I don't have the reference at had but the number of extinctions on islands is huge.? For example, more species in Hawaii were extirpated prior to Cook's arrival than after.? Lots of "sub-fossil" species discovered.? This is in Storrs and Olson and Olson and Storrs .? It only deals with Hawaiian species but the case is the same for other islands.



Hal Michael

Olympia WA

ucd880 at comcast.net




----- Original Message -----
From: "Clarke F O'Reilly " < cfor at u. washington . edu >
To: "Robert Cleland " < cleland at u. washington . edu >
Cc: "Tweeters" <tweeters at u. washington . edu >
Sent: Thursday, December 9, 2010 3:19:28 PM
Subject: Re: [Tweeters] Re: bird extinctions

Would he have been using: 1 extinction/year over ~1,000 years from:

One per year
Presently there are 10,000 known bird species ? most identified after 1850 ? and an estimated 130 of those have become extinct since 1500, setting the extinction rate at roughly one species every four years.

But according to Stuart Pimm of Duke University, this rate fails to take into account three key factors: The continual identification of extinct bird species from fossil remains; numerous " missing" species that scientists are reluctant to declare extinct; and the fact that current extinction rates were not calculated using the proper baseline date for when the species was first described.

Taking these factors into account, the extinction rate is closer to one bird species per year, says Pimm , lead author of the study. And the rate could be triple that if not for recent bird conservation efforts.

"These are the best estimates of how fast we're driving species to extinction and will help us understand the extinction rates of other kinds of species," Pimm said. ?(from MSMBC report Bjorn Carey LiveScience Staff Writer, July 2006)

On Thu, 9 Dec 2010, Robert Cleland wrote:

> A biology colleague of mine said he had been told that since 1000 AD there
> have been nearly 1000 birds that have gone extinct. ?He didn't know the
> source of this figure. ?Does anyone out there have a reference to such a
> figure, or have strong feelings about whether it is correct? ?1000 seems high
> to me.
>
> ????????????????************************
> ? Robert Cleland
>
> ? Professor (Emeritus), Biology Dept. Box 355325
> ? Univ. of Washington
> ? Seattle, WA 98195-5325
> ? Phone (206) 543-6105; ?FAX (206) 685-1728
>
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