Thanks David, I’ll read up on the Mauritius Kestrel, sounds very interesting.
The genetic explanation certainly sounds feasible given how few birds there are
left now.
Some NZ friends also pointed out to me that gender bias can have a purely
ecological cause - e.g. Kaka which apparently have a male skewed ratio in many
areas because females are much more exposed to predation at nests. In that case
the bias is "the cause" of the population crash rather than a symptom of it,
which is why I wondered how long the gender bias has been apparent in OBPs...
Glenn
________________________________
From: David James <>
To: Debbie Lustig <>; birding-aus
<>; Glenn Ehmke <>
Sent: Thursday, 22 September 2011 5:27 PM
Subject: Re: [Birding-Aus] OBP article
Extreme gender bias appears to be a frequent symptom of inbreeding depression
when inbreeding becomes acute due to a large population crashing rapidly to a
small population. Such a sudden bottleneck can lead to a high percentage of
deleterious recessive genes normally not expressed suddenly becoming homozygous
and being expressed. Gender bias toward males almost claimed the last of the
Mauritius Kestrel some years ago, though determined intervention by Carl Jones
saved the thing. I'm sure there are mosre cases in birds. A few in mammals too.
David James,
Sydney
==============================
--- On Thu, 22/9/11, Glenn Ehmke <> wrote:
>From: Glenn Ehmke <>
>Subject: Re: [Birding-Aus] OBP article
>To: "Debbie Lustig" <>, "birding-aus"
><>
>Received: Thursday, 22 September, 2011, 4:03 PM
>
>
>Good article Debbie.
>As you point out the 100% breeding participation government agencies have been
>so keen to publicise this year is tempered by the fact only 8 pairs bred. Of
>course that obviously means there were only 8 females in the wild last year,
>and a bit of simple maths tells you that (assuming there are actually 35 birds
>left) there is a 400% male gender bias!
>I’m not sure I’ve ever heard of such a bias in any wild bird population,
>certainly not one that’s manifested “overnight”!… anyone?
>You are lucky indeed to have seen OBPs in the wild this year.
>
>________________________________
>From: Debbie Lustig <>
>To: birding-aus <>
>Sent: Tuesday, 20 September 2011 5:53 PM
>Subject: [Birding-Aus] OBP article
>
>
>Article written, immodestly enough, by me.Feedback?
>http://blogs.crikey.com.au/rooted/2011/09/19/on-the-hunt-for-the-mysterious-orange-bellied-parrot-australias-most-endangered-bird/
>
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