Into a Bat Swarm

Last fall, I had the chance to visit a cave in Kentucky where the bats were swarming. Most Eastern cave bats swarm in the fall as a part of their mating behavior. Here’s a one-minute nature video from my visit.

 

Bat Talk Translated!

Bat talk has been translated, indeed! (Click to see original article.) This is way cool! Researchers have used computers to translate animal talk, specifically some fruit bats. They found that these bats did not make random noises, but had very specific communication needs and even spoke to specific bats as individuals. The scientists used speech algorithms to compare vocalizations of the bats while at the same time recording them on video. This allowed them to connect specific vocalizations to specific behaviors. They seem to argue a lot!

 

Bats Fly Faster Than We Thought!

Bat flight

Mexican free-tails are among the fastest of flying animals.

Recent research has found that Mexican free-tailed bats can reach 99 mph in level flight. That is better than any bird or other flying mammal! And it’s fast!

The bats reach these speeds for short periods of time, and scientists are not sure why they go so fast then. Flying is very energy intensive, and fast flying just intensifies it even more.

Mexican free-tails are built for speed, with long narrow wings and small, streamlined bodies.

You can learn more here. The photo shows Mexican free-tailed bats leaving a bridge north of Austin, Texas, at dusk.

Bat houses

Bat House up north 700wBat houses are great, but bats are particular and you never know if they will occupy one or not. Why is not fully understood. You can have two identical bat houses in a yard and one gets occupied, the other does not.

I did a bit of research about bat houses before purchasing one for our yard at our mountain home near Lake Isabella, California.I got mine from Bat Management — http://www.batmanagement.com/Ordering/ordermain2.html. They are a small company in Pennsylvania that specializes in bat gear. I would recommend getting a bat house from a supplier that actually works with bat houses. Amazon doesn’t care about selling bat houses, only about selling something. Many of the bat houses on the site are too small. Bats don’t like small bat houses, partly because the internal temp will vary too much. 

Because bats fly, they move around a lot looking for food. Some bats will travel many miles for good feeding grounds, though the common myotis bats probably not travel more than 0.5-1.0 miles. They are the ones most likely to use a bat house. That can be a big deal to having bats around to help control insects. And it helps bat populations suffering from white nose syndrome.  

If you have troublesome bats roosting in your attic, have a bat “exterminator” who knows what he or she is doing come out to your place. If they know what they are doing, they will not recommend killing the bats (it is illegal anyway in most areas and that would stink up your house). They should evaluate your house to see where the bats come and go from, then put a special “exit-only” tube there. That way when the bats leave at night, they cannot get back in, and the exterminator can then close up all the holes where they get in (it doesn’t take much of a hole in size for bats to come in). 

http://www.batcon.org/resources/for-specific-issues/bats-in-buildings

If you exclude bats and have bat houses up, there is a better chance of them starting to use the houses.

Amazing Mexican Free-Tails in Austin

Austin Bats 8We had to privilege to experience some amazing Mexican free-tailed bat emergences in Austin over the Memorial Day weekend. The bat colony under the Congress Ave. bridge just south of downtown Austin is well known. Hundreds of people show up to watch every night, and on busy nights, that can be thousands. You will see every age, sex, culture and race there to see the bats. They have become a popular destination for folks coming to Austin. Over two million bats live in that bridge, the largest urban bat colony in the world.

We were there on a busy Saturday night – the park and lake below the bridge were filled with people. At this time of year when female bats typically have young, the Mexican free-tails often emerge earlier than sunset so they can get out and start feeding. There had been a lot of heavy rain in the area in the days before, so the bats would not have gone out much to feed, if at all.

But they did not start coming out until nearly 9 pm, about 30 minutes after sunset. It was definitely night and dark.

Austin Bats 2The bats became very hard to see. I had to use a flash to get anything, and only when the image showed on my LCD did I really see the bats. The local folks said that a hawk had been hanging around the bridge of late and that probably caused the bats to delay emerging until it was dark.

A friend who lives in the area, Ted Keller, had suggested we check out the I-35 bridge over McNeil Rd. in Round Rock (just north of Austin). He said that bridge also had millions of bats using it as a bat “house.” We went there on Sunday night. The evening was sunny with hardly a cloud. The bats started coming out a little before official sunset and this was an amazing nature experience. My wife loves nature, but does not have the love of bats I do, but she was in awe and loved it. The bats swirled under the bridge, then came out in large groups out of the southeast end of the bridge.

Austin Bats 3Austin Bats 4The groups went into the sky and you could watch them go. The mass of bats and their group flight in the air reminded me of the starling flights going to roost in England (I have only seen videos of them). There were not many people there to watch, but they all just stood and watched with great attention as these bats came out in waves over the next half hour (they actually kept going longer, but when it was dark and getting hard to see them, the people left).

Next day, Monday, sunset came. No bats. The bats did not start coming out until nearly 9 pm, like the Congress Ave. bats. I had seen a hawk fly through the flying bats on Sunday night, and it seemed like it caught a bat, though it was hard to tell at the distance.

Austin Bats 5I get it. These little bats are very vulnerable when it is light, so they delay emergence to make it harder for hawks to get them, even though that means going out for food later (bats have a very high metabolism, especially with young to feed, so that does matter).

Austin Bats 6Still, it was fun and I learned a lot.

Austin Bats 7

Behind the Curtain

Curtain + BatNature can be an amazing place. Yet, we can easily miss parts of nature that could be amazing, remarkable and enjoyable simply because our senses are not capable of engaging with everything nature has to offer.

Earlier this month, I was up in the mountains near Lake Isabella in Kern County, California. I knew there should be bats at this location, so as night arrived, I was outside with my iPad and Echo Meter Touch. The Echo Meter Touch, along with the app the iPad app for it, allows you to “hear” bats. It has a high-frequency microphone module that plugs into the iPad (or iPhone). When the app detects bat sounds from the module, it alters the frequency so we can hear them, plus it creates a sonogram or graph of the sound. Then it suggests the top bat species that the bat could be. This is really cool and gives an idea of bat activity and possible bat species.

This has been an interesting experience. I love discovering this part of nature, a key part of nature that is often missed because bats don’t follow our schedules. But the idea that our senses are not capable of engaging with everything nature has to offer really hit home this last time “listening” for bats near Lake Isabella. I started checking for bats about 20 minutes after sunset and kept the detector on for 30 minutes. The Echo Meter Touch showed me I had 29 passes of 6 species of bats during that time. That was pretty good activity! (The list you see here has been cropped and modified in form so as to make it more readable for the blog.)

Bat recording list 5-13-16 modBut … as much as I tried, I only saw one bat flying by. One out of 29 passes! Now admittedly, I am not a young person like my adult kids with great night vision, but even then, it is unlikely that they would have seen more than a few bats. It was pretty dark out.

It was like a curtain of darkness blocked my view of the bats that were there. How often have any of us been in places where these amazing mammals are flying and yet had no idea they were there? This is actually a problem for the conservation and protection of these bats. If people don’t know they exist, no one knows if their populations are affected by environmental pressures from pesticides to global climate change.

Acoustic monitoring, the official name for finding bats by their sounds, is a way of opening that curtain. Scientists can use this to detect and monitor bats in many areas, gathering important information about them. Anyone can also open this curtain if they have an iPad and get an Echo Meter Touch. I am finding it to be a lot of fun!

On the screen capture of bat recordings from the night described, bats are labeled with the first two letters of their genus and first two of their species, the scientific name of genus and species. So for example, LANO is a silver-haired bat or Lasionycteris noctivagans.

Bat Flight

Bat Flight rev 2 Bat Flight rev1
True flight has only been mastered by a few animals outside of insects. Only two higher level animals (vertebrates or animals with interior bones and a spine) have developed the ability to fly when and where they want, birds and bats.

Flying requires a great deal of energy, so both birds and bats eat a lot of food for their size. A bat can eat half its weight in insects every night! That’s like me eating 100 pounds of hamburgers every day. Ugh! But for a bat, that’s just everyday survival.

Birds and bats have evolved differently in the way that they handle flight. For one thing, bats don’t soar like birds do, and they never “surf the thermals” because thermal air currents are day phenomenon. Bat flight had no reason to evolve for that. Bat wingbeats are similar to a swimmer using the butterfly stroke.

A bat wing’s surface is a double membrane stretching between the fingers of its hand. A bird’s wing surface is made up of feathers attached to the arm and hand. A bat’s hand is fully developed and easily seen – the fingers are elongated to create a very flexible and quickly adjusted airfoil for flying. The mammal order of bats is chiroptera, which means hand wing.

Photo Apr 28, 2 27 32 PM

The bird’s “hand” has fused into a few bones at the end of the arm; the feathers themselves are used to adjust the airfoil for flying.

Photo Apr 28, 2 24 40 PMThe muscles are also different, both in how they are formed structurally and how they work. A bird has fewer flight muscles than a bat and is more efficient in flight. The main wing muscles are attached to the keel of the bird’s sternum and are why bird’s chest is so large. Bats have their main wing muscles both in their chest and in their back.

Bats as Introverts?

Bats introvert 1Why should any of us pick a particular part of nature to connect to? We all tend to do this in one way or another. A good friend of mine, for example, loves birds. He spends a lot of time every week photographing them, trying to capture as many different birds and behaviors as he can.

I find bats fascinating in so many ways, but I don’t remember anything about them from when I was a kid. Given the tendency for our culture to find them scary and unwanted, I wonder why. Yes, they are a hugely important part of nature. Yes, they represent a significant time of nature, night, that we often miss as day creatures. Yes, they represent about 1/4 of all mammals and are highly important to many ecosystems.

But why should I want to spend so much time learning about them, and even more, trying to photograph them? They are a difficult part of nature to photograph because they come out at night and have such high mobility as fliers.

I think that one reason might be because they are underdogs. When we learn about underdogs, we often want to support them. That’s true for me, and there is more.

Once you get to know bats, you find that they are gentle, beautiful creatures highly adapted to their life of night predators (and night flower feeders in some areas of the U.S.). They are not showy or dramatic, they don’t call attention to themselves, they don’t have impressive calls or theatrical mating displays, and they are perfectly happy living quietly in the night when most mammals, birds and other wildlife are asleep.

In that sense, they are introverts of wildlife, and I can relate to that. I am an introvert and say that with confidence and pride. Introverts are not “shy” or less valuable to our world than extroverts, even though our society often judges us as such. Introverts simply deal with the world differently than extroverts. We need time away from the others, we get tired from too much noise and activity, and we enjoy a life separate from a social, on-the-go experience.

I know that bats have a variety of personalities like any other animal, but in some ways, bats can be seen as similar to an introvert. Night is quieter, more peaceful usually, with a lot less going on, all something any introvert can relate to. Introverts can focus deeply on things away from others, and night is certainly a time that bats can focus on their “work” catching bugs and not have to worry about competition from other wildlife or predators after them as they fly. It makes an interesting comparison, anyway.