Friday, June 12, 2009

Open-Source Bats

Bat calls, "songs" to keep to the theme of this blog, are hardly inarticulate shrieks. In fact, bat echolocation calls are finely honed sonar pulses and have a complex and time-varying structure. The audio and rather low-resolution spectrograms in my earlier postings should hint at that.

There's a fair amount of interesting scientific research out focusing on bat echolocation, in a much more systematic and detailed way. I was delighted to find not only the article below, but an entire on-line journal whose content is completely free, readily accessible, and freely redistributable.

For example, the graphic at the top of this post, which shows the frequency composition of several individual bat calls, comes from The Voice of Bats: How Greater Mouse-eared Bats Recognize Individuals Based on Their Echolocation Calls.

The authors here show that in addition to all the sonar ranging information encoded in bat calls, there are also individual differences and these differences are recognizable to other bats. They say:

Animals must recognize each other in order to engage in social behaviour. Vocal communication signals could be helpful for recognizing individuals, especially in nocturnal organisms such as bats. Echolocating bats continuously emit special vocalizations, known as echolocation calls, and perceive their surroundings by analyzing the returning echoes. In this work we show that bats can use these vocalizations for the recognition of individuals, despite the fact that their main function is not communication.

Yovel Y, Melcon ML, Franz MO, Denzinger A, Schnitzler H-U, 2009 The Voice of Bats: How Greater Mouse-eared Bats Recognize Individuals Based on Their Echolocation Calls. PLoS Comput Biol 5(6): e1000400. doi:10.1371/journal.pcbi.1000400


Now the abilities of at least some bats to recognize one another's songs is an interesting finding in itself, but what I really like about this article is the philosophy of open research enabled by the journal in which it appears. The articles in the Public Library of Science Journal Computational Biology are freely available under a Creative Commons License. You can download them, read them, comment on them, and upload them to your own site, as long as you accurately attribute them.

I don't know if you've ever had the misfortune to try to download an article from some of the more Intellectual Property-obsessed scientific publishers, but it can be a real hassle. I recall one attempt to buy an article on Organizational Psychology from a well-known publishing house. My wife was in a red-hot hurry for this article in preparation for a job interview the next day.

Not only was the e-commerce part of the web site needlessly complex and cryptic, but when the article for which I paid $35 never arrived as promised by e-mail, we began a saga of phone calls and e-mails that spanned two continents. Turns out that the reason they didn't answer the number provided for technical problems during what seemed normal business hours here in EST was that the number rang in the UK.

Someone from the UK eventually returned the call a few days later, and ultimately my card was credited for the purchase price. It seems that once again, one publishing house had acquired another, and the integration wasn't going smoothly (surprise, surprise). By the time all this was complete, we could easily have gone to the college library and photocopied the article, and for about $33 less, too.

We never got the article. Congratulations old-line publishing house, your intellectual property is safe -- so safe that even those folks who might, out of desperation, pay your inflated prices can't get it.

PLoS is a pleasant change of pace. I think folks like this, along with the legions of scientists who understand that science benefits when information is shared, and not when it is hoarded, will gradually drag the old-line publishers into the post-copyright age, but if my experience is any guide, it may be painful and slow.

In the meantime, let's celebrate the availability of open-source research to complement our open-source software.

Now which bat was that I just heard -- I could almost make out little Vlad's call...

Friday, June 5, 2009

Mortality

Looks as if my explanation the other day for the high level of daytime excitement by the bats was both too pat and too optimistic.

It turns out that the individual whom I could see so clearly on the landing area of the bat house was not so much protective as in need of protection -- this bat was injured and subsequently died.

Looking up the next morning, I saw this:
Not good. I carefully removed the poor thing's body from the landing area (with a stick and gloves) and took a couple of pictures before burial.

Here's one closeup (color-enhanced):

We're looking at the deceased bat's back. The folded wings end at the top with a claw (a vestigial thumb?) used for climbing around in the bat house, and you can clearly see a foot with tiny claws at the bottom of the picture. This unfortunate individual is about four inches long.

I'm sure that there is substantial mortality among bats, like any wild species, but in the three years or so that I've been paying attention to the bats in my bat house, I had never actually seen a sick or injured bat. And since White Nose Syndrome is killing many bats in the Northeast, I was really concerned about what might have caused this bat to die.

Fortunately, the expert folks at the Florida Bat Conservancy were kind enough to look at my pictures and answer my concerned e-mail. Assistant Director Jennifer Smith writes, in part:

As of now you shouldn't be concerned. From the picture it looked like the bat had a broken wing and couldn't fly out each night to forage for insects. The bat's wing bones are very fragile and can break easily. Due to the bat's high metabolism, it doesn't take long for a bat to starve to death. The wound site might have been infected as well. ...

White Nose Syndrome hasn't spread this far south. It started off in New England and has spread farther down through Pennsylvania and West Virginia. So far it's affecting the cave dwelling bats and scientists are still trying to figure what is actually causing it. They are starting to link it to pesticide use on agricultural lands. We hope that it never reaches us!


I was relieved. Jennifer's observation about the broken wing fit with what I had observed the day before the bat perished, when he or she was carrying on in daylight outside the bat house. The bat I saw that day was flexing one wing while vocalizing, and now it seems that may have been because the other wing was injured. Sad, but not as sad as if we had a virulent bat disease like White Nose Syndrome to worry about -- yet.

So far, all the remaining bats (about 25 as of my last visual count) seem fine.