Bat Flight from Rose Guano Cave

One evening this past week I had the opportunity to go to Rose Guano Cave in eastern Nevada to watch the bat flight. This cave is an important migratory stop for Brazilian free-tailed bats (also called Mexican free-tailed bats; Tadarida brasiliensis), with over a million using it each year. They usually stay for one to four nights, heading out to feed on insects that are especially prevalent over the nearby agricultural fields.

From the highway, the cave can be seen, near the base of the cliffs (left-center of photo above).

The road towards the cave is rough and definitely requires high clearance and four wheel drive. We parked next to a trailer that is being used by graduate students to study the bats (more on that later), and then hiked the old road towards the cave.

The late afternoon sunlight was superb against the limestone. The first attraction we noticed was a huge limestone arch. Then we could see the gaping mouth of the cave. The old road ended at the base of a tailings pile. This was from an adit built in the 1920s to mine guano out of the cave. The guano is rich in phosphates and nitrates and was used to make gunpowder. Because the adit upset the natural airflow in the cave, it was sealed in the 1990s.

Inside the cave mouth it says "Positively No Trespassing. Rose Guano Mining Claim."

It's steep to get up to the cave, and a rope was installed as a handline to make it a bit easier. We could smell that guano as we got closer to the cave.

On the way we passed a thermal-imaging camera. This was installed earlier this year to record the bat flights so more accurate counts can be done. The bats in the cave have received a lot of attention in recent years due to nearby wind farm proposals.

A sign outside the cave entrance provides more information about the bats (click on the photo to enlarge it).

Below the cave entrance, sitting in a chair with a camera by his side was Peter, one of two field technicians helping two graduate students learn more about the bats. The two graduate students had spent the previous summer counting the bats every night, and they liked it so much that they decided to do further studies and return again. They work closely with the Nevada Department of Wildlife and the Bureau of Land Management to not only count the bats, but also find out where they go. One hundred transmitters were attached to bats over the past couple of years to track where they go and how long they stay in the area.

Even though there is a camera that records the entire bat flight now, they are continuing to count the bats nightly to compare the past method counts to the new counts.

We climbed up to a rock next to the cave entrance. From there we could see that the cave entrance had some special lights in it (that we couldn't see when they were on) to help the camera images.

Jason, an NDOW wildlife biologist, came out to explain to our group more about bat biology and their use of the cave. As he was talking, we saw the first bat come out of the cave--and then turn around and head back in, presumably to tell the rest that it was time to start heading out.

Then more bats started coming out. They looked a little like a stream, flowing by quickly. Then the number of bats increased, and instead of flying straight out, some swirled a bit--the stream was bigger and had some whitewater.

As it got darker, we found that our vantage point was a bit high because the bats blended in with the rock behind them. So we moved down next to Peter and saw the bats silhouetted against the sky.

Jason pulled out a camera and showed us a video of the bats from inside the cave. They come from a deeper chamber in the cave and swirled around twice to gain elevation before they flew out of the cave. It looked really neat.

He also had a thermal-imaging camera with him. Using that, I thought the bats looked like fish swimming in a fast current in the ocean. Jason estimated that about 2,000 bats per minute were flying out of the cave.

By 8:20 p.m., it was too dark to see the bats with the naked eye. Jason said they would continue until about 11:00 p.m. The bats primarily use the cave from July into October.

I couldn't get a photo of the bats flying out, but you might be able to see them in the video below. They are really amazing animals, and with such strange life histories. I can't wait to learn more about them.

Mud and Dancing in the Backyard

We had a wonderful weekend getaway, off to the Midwest for my youngest brother's wedding. Now we're back, enjoying the end of our desert summer. That means lots of outside time.

And playing in mud.

Desert Boy asked me so politely, "Mom, may I play in the mud, please?"

Of course I had to say yes.

Then he went on to other activities, and Desert Girl took her turn in the mud.

Here's a little video of some of the backyard fun:

Tractor Kids

 It's been awhile since we've played on tractors, so it was time to head down to the lower shop and give the kids a chance to "drive."

 Desert Girl looks a little alarmed while Desert Boy gets into some wild driving scenarios--at least in his mind.

 Desert Boy shows Mom what's going on inside. Then he takes off and heads to other equipment.

 Desert Girl is ready for her turn. Even though she has to stand on the seat in order to be able to reach the steering wheel, she's ready to go.

 Look, Ma, I'm doing it!

Afterwards she has a special bounce in her step.

A Walk to the Lakes

On Saturday we joined some friends to do the lakes loop trail. It starts at nearly 10,000 feet elevation and is about 2.7 miles long. Our goal was to make the three- and four-year olds walk the entire way.

The first destination was Stella Lake, and although Desert Boy is usually a good hiker, he didn't eat enough for breakfast and complained almost all the way there. I was wondering if we were going to make it!

Fortunately we did! The photo above shows some of the historic dam that was built to increase Stella Lake's capacity.

It was warm and we wanted some shade and other hikers had claimed spots in the nearby shade, so we decided to go for an "adventure walk" and go to the other end of the lake.

The clouds were so neat!

We finally made it and found a nice spot under these Engelmann spruce. I had visited them in April and May to put a camera up to photograph the lake and help determine when the ice melted off it. Do you see the camera in the photo? Look about halfway up the bigger tree on the left. Yep, it was 15 feet off the ground. I managed to climb up to it, but I didn't have a very good purchase so couldn't stay there long.

Meanwhile the kids were having fun seeing how far they could wade into the lake before they got yelled at. Fortunately they could be redirected by throwing rocks in the lake. Then it was a game of throwing rocks while you were as close to the lake's edge as possible (or in it).

After consuming copious snacks, the munchkins were ready to continue. They were oh-so-cute as they joined hands and headed up the hill.

Desert Boy had chosen to wear one of Desert Girl's socks, which wasn't working out so well for him. Charlie didn't mind an extra stop.

Desert Girl loved hiking with Nomi. She held her hand for a long way.

We found lots of trees that had fallen, and the kids liked looking at the roots. Even though the trees are so tall, they sure have shallow roots!

Desert Girl liked hiking the downhill bits best.

Then it was time for another adventure--crossing a log over a small stream.

This led to another camera high up on the tree.

It was overlooking Teresa Lake. I had never seen it so high and aquamarine-colored in August as that day. It was absolutely gorgeous.

The datalogger we have in the lake and are scheduled to get the end of September might only be reachable by snorkeling. I'm not sure if any one is ready to volunteer for that!

After more snacks, it was time to go again. Charlie liked driving his motorcycle down the trail. Desert Boy interrupted the normal forest noises with his loud train whistle. Brandon was the best hiker, never complaining. All of them hiked the entire way.

When we got back, the kids found instant entertainment in the water fountain. Even though we hadn't let them swim in the lakes (which they wanted to do), they found a way to get soaking wet!

Caption Ideas?

This is what Desert Boy chose to wear one day this week. I didn't know what to say. I'm not sure he did either. I think he has on two different shoes because he couldn't find two of the same kind, but I'm not totally sure. His clothes are on backwards more than frontwards, but somehow he managed to get the shorts on sideways. And he really likes to dress up, hence the turtle tie.

If you have any insights into four-year old thinking, please share!