From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Mon Jul 12 10:02:58 2004 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id i6CH0hOP006956 for <[[email protected]]>; Mon, 12 Jul 2004 10:00:44 -0700 (PDT) Received: from imo-m19.mx.aol.com (imo-m19.mx.aol.com [64.12.137.11]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id i6CGxgMR006904 for <[[email protected]]>; Mon, 12 Jul 2004 09:59:42 -0700 (PDT) Received: from [[email protected]] by imo-m19.mx.aol.com (mail_out_v37_r2.6.) id t.1a3.26a75161 (4262) for <[[email protected]]>; Mon, 12 Jul 2004 12:59:39 -0400 (EDT) From: [[email protected]] Message-ID: <[[email protected]]> Date: Mon, 12 Jul 2004 12:59:39 EDT To: [[email protected]] MIME-Version: 1.0 X-Mailer: 9.0 for Windows sub 5031 Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.5b1 Subject: [SBB] Nictitating Membranes X-BeenThere: [[email protected]] X-Mailman-Version: 2.1.5b1 Precedence: list List-Id: South Bay Birding List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Errors-To: south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by plaidworks.com id i6CH0hOP006956 All: On Saturday’s field trip to Charleston Slough we had a preening Common Moorhen which some of us were looking at to see its short, red, “bicyclist’s shorts” , when somebody spotted the white Nictitating Membrane which briefly showed up when the bird was preening deep under its wings. Pat Kenny reports that, "My American Heritage Dictionary said a nictitating membrane (aka nictating membrane) was found in birds, reptiles, and some mammals to help keep the eye clean." This has inspired me to tell what little I know about the nictitans in birds: On page 80 of Welty’s, “The Life of Birds,” he implies that perhaps all birds have a nictitans. In examples he briefly mentions that, “… in diving ducks, loons, and auks [the nictitans] has in its center a clear lens-shaped window of high refractive index that serves the bird under water as a ‘contact lens’ . Unlike other birds, owls have opaque nictitating membranes. The Magpie uses its nictitans in an unusual way: the white membrane has a conspicuous orange spot that the bird displays only during hostile or courtship encounters … [I have observed the same thing on Greater Roadrunners.] … The inner surface of the nictitating membrane is covered with epithelial cells which possess brush-like processes, so that the cornea is brushed with tears at every flick of this thin, transparent lid. … in most species the lids are used to close the eyes only in sleep, while the nictitans is reserved for blinking.” Perhaps the most interesting sight we had was of a Peregrine Falcon wildly chasing (and be chased by) Forster’s Terns. Eventually he timed it just right and captured a FOTE just after it dived into the water. Pat reported 53 species for the day. Frank Vanslager _______________________________________________ Do not post admin requests to the list. They will be ignored. south-bay-birds mailing list ([[email protected]]) Help/Unsubscribe/Update your Subscription: http://www.plaidworks.com/mailman/options/south-bay-birds/south-bay-birds-archive%40plaidworks.com This email sent to [[email protected]]