From south-bay-birds-bounces+south-bay-birds-archive=[[email protected]] Wed Jun 4 15:32:24 2003 Received: from www.plaidworks.com (localhost [127.0.0.1]) by plaidworks.com (8.12.9/8.12.9) with ESMTP id h54MTEa8021115 for <[[email protected]]>; Wed, 4 Jun 2003 15:29:15 -0700 (PDT) Received: from borg.inreach.com (mail.northcoast.com [209.142.2.71]) by plaidworks.com (8.12.9/8.12.9) with SMTP id h54MSUfF021072 for <[[email protected]]>; Wed, 4 Jun 2003 15:28:30 -0700 (PDT) Received: (qmail 14766 invoked by uid 507); 4 Jun 2003 22:28:26 -0000 Received: from unknown (HELO ?209.209.18.38?) (209.209.18.38) by borg.inreach.com with SMTP; 4 Jun 2003 22:28:26 -0000 Mime-Version: 1.0 X-Sender: [[email protected]] Message-Id: In-Reply-To: <001201c32ac5$e8bb0380$[[email protected]]> References: <001201c32ac5$e8bb0380$[[email protected]]> Date: Wed, 4 Jun 2003 15:26:41 -0700 To: "Garth Harwood" <[[email protected]]>, "SBB" <[[email protected]]> From: Ruth Troetschler <[[email protected]]> Subject: Re: [SBB] Nestboxes, uncommon birds, and an Acorn Woodpecker mystery Content-Type: text/plain; charset="us-ascii" ; format="flowed" X-Content-Filtered-By: Mailman/MimeDel 2.1.2+ Cc: X-BeenThere: [[email protected]] X-Mailman-Version: 2.1.2+ 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]] Hi Garth-- I have never read about ACWO trying to nest in artificial cavities, but they have a pattern of eating their own eggs, eg. Koenig, W.D., Mumme, R. L.1997 The Great Egg Demolition Derby Nat. Hist. 106(5): 32-37. Describes the behavior & evolution of egg destruction by cobreeding female Acorn Woodpeckers. Mumme, R. L., Koenig, W. D.. & Pitelka, F.A. 1983 Reproductive competition in the communal Acorn Woodpecker, sisters destroy each other's eggs. Nature 306: 583-584. Removal stops after egg laying of remover begins. Sisters alternate in reproductive readiness from year to year. Mumme, R. L., Koenig, W. D. & Pitelka, F.A. 1983 Reproductive competition in the communal Acorn Woodpecker, sisters destroy each other's eggs. Nature 306: 583-584. Removal stops after egg laying of remover begins. Sisters alternate in reproductive readiness from year to year. Stacy and Koenig in their book on cooperative breeding birds, again describe these behaviors, and even infanticide by ACWO when a new breeder joins a group where the adult breeder has died. Since this is the pattern, if the ACWO in that area of your territory are short of nest holes, any hole they find with eggs may be seen as a competitor, and the eggs destroyed so the breeder has a chance to lay eggs. These authors state that the ability of Acorn Woodpeckers to survive depends primarily on the availability of the acorn stores. When these stores are lost the woodpeckers abandon the territory and probably die. If the same area is recolonized later, usually different woodpeckers appear. Because ACWO seem to be so common, most of us take them for granted, but I have observed many lost territories in the last 25 years as urbanization has expanded. Ruth Troetschler At 11:19 AM -0700 6/4/03, Garth Harwood wrote: > >For the first time ever, I had an ACORN WOODPECKER initiate nesting >in one of my boxes, along the eastern border of Arastradero >overlooking Hwy 280. I say "initiate", because an ACWO was sitting >on 3 large white eggs on 5/24, but when I checked on 6/2 there was >no sign of bird or eggs (there never was any nest material, just an >excavated indentation in the wood floor). If, as I suspect, the bird >simply carried her eggs to a different location where no large >bipeds seem likely to intrude, it would explain a lot of things from >that area over the years. Specifically, over the past several years, >all or portions of nests and eggs of ATFL, WEBL, HOWR, and VGSW >have disappeared from that corner of the preserve. During all of >that time, there has been persistent evidence of woodpecker interest >in the boxes there, but I had never made the connection before. This >week the evidence of possible ACWO nest predation is especially >compelling because of the removal of their own eggs AND the loss of >a complete swallow nest (again, nest and all) two boxes over which >had contained at least 2 eggs. And sure enough, the entry to the >latter box has been enlarged and the floor excavated. > >Anyone know of research into interspecific nest predation by Acorn >Woodpeckers? I have heard of woodpeckers interrupting each other's >efforts, but not this kind of generalized activity. (Incidentally, I >rule out other more common predators because I have "seen it all" >out there by now - each has its telltale signs. Human intervention >seems very unlikely given the obscurity of these off-trail locations >and inaccessibility; some are mounted as much as 16' high.) > >--Garth Harwood > > > >_______________________________________________ >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/rebugging%40batnet.com > >This email sent to [[email protected]] _______________________________________________ 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]]