>From John Tebbutt
Frederick, MD
tebbutt at nist.gov

This morning I was just about to pick up and take off from a
disappointing and mosquito-ridden Project Tanager census at
Mouth of Monocacy in Frederick County, MD, when a BARRED OWL
saw fit to let out a few calls in the near distance. Of course
this drew an immediate and angry chorus of screeches, tweets,
caws, rasps, mews and all manner of other calls.

Never one to put science before a good owl :-) I, too, rushed off in
the direction of the original owl call and the growing cacaphony.
Though I peered through dense canopy for a few minutes, all I could see
was the little army of screeching passerines, but eventually the owl
obliged by flying into a more open area, alighting on a bough, and
glaring at me, angrily. I got a nice, and really quite close up, view
of the creature (my favorite owl :-) ).

This is the first time I've seen a full-blown owl mobbing, and I must
say it was quite an impressive event. I was left wondering what led the
owl to call in the first place, and concluded that maybe it happened
involuntarily in its sleep (my wife said something like "They haven't
put the barrels out yet" loud and clear the other night). What a great
start to the day!

Best, JT

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From: "Peter IronsDr. Peter Irons" <GESLAG9 at OP1.UP.AC.ZA>

John Tebbutt surmised about the reasons a barred owl would call in
broad daylight. Now I know nothing about your barred owl, but our
pearl-spotted owl (Glaucidium perlatum) does this quite frequently,
and when he's (or she's) wide awake.

I heard a talk recently by Geoff Lockwood, our local owl fundi, and
he gave an interesting reason for this apparently mindless behaviour.
He reckons they do this to actively attract mobbing, and then when
one of the more diminutive mobbers gets careless they pounce on them;
a sort of food self-delivery service. It bears mentioning here that
the pearl-spotted is tiny as owls go, barely bigger than most small
passerines, so injury to the owl by agressive mobbing must be a risk.
To this end, they have eye-spots on the back of their heads to make a
would-be attacker think thrice.

I don't know how true it is, but it's a good theory.

Peter Irons
GESLAG9 at op1.up.ac.zaDr. Peter Irons
Dept. of Theriogenology
Faculty of Veterinary Science
University of Pretoria
Private Bag X04
Onderstepoort 0110
South Africa