Date: Thu, 11 Dec 2003 00:28:56 -0500 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Brian Cassell Subject: Ecosystem Ranges & Hummer Species Adaptations MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I took ecology classes about 1 million years ago but the hummer discussions are dredging up old memories. I seem to remember that population numbers are governed by carrying capacity (food, etc) in the center/main part of a population's range. At the fringes of a population's range, geographic & climactic factors are often the governing factor. These factors will occasionally exceed the ability of the species to thrive. To me, this means that the hypothetical increasing population of over-wintering hummmers (d.t. genetics, feeders, weather or a combination of these things) could be instantly reset back to zero at any time by "normal" severe climactic events. Our short term perspective and relatively scanty data gathering lends itself to over/mis-interpretation. This isn't to say that we shouldn't gather data or try to interpret it. It's all good to see the beauty of life encapsulated in such a complex package and how it gets us all thinking. If this is off-topic, I apologize. As ever, Brian ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================