Subject: [Tweeters] RFI: Winter active bats in WA state
Date: Feb 15 18:27:02 2011
From: Greg Falxa - GFalxa at cascadiaresearch.org


In response to Stefan's request - RFI: Winter active bats in WA state:

> Does anybody know what kind of bat that could have been?

Nice report, Stefan. I wish I could narrow it down for you, but here on the wet side of the state we've recorded at least 6 species out moving around during the winter months (using ultrasonic detectors & a webcam), so it's not really possible to determine which species you might have been watching. If it was foraging in the canopy, then the long-eared myotis, Calif. myotis, Long-legged/Hairy-winged myotis , or Townsend's big-eared bats are the likely suspects...

The majority recorded here during the winter have been California myotis and Silver-haired bats, which can are found foraging on winter evenings if the weather is not too crummy and temp. is at or above around 40F. I wouldn't call 40F a warm evening, but warmer evenings *do* produce more 'echolocation hits' on the bat detectors.

There are also published and non-pub. reports of bats seen or 'detected' flying in subfreezing conditions, on both sides of the Cascades (and beyond), some when air temp. was down into the 16 - 20F range. Jon Lucas in the tri-cities area has recorded bats flying on nights that were well below freezing.

Also, I assume you saw this bat in the daytime or at dusk conditions -- maybe it's an owl avoidance strategy! I receive occasional daytime bat flight reports, and I once had a radio-tagged Big brown bat (Eptesicus fuscus) that spent 5 days on an afternoon foraging schedule during a spring beetle hatch. Occasionally daytime flight of bat reports appear on Tweeters, like this one from Mike D. :

--------copied from Mike's post --------
> Mike and MerryLynn m.denny at charter.net
> Mon Feb 2 20:41:33 PST 2009
>
> Hello All,
>
>On 2 Dec.2002 MerryLynn and I watched a Big Brown Bat
> fly out from under a talus slope west of Windust Park along
>the Snake River. The air temp had spiked into the high fifties.
>
>Later Mike
--------end of Mike's post----------

Thanks for the post, I'll add this to my growing list of anecdotal winter (and daytime?) bat reports. Some winter bat into is on our web site <http:www.cascadiaresearch.org/bats/winter>

Greg Falxa, Olympia, WA
gfalxa at cascadiaresearch.org

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