Wednesday, May 21, 2008

Bat Identification

While doing fieldwork along the local creeks yesterday, I spotted this bat flying around in the middle of the afternoon over the creek, then perching on a nearby tree. I'm pretty inexperienced in bat ID, so let me know if you can figure this one out:


  1. I'm no bat expert, but I did look in my Stokes Bat Guide - which is a good little book. The most common NY bats are Big Brown, Little Brown, and Northern Long-eared. They are all pretty similar. How big was it?

  2. I had a ruler in my pack, but didn't measure it. It was clearly agitated by my presence when I approached for better pictures. I have no real experience for relative bat sizes, so I can't really make an accurate guess.

    ~ Nick

  3. I'm just barely getting to know bats, but I don't see why it wouldn't be Little Brown.

  4. Also, not a bat expert, but thanks to some research and a class or two, I'd take a guess and say it was a Little Brown, but it's a tough call.

  5. This winter, bats were emerging from hibernation prematurely, many with what has been called "white-nose syndrome". Many of them died, seemingly from starvation.
    Thought you might be interested in reading more if you hadn't already heard of this issue, which from what I hear is still being investigated.

  6. Nick...tsk tsk, don't you remember anything from Charlie's mammals labs, or perhaps TAing them?

    Anyhow, I'm 99% confident it's a Little Brown. They can be very tricky to tell apart, and size is useless most of the time; but there are two good features to use.

    The first is the spacing of the lines in the skin-fold between the leg and tail...this is the one Charlie taught us, but I can't recall it.

    The other is the size/shape of the snout. Little Browns like your guy have an anteriorly-compressed snout that seems almost "mashed in", and is also nearly entirely covered in fur.

    Big Browns have a more elongated, hairless snout. Here are some photos for comparison:

    Little Brown -

    Big Brown -


  7. Thanks all. I am now confident it is a Myotis, and probably M. lucifugus. There are other Myotis in NY though, but I don't know how to tell them apart.

    Scott - I never liked mammals. I remember everything else Charlie taught me (I think).