crickets, 120 yellow vaejovis scorpions, 8 praying mantises, 1 ten-lined June beetle, 1 California katydid, 1 field cricket, 3 paper wasp larvae cells, and 4 giant root borers.
By the spring of 1997, I had a year's worth of data, which I started to organize into my science fair project for eighth grade. On May 10th, I placed ninth in the fair. I then went on to the Calaveras County Science Fair the following weekend, where I won first place! The next stop was Los Angeles, for the California State Fair. I got to fly down and stay in the dorms at the University of Southern California. The state science fair was held in the auditorium on campus, and there were 964 projects.

For three hours, I explained my project to thirteen different judges. Some of them expressed genuine interest because, even as scientists, they knew so little about bats; most of the other zoology projects were on worms, flies, and owl pellets. After a long day of describing my research, I was excited about the awards ceremony to come. The announcer finally got to the zoology section, and when she called my name for fourth place, I simply couldn't believe it.

I feel really good about learning about bats, not only because I won at the state fair, but because I educated people around me and changed some people's opinions about bats for the better.

In July, I discovered that my one pallid bat had been joined by at least twelve others. We no longer use our front door for fear of disturbing my ongoing research project!

As of January 1998, I am starting a new project concentrating on the relationship between the temperature and the kind of insect eaten each night. I am also curious to see if El Niño will cause changes in the pattern I found last year. Luckily, my family agrees that use of the front door is a small sacrifice to make for science.

[Author Bio]

Kate Muller is currently a ninth-grade student at Calaveras High School in San Andreas, California. BCI has awarded Muller an honorary one-year membership.

The author poses with her exhibit poster and first-place trophy at the Calaveras County Science Fair in April 1997. Included in her exhibit are photographs and sample body parts of six of her pallid bat's most common prey, as well as small plastic bags showing typical assortments of parts the bat discarded each night.

The author experimented with different cameras, speed settings, and film trying to take a picture of the bat on her porch at night without disturbing it. She finally got this picture one lucky afternoon when the bat remained roosting on the porch throughout the entire day.

The author's project includes a series of monthly graphs showing how many of which insects the bat left on her porch each night, as in this example. She also charted high and low temperatures for each day on transparent overlays, shown here as a composite drawing.

All articles in this issue:

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