Date: 9/8/17 7:33 am
From: Dan Nelson <birdsurf64...> [northbaybirds] <northbaybirds-noreply...>
Subject: [NBB] Fw: Bodega Bay - Raving with Ravens

On Friday, September 8, 2017 7:29 AM, Dan Nelson <birdsurf64...> wrote:

Hi Birders,On Wednesday Sept. 6 there were unprecedented numbers of Common Ravens staging on the coast  near Bodega Bay. At one point, I counted 45 circling in the air at one time, over Bodega Head near Owl Canyon and Campbell Cove. At hour later, another large group was just W. of Valley Ford.
While not a rare species, I thought this might be worthy enough to report NBBer's.  Or maybe not.
At any rate, I wanted to discuss the well-known "knocker" call, which is part of the regularly-heard repertoire given by CORAs - but slightly less frequent.  This is a louder, very percussive version of a normal raven call,  and transmits much further distances through open space,. This call is a very important component of Raven communication, and is often heard at places such as Bay Hill Rd., Jenner Headlands, or Marin Headlands. It is usually uttered aerially, in flight, and virtually always DOUBLED.
CAUTION   : A few of the CORAs I reported were youngsters, and have been heard giving their doubled, youngster version of the "knocker" call.  These calls can be heard daily at Campbell Cove, Owl Canyon and vicinity if one puts in time to listen. DO NOT CONFUSE this call with the pre-song clucking of Yellow-billed Cuckoo. The large influx of CORAs may be associated with the explosion of Voles / Microtis #s on the coast, also attracting Barn Owls and others.... which keep the ravens squawking .
Fun times, good birding- Dan Nelson, Sonoma County

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