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Re: Web hints at more winter irruptors on the way...



Greetings, all--

We at the Cornell Lab and Audubon will be tracking this year's anticipated
irruption, at the BirdSource web site. When you see any of winter finches
and other irruptive species (including Red-breasted Nuthatches), we hope
you will enter them into the BirdSource database at
http://www.birdsource.org  (it's not quite up and running yet, I'll let you
know when it is, so please hold on to your records until then!)

BirdSource tracked the 1997-98 superflight invasion, thanks to birders like
all of you. You're invited to view those results -- where the irruptions
were strongest, what the different species were feeding on, etc -- at the
web site right now. (Go under "BirdSource Projects" and click on "Winter
Finch Survey") It will be interesting to see how this year's irruption
compares to that superflight.

As always, thanks for your interest and support!

Allison Wells
Cornell Lab of Ornithology and BirdSource
Ithaca, NY  14850
http://birds.cornell.edu
http://birdsource.cornell.edu

At 01:26 PM 10/18/99 -0400, you wrote:
>On Mon, 18 Oct 1999 PJPHILIP@aol.com wrote:
>> 
>> JR - Irruptions r fascinating ... anybody speculating on the 
>> whywithall of such events ??? R they all good indications ?? [these 
>> kinds of questions are easy to ask; I admit] - Phil J [NHAS]. > 
>
>Irruptions, as I understand them, are connected to seed and cone crops of 
>boreal plants, to boreal snow cover, and to rodent population 
>fluctuations. The irruptions of seed-eating birds are connected mainly to 
>the seeds and cones; the early and abundant appearance of Red-breasted 
>Nuthatches and Pine Siskins indicates that the seed and cone crop must be 
>poor this year. Crossbills, Evening and Pine Grosbeaks, and Redpolls 
>generally irrupt in the same years as Siskins, so be on the lookout for 
>these species.
>
>Raptors are tied to rodent populations and snow cover. Rodent populations 
>in the arctic - mainly lemmings and voles - naturally go through boom and 
>bust cycles. On top of this, snow cover varies from year to year; if the 
>snows are deep up north, then even in a boom year for rodents the hawks 
>and owls will have trouble locating food. I was at Whitefish Point, 
>Michigan during a year of very deep snows; there was a major owl 
>irruption that year, and many instances of starvation among owls later in 
>the winter. The big Saw-whet movement and early southern Rough-legged Hawk 
>sightings indicate that a raptor irruption may also happen this year. I 
>think the two co-occurring is most likely a coincidence; there have been 
>past years of finch irruptions without raptors and vice versa.
>
>Good birding,
>
>Josh
>
>
>
>Joshua S. Rose
>Duke University
>Department of Zoology
>
>jsr6@acpub.duke.edu
>http://www.duke.edu/~jsr6/
>
>
>