how deep in a cave will a bat fly?

[sinukas]

How deep in caves do bats fly to perch? It seems like they generally gather relatively close to the entrance, but some times I will see large groupings of bats really deep in the cave too. Does anyone know?

[Phil Winkler]

Bats generally go to areas where the temperature suits them best. Entering Fern Cave thru the Morgue Entrance you rappel a couple of hundred feet down and then traverse quite some distance to where the colonies are. In other caves you can find bats hundreds or thousands of feet from the entrance. So, I'm not sure there is a hard and fast rules the bats follow.

[GypsumWolf]

I see them just about anywhere in a cave but I rarely see them in a main stream passage.

[tncaver]

I recently visited a cave with bats (not the endangered variety) scattered throughout the entire cave. Yet in some caves
bats only roost in one or two locations. It does make one wonder why they choose to roost where they do. Regardless,
I did and always do my best to not disturb bats when ever I must pass near them to go deeper in a cave.

P.S. No sign of White Nose Syndrome in that Tennessee Cave.

[Ralph E. Powers]

Here in TAG I've seen them in as far as the passage just before you get to the Rumble Room at Rumbling Falls Cave. That's a good mile in. Others I've seen fairly deep. It's a puzzlement to me why they would go in THAT far but they do. Some of them must manage amazing aerobatic feats to get through the low crawls and ups and downs to get in that far.

[Vertigo]

I've seen bats at the very end of a cave before...maybe there's another entrance?

[wyandottecaver]

As has been mentioned, several things factor in.

Most important is micro-climate. i.e. how warm/humid the "sweet spot" they are seeking is. This often changes seasonally even during hibernation. entire clusters of indiana bats comprising thousands of individuals have relocated during just a few days within a hibernaculum. Outside or inside conditions (barometric pressure, floods, extreme temperature changes) can change these areas. temp/humidity can vary widely over the course of a few days or weeks even deep in the cave.

In dry and or windy caves they will also travel to wet areas periodically for moisture. Some bats like pipistrelles seem to prefer roosing in wet areas, possibly to defray dehydration. some bats (like pips) also seem to prefer solitude, generally roosting as singles or small groups and others like indiana's tend to aggregate.

Disturbance by people and predators can also influence roost areas.

As some note, it is also possible that these deep areas are near a bat-sized entrance crack.

One notable cave in S Indiana was dug open after seeing bats crawl out of an otherwise unimpressive entrance breakdown pile.

I think pipestrelles are just hardcore cavers! I have seen them roosting in the most remote, miserable, god forsaken places like 6' high wet muddy waterfall domes after hundreds of feet of miserable belly crawl in a cave where the bulk of the pips were in a main passage 1 minutes walk from the gate...

[Squirrel Girl]

I'm pretty sure I've seen bats in at least a half mile in several caves.

[George Dasher]

Here's some of my personal observations while caving...

Pips are the hardcore cavers. They go everywhere in a cave, except really, really deep. Once you get past a certain distance in a cave, the only bats you will see are pips. They're pretty obvious since they hang alone and are hard to disturb. They are also a very calm bat, and they are a weak flier that flitters up and down when they fly. If you're a half mile into a complex cave and see one bat hanging on the wall (which doesn't wake up as you pass by, eat lunch, change carbide, sing the Star Spangle Banner, etc.), that's an eastern pip.

My experience with the rest of the bats is that they stay closer to the entrance, but they they can still be 100s or 1000s of feet into the cave. I think a lot of depends on the cave passage.

Little Browns and Indianas hang in clusters. One of them hangs like shingles, and I think (but am not sure) it is the Little Browns. Big Browns also hang in clusters, but they're usually in smaller clusters. They're most obvious because of their size. There's not a lot of Big Browns around.

Big Browns are strong fliers. There about the size of a softball and will wake you up when they go by. Little Browns fly like they have a rocket up their ass. There is NOTHING weak about their flying and they can fly very straight. They'll actually have you trying to dig a hole in the floor of a crawlway to get away from them. We had to abort surveying a passage one time in Pendleton County because the Little Browns were buzzing us, and we were too busy trying to pull our heads back into our coveralls to do any surveying whatsoever.

Virginia big ears are just plain spastic. They roost in the biggest colonies, and they have a severe wiggle factor before they fly. Once they fly, they have to fly up and down, and up and down, and up and down the passage before they leave. They are a biggish bat and they flitter when they fly. Big ears are obvious because of their big ears, but not as obvious as you think, because they keep their ears curled up when they are roosting. Mostly they're obvious by their many large groups and their twitter factor. But the MOST obvious thing about a big-ear cave is that they are a guano bat. Guano is very slippery. Therefore, if you suddenly find yourself falling down, or waving one foot above your head while you slide out of control down a not-so-steep slope, you're probably in a big-ear cave. Big ears also like to roost in cracks in the cave roof, and that leaves an obvious red guano streak below the crack.

I think pips are my favorite bat. They go far into the cave, and they are so calm. And they'll roost in the most miserable crawlway you can find, and they're the ones that are usually covered with water drops. They're particularly nice to be with after you just spend ten minutes enduring a big-ear colony flying back and forth and back and forth before leaving the area.

[Ralph E. Powers]

Thanks George.
Bats are so cool!

[wyandottecaver]

To add to george's "bat guide" though from a researcher viewpoint.

Gray bats are the jumpiest. They start vocalizing as soon as they detect your presence, and just about the time you say to yourself, "hey those are gray bats" the entire colony around you, however hundreds or thousands strong it may be will suddenly all take off at once and fly about for a while and then skeddadle en masse. Bachelor colonies can be in dry caves but maternity colonies (with young) are over water. If you are swimming/wading in a cave in summer and are suddenly surrounded by a cloud of upset bats...leave immediately. Grays are also guano bats, so if you are seeing big hills of black sand in the midwest...only it's not quite sand...your probably in a gray bat cave.

Eastern Long-eared bats seem to be the most ill-tempered at being handled and vocalize profusely while trying to exact vengence. They also like cracks and fissures. They sometimes magically appear in caves around dusk. They are called long ears because their ears and the little flap inside them the tragis is long...but only in comparison. most people wouldn't notice a difference without comparing them side to side to a "normal" eared bat.

Pips, while calm at rest, are the opposite when being measured, weighed, and otherwise provoked. they are nearly as vocal as long-ears and just as bitey, though they cant consistently get through skin let alone gloves.

Little Browns have a tendency to often be wet and nappy looking when plucked from the air by a harp trap, while Indiana bats are nearly always dry and cozy looking. They seem to be more variable by individual as to temperment. some are quite calm and others irritable. They also mostly cant get through your skin...mostly.

Big browns are big and they know it. If they bite you you'll feel it, though gloves help. They are rarely calm. They are rarely found in caves in large numbers though you might find thousands in buildings. Their poop is bigger too. If your neighbor says they are finding rice sized (uncooked) bat poop on the high-school basketball court...they have big browns probably.

Eastern Red Bats are really really awesome and very beautiful. They are virtually never found in caves. They roost in trees and hibernate under leaf litter on the ground. They have teeth like a barracuda and you will cry like a girl if they get you in the soft spot between your fingers. They tend to be mostly calm once you get a hold of them.

[boogercaver71]

Back in 1999, while trying to dig a back entrance(in natural sinkhole) into Carroll Cave (MO), a pip crawled out of the rocks we were moving (70' down). At this time, the only entrance was 7 miles away. Man that little guy had a heck of a flight to go out and feed. By the way, the little guy was taken to the natural entrance and let go.