Sorry,
I forgot to add, I took a snap of the cave as a few bats (five I think) exited:
http://www.flickr.com/photos/aovers/3373339459/sizes/l/
Anthony
-----Original Message-----
From: Overs, Anthony (REPS)
[
Sent: Monday, 23 March 2009 1:58
PM
To: COG List
Subject: [canberrabirds] Wee
Jasper, bats and raptors
Last
Thursday evening I spent a couple of hours at Wee Jasper, assisting an old
friend in the monitoring of a large bat colony right near town.
We
stopped at the tavern for a steak sandwich for dinner, and while sitting
outside I observed plenty of Yellow-rumped Thornbills, Galahs and
Sulphur-crested Cockatoos in the tavern garden and surrounds. A Collared
Sparrowhawk cruised over quite low, but no other birds seemed to care.
Shortly
after, an Australian Hobby flew over, a bit higher, and
heading
south with purpose.
The
cave we were watching is one of only three known maternity colonies in
NSW for the threatened Common Bent-wing Bat (Miniopterus schreibersii). In
the past the cave has been home to up to 30,000 individuals. On Thursday night
we estimated about 15,000, although my friend Doug
has
yet to count them on the thermal camera recording (apparently some software
does it – he doesn’t sit there counting them one by
one!). It’s some of the easiest field work I’ve ever done; 50 metre
walk, set up the cameras, sit in a chair for an hour!
The
bats began to leave the cave entrance (maybe a metre wide), just as the
sun set behind the hills to the west. The light was still very good and the
bats were easily observed. After about ten minutes from the first bat leaving,
the rest followed in high numbers. It took about an hour for the whole lot to
leave. An incredible sight, and also an amazing sound as the many sets of wings
fight to get out of the small cave entrance. Some of the
bats, presumably young ones just learning to fly properly, crash-landed in the
grass occasionally, pausing for a moment then taking off again.
Now,
many moons ago I heard of an instance of an
Australian
Hobby successfully hunting small bats at dusk. Has anyone observed this? As I
sat next to the cave and watched the bats heading out into the woodlands I thought
it
would be such easy pickings for a fast manoeuvrable raptor like a hobby or
sparrowhawk (amazingly the two species I’d seen an hour earlier at the
tavern) to catch a bat or two for dinner. Maybe even a Boobook or Barking Owl
might get in on the action. Any comments?
Cheers
Anthony
