Carroll Cave Trip Report – 25 October 2025

Entrance time = 9:45am, exit time = 7:00pm

Participants: Bill Gee
Mike Kovacs
Candace Kovacs
Jessica Wilson
Jerel Waters
Sarah Peterson

This is the annual bat census trip that we have been running for about 20 years. We accumulated several additional tasks this year which made for a fairly busy trip. The “bat” aspect of the census has, in the last 6 years or so, turned into more of a “sculpin and salamander” census.

I arrived at the site about 3:00pm on Friday. The grass down the middle of the access trail was over a foot high, and there were some woody plants growing in there. The grass inside our fence was about the same height. I noticed that the red cedar trees we planted a few years ago are growing like gangbusters. A couple of the oak trees are gone, but several others seem to be doing well. I did not look for the cyprus trees around the frog pond.

I set up my camper, then went into the container to get the mower. It took me ten minutes to figure out the right sequence to get the mower to turn on. The battery level showed 100%. I mowed about 1/3 of our area inside the fence, mainly from the gate to the shelter, around my camper and in the main camping area to the northeast corner. I also mowed a path to the skycrapper. This much took about 30 minutes and reduced the mower battery to 52%. I put the mower back in the container and hooked up the charger.

It takes some practice to figure out how to drive the mower. If you are not careful, it can get into a state where it swings wildly back and forth. The two control arms are not exactly equal. The left arm has to be pushed a bit farther than the right to go in a straight line. The startup sequence is rather finicky. We should make a big poster of the startup sequence and hang it in the container.

Overnight the low temperature was 50F. I heard three drops of rain on my camper. There was some fog and a heavy dew. While we were gearing up a light 4 minute sprinkle of rain came through.

Saturday morning after breakfast and exercise walking, I got out the mower again. The charge was up to 100%. I mowed the access trail from our gate almost to the road gate. It took several passes to knock down the weeds and woody growth, and I had to go fairly slow. The mower blades are really dull which does not help. About 20 minutes and the mower was down to 60% on the battery. I put it back in the container and hooked up the charger.

Rick Hines gave me some repair parts for the string trimmer. It was two springs and a cap for the trimmer head. I installed one of the springs (which did not require any tools), then ran the string trimmer around the shelter and the silo. The new spring worked well. The trimmer has plenty of power, though it did bog down in some very tall reeds around the southwest side of the shelter. The extra cap and second spring are in a plastic bag on the shelf in the container.

Sometime during the night Jessica Wilson came in. She camped in the back of her SUV. Everyone else arrived between about 8:30 and 8:50. Mike and Candace Kovacs brought word that two people had dropped out. One was due to car trouble and the other to impending parenthood.

We all geared up and started down the shaft. First person in at 9:45 and all in by 10:15. The first task was very quick. I exchanged the cave intrusion detector for another. The replacement is built on a custom circuit board while the old was handwired on a prototype board. Analysis of the data collected shows trips from June 2024 to today.

We left the ladder about 10:30. Through the water barrier to the first riffle. We always count and measure isopods at this riffle. This year the count was very low. We only saw four isopods. That might be due in part to the water level being very low. There was almost no flow to the stream, and the water level was several inches lower than usual.

From there we continued to the first set of guano piles. Guano pile number 3 was a bit of a surprise. It has had almost no usage since we started monitoring. Last year it had some and this year it was heavily used. There were a lot of salamanders in the area. I photographed each guano gauge, made some voice notes about the state of the gauge and other things we found, and then the gauges were cleaned off to reset them for the next year.

When we got to guano piles 11 and 12, Candace, Jessica and Sarah went on ahead. One of our additional tasks this year was to collect some fungus and guano samples for Halle Santiago who is a masters student at University of Illinois in Champaign-Urbana. The collection process takes half an hour or so. Several areas on the wall and around a pile of guano are swabbed. Some individual feces are collected. Everything has to be bagged, tagged and notes made of where it came from. Candace has done this in another cave, so she led the group doing it in Carroll. The samples are collected in the dark zone of the cave and also at the entrance. For Carroll Cave we regarded the Mountain Room as the entrance.

The next task on our list was to inventory the rescue caches at the Lunch Room and the Mountain Room. Mike brought along some new cigarette lighters packaged in vacuum-seal bags. Mike, Jerel and I finished the guano gauge documentation, then went on ahead to the Lunch Room. We did a complete inventory of the Lunch Room rescue cache. There was some water inside the dry bag. The contents seemed unharmed. We think the water got in by wicking along the paracord.

The rescue cache is tied to paracord which is in turn tied to the cave. That keeps it from floating away. The balance of the paracord had been stored inside the dry bag, which provided a path for water to get in. When we closed up the bag, we left it laying on its side and we did not put the remaining paracord inside it. There is a 5 gallon collapsable plastic water container next to the rescue cache. It is about half full. We did not open it. I would not trust the water in it.

There was a pile of trash in the Lunch Room. Several glass soda pop bottles (glass!!), some old rusted cans of sterno, a rusted cook pot and a coil of wire were the main items. We set it all aside to pick up on the return trip.

Everyone had a good lunch. We left the Lunch Room at 12:50 to start the bat census. As usual, this section of the cave is very muddy and slippery. We made fairly good time, in part because there were almost no bats. Several of the team kept an eye on the stream where we saw many sculpins and even more salamanders. Many of the salamanders, maybe as much as half of them, were larval and juvenile size under 5cm long. I turned over a few random rocks looking for isopods but found none.

We arrived at the Mountain Room about 3:30pm. That is around half an hour earlier than I was expecting. The water there had a lot of frogs and one big crayfish. There were some sculpins as well. Jerel took on the task of counting critters in the stream from the entrance tunnel to the main cave. I went around documenting and photographing the guano guages. As usual there was no activity on any of them. Candace, Sarah and Jessica did another fungus collection session, and Mike checked out the rescue cache.

This rescue cache had several inches of water in it. As with the Lunch Room cache, we are pretty sure it came in by wicking along the paracord. Mike emptied out the bag, inventoried the contents and put it back together with new cigarette lighters. We left all of the paracord outside the bag. We took a very quick look at the bolt cutter. The handles still move, so it is not rusted completely through. We did not take off the plastic wrap.

Before we left, Sarah treated us to a few minutes of really gorgeous singing. The girl has pipes! A few years ago she gave us a few bars of “Ava Maria”. This time there was some classical and also a bit of Freddie Mercury. Very nice! Candace was able to record it on her smartphone.

We left the Mountain Room at 4:40 for the return trip. It takes about 25 minutes to get to the Turnpike entrance and about 30 minutes to get through the Turnpike. That shortcut is a very different cave than the main passage.

Back at the Lunch Room we picked up the trash to carry out. The last part of this trip always seems to go slow, but in fact we made very good time. We were back at the ladder by 6:30. Everyone geared up and started the climb.

Our last task of the day was to get some photo documentation regarding the state of the ladder rungs. The steel cable was slapping against the ladder for 15 years and has worn holes in a few of them. As I was climbing I kept a watch. I saw four rungs with holes in them. The biggest hole was about 3/8 inch long (about 1cm). Those four rungs were in a sequence along with a fifth rung that had some wear but no hole. They are located on the second 20 foot ladder section from the top. Jerel was able to get some good GoPro video of the damaged rungs.

A few other rungs showed some wear, but none were worn through the ridges. Many rungs were coated in calcite which showed evidence of being knocked off.

The last person was out of the cave at 7:00pm. Mike and I de-rigged the rope. I locked up the cave. The weather outside was raining lightly and the temperature was about 60F. Everyone else left to go home. I had dinner and a shower, then got a good nights sleep. I left the campground at 5:00am on Sunday in a very light drizzle. The low temperature Sunday was 52F.

I put out a rain gauge from Friday afternoon to Sunday morning. It collected about 1/10 inch of rain in that time. The radar rain estimates from Climate.com confirm this.

============== Data Section ==============

Bat and critter counts:

Salamanders are all grotto. Bats are tricolor except as noted.

Lunch Room to 6000 foot: 1:07pm – 4 salamanders
6000 to 5000: 1:39pm – 1 sculpin, 17 salamanders, 1 cave fish, 2 bats
5000 to 4500: 2:06pm – 5 sculpins, 19 salamanders
4500 to 4000: 2:18pm – 4 sculpins, 11 salamanders, 1 bat
4000 to 3500: 2:26pm – 1 sculpin, 1 salamander, 1 grey bat
3500 to 3000: 1:26pm – 1 sculpin
3000 to 2500: 2:36pm – 4 salamander, 1 bat
2500 to 2000: 2:43pm – 1 sculpin
2000 to 1500: 2:51pm – 3 sculpins, 4 salamanders
1500 to 1000: 2:27pm – 2 sculpins, 1 salamander
1000 to 500: 3:13pm – All counts zero. Bat cluster is not present.
500 to Mountain Room: – 3:21pm – 1 crayfish, 11 sculpins, 1 unknown fish, 1 frog
Mountain Room: – 15 frogs, 5 sculpins, 2 large unknown fish, 1 small unknown fish

Isopod count: (Note – these lengths include feelers and antennae)
10mm = 1
11mm = 1
21mm = 1
22mm = 1

We saw two cave fish at the isopod count riffle.

Guano gauges:
Guano gauge 1 = 30% coverage 2mm.
Guano gauge 2 = 50% coverage 2mm.
Guano gauge 3 = 90% coverage 8mm.

6 grotto salamanders 5 to 7 cm at gauge 1
2 grotto salamanders 7 cm at gauge 3
In the stream – 2 cave fish 3 to 4cm
4 grotto salamanders in the stream

Guano gauge 4a = Completely clean.
Guano gauge 4b = 1 turd.
Guano gauge 5 = Completely clean.
Guano gauge 6 = 100% coverage 6mm.
Guano gauge 7 = Completely clean.
Guano gauge 8 = Completely clean.

4 small fish 3 to 4 cm, one adult grotto salamander 6 cm.

Guano gauge 11 = Completely clean.
Guano gauge 12a = 15% coverage thin layer.
Guano gauge 12b = 10% coverage thin layer.
Gauno gauge 13 = 85% coverage 4mm.
Guano gauge 14a = 60% coverage 3mm.
Guano gauge 14b = 4 turds.
Guano gauge 15a = 100% coverage 10mm.
Guano gauge 15b = 80% coverage 3mm.
Guano gauge 16 = Completely clean
Guano gauge 30 = Completely clean
Guano gauge 31 = Completely clean
Guano gauge 32 = Completely clean
Guano gauge 33 = Completely clean

Rescue cache inventories ======================
Lunch Room:
A bag of safety pins
Two Ace Bandage wraps
Two cigarette lighters in vacuum seal bags
Gallon ziplock with several trash bags
7 Lantern candles
A bag of assorted ziplock bags
Matches in a pill bottle in a vacuum sealed bag
Exam gloves in a pill bottle in a vacuum sealed bag
A triangular bandage and two “space” blankets in a vacuum seal bag
A Rite-In-The-Rain tablet and some pencils in a vacuum-sealed bag
50 feet of reflective paracord
A roll-up semi-stiff splint
Four pieces of closed-cell foam
A flexible cutting board

Mountain Room:
A bag of safety pins
Two Ace Bandage wraps
Two cigarette lighters in vacuum seal bags
Trash bags
Tea candles
A bag of assorted ziplock bags
Matches in a pill bottle in a vacuum sealed bag
Exam gloves in a pill bottle in a vacuum sealed bag
A triangular bandage and two “space” blankets in a vacuum sealed bag
A Rite-In-The-Rain tablet and some pencils in a vacuum-sealed bag
50 feet of reflective 550 paracord
Four pieces of closed-cell foam